< h1 class="pgc-h-arrow-right" > (i) overview</h1>
(1) Precious food. Bullfrog meat is white and tender, delicious and nutritious. Compared with chicken, duck, pig, cattle, sheep and other meats, bullfrog meat has a higher protein content, lower fat content and low cholesterol content. It also contains calcium, phosphorus, iron, thiamine, niacin, glucose, liver sugar and other nutrients. Therefore, bullfrog meat is a treasure that people like to eat, and it is also a valuable food at the state banquet.
(2) Advanced medicinal diet. Modern Chinese medicine believes that regular consumption of bullfrogs can supplement the qi, aphrodisiac water, activate blood accumulation, clear heat and disinfection, and make up for weakness and cough. Bullfrogs contain medicinal ingredients similar to lake frogs.
(3) Fine leather. Bullfrog skin is thin and tough, soft, elastic and colorful pattern, after scraping, washing, drying, trimming, dyeing, anti-corrosion and other processing, can make the best wallets, gloves, elastic ties, leather shoes and other leather products. At present, it is widely sold in southeast Asian and other countries, and a pair of bullfrog leather shoes is priced at up to 400 yuan. There is an increasing demand for trendy products made from bullfrog skin. The leather glue extracted from bullfrog skin is a high-quality viscose for jewelry, diamonds and other ornaments, and its dosage is also increasing. According to reports, about 1/2 of the bullfrog skins in Thailand, the Philippines and Singapore are currently imported.
(4) High-quality feed. Bullfrogs' internal organs account for about 12% to 24% of their body weight, and their heads and limbs and webs account for about 10%. The above by-products can be used as animal protein feed after being dried and pulverized (or directly utilized). From its nutritional composition and content, it is a high-quality feed for livestock, poultry and fish. According to the test: feeding layer chickens with bullfrog by-products (150 grams of fresh offal per day), the egg production rate increased significantly, with an average egg weight of more than 60 grams, and after 3 days of stopping feeding, the egg laying rate and egg weight decreased significantly. Bullfrog offal is added to pig feed, and for every additional 1 kg of bullfrog fresh offal fed over a period of 100 days, the pig's weight can increase by an average of 0.9 kg. Bullfrog offal is fed to sables, otters, fish and other animals, all of which achieve satisfactory results. Dried bullfrog powder made from bullfrog by-products can be used in place of fishmeal.
(5) Insect catching experts. Bullfrogs are large amphibian carnivores that are good at swimming, lurking, jumping on land (can jump up to 1.5 meters high), and have a strong ability to hunt pests. An adult bullfrog can prey on more than 10,000 insects a year, and each tadpole can eat more than 100 mosquito larvae per day. Most of the insects eaten by bullfrogs are agricultural and health pests, such as large borers, dilated borers, three-way borers, rice longitudinal leaf borers, rice bracts, rice leafhoppers, rice leafhoppers, rice tsubaki elephants, armyworms, grasshoppers, grasshoppers, inchworms, scarab beetles, weevils, kowtows, celestial bulls, yellow melons, termites, flies, maggots, mosquitoes, etc., which are the great nemesis of pests. Also eat small amounts of earthworms, spiders, snails, mussels, dragonfly larvae.
(6) Other uses.
1) Although the bullfrog contains less fat, the 1 pair of fat bodies at the front of the reproductive glands is rich in fat, and the refined bullfrog oil is a high-quality lubricating oil for precision instruments on aircraft and rockets.
Bullfrogs have developed endocrine glands, including pituitary gland, pineal gland, thyroid gland, parathyroid gland, thymus, adrenal gland, islet gland, gonads, etc., which can secrete different hormones. The pituitary gland alone secretes 10 hormones. Hormones extracted from endocrine glands are of great use in medicine and production. For example, a normal saline (concentration of 0.7%) suspension of the pituitary gland of bullfrogs, injected subcutaneously or finned into sexually mature fish and frogs at appropriate doses, can promote spawning of fish and frogs.
2) Bullfrogs are easy to breed artificially due to their large size, making it an ideal experimental material for teaching and scientific research. It has been carried on spaceships to experiment with space travel diseases, and it is widely used by hospitals for pregnant women tests.
In summary, bullfrogs can be described as treasures all over the body. With the development of science and technology, the role of bullfrogs will certainly be more, and the level of comprehensive utilization and deep processing will gradually increase, so the economic value of bullfrogs will inevitably multiply.
< h1 class="pgc-h-arrow-right" >(2) Biological characteristics</h1>
The bullfrog, whose scientific name is Rana catasbeiana shaw, is taxonomically a genus of chordates, vertebrate subphylums, amphibians, tailless orders, frogs, and frogs.
1． The external morphology of the bullfrog
The adult bullfrog is divided into three parts: head, trunk and limbs. No neck and tail. The skin of the whole body is bare, smooth and moist, with mucus.
(1) Head. The head is broad and flattened, slightly triangular, with a pointed front end, little resistance when swimming, and gray-green cheeks. The head is inhabited by organs such as the mouth, nose, eyes, eardrum, and vocal sacs.
Eyes: 1 pair of large eyes with oval extrusions above both sides of the head. Have an inactive upper eyelid and an movable lower eyelid. There is a transparent film that covers the eyeball when diving, which has a protective effect. At night, the pupils dilate and occupy almost the entire surface of the eye. At this time, if you irradiate it with a flashlight, it will show a crystal light blue or light green. Bullfrogs tend to stay still in direct light, and can be caught at night with this feature. Bullfrogs have a wide field of vision, and only objects directly behind and above the frog's body are difficult to perceive, and objects within 10 meters or within 2 centimeters are invisible.
Tympanic membrane: A rounded tympanic membrane behind each eye, located on the orifice line. It is in the same plane as the skin and has no external auditory canal. It conducts sound waves and produces hearing, and bullfrogs have large eardrums and are sensitive to hearing.
Vocal sacs: Male frogs have yellow throats (females are white) with vocal sacs inside, and the sound becomes loud under the action of this resonator, such as a cow barking. Female frog silent sac structure. When male frogs chirp during the reproductive season, the swelling and contraction of the vocal sacs is easily observed.
(2) Torso cadres. After the eardrum and before the cloaca hole is the trunk. It is the largest part of the frog's body, short and broad, and its abdomen is relatively large. The inside of the trunk houses most of the frog's internal organs.
(3) Limbs. The trunk is born on all fours, the forelimbs are shorter, and the adult male bullfrog has a developed marriage tumor on the inside of the thumb (Figure 1). The reproductive season is used to keep the female frogs. The thumb is hidden in the skin, so only 4 fingers are seen on the outside, that is, the second to fifth fingers, there is no webbing between the fingers, and there are no claws at the ends of the fingers. When bullfrogs inhabit land, they often stand upright on their forelimbs and support the front to facilitate the use of looking up and detecting the surrounding dynamics. When the frog falls, the forelimbs land first, so that the torso and head are protected from vibration damage. When bullfrogs inhabit the water, they often grasp the aquatic weeds on the surface of the water with their forelimbs, so that their heads are exposed to the water for a long time.
Fig. 1 Forelimbs of male and female bullfrogs during the reproductive season
1． Male 2. female
Bullfrogs have unusually thick and enlarged hind limbs. 5 toes, with frog webbing between the toes, and directly to the end of the toes. The hind limbs are the main organs of bullfrogs to jump and swim.
2． The functionality of each system
Bullfrogs have skin, respiratory system, skeletal system, muscle system, digestive system, circulatory system, excretory system, nervous system and sensory organs, endocrine system, reproductive system. The following describes only the structure and function of the skin, respiratory and reproductive systems most closely related to farming.
(1) Skin and respiratory system. Bullfrogs are amphibians with a ratio of 3:2 between the surface area of the skin and the surface area of the lungs, and the skin and lungs are important respiratory organs. During bullfrog hibernation, it breathes almost entirely on the skin. Tadpoles have no lungs, have gills, and breathe by the skin and gills.
Skin: Bullfrog's skin consists of a thin epidermal layer and a thicker dermis layer. The epidermis is composed of stratum corneum and germination layer, and 1 to 2 layers of cells in the stratum corneum begin to keratinize, but the degree of keratinization is not deep, there are still living cells, this slight keratinization, to a certain extent, can prevent water evaporation. Completely keratinized cells often fall off in pieces, often floating on the surface of the water of the breeding pond, the lowest hairline cells of the epidermal layer have a strong ability to grow, the newborn cells can gradually replenish the stratum corneal cells that have fallen off, and there are many glands distributed in the dermis layer, which can secrete mucus, drain out of the body, keep the skin moist, and have rich nerve endings and blood vessels. Moist and capillary-rich skin is conducive to absorbing oxygen from the air and expelling carbon dioxide (Figure 2).
Fig. 2 Skin of bullfrogs
1． Epidermal layer 2. Dermis Layer 3. Mucus glands 4. Granular glands 5. blood vessels
The above characteristics of bullfrog skin make it have the function of protecting the body, keeping it moist, preventing excessive evaporation of water, and breathing, which is conducive to amphibian life from aquatic to terrestrial.
Respiratory system: Bullfrogs breathe directly in the air. Its pulmonary respiratory system is composed of organs such as the nose, oropharyngeal cavity, laryngeal tracheal chamber, and lungs. 1 pair of lungs, a thin-walled blind sac with a simple structure. The inner wall of the blind sac is honeycomb-shaped, which increases the area in contact with air, and the sac wall is covered with capillaries for gas exchange.
Bullfrogs breathe in the lungs in a pharyngeal way (Figure 3). In addition, oropharyngeal breathing can be performed.
Fig. 3 Aspirate state of the bullfrog during breathing [indicating that the breath enters the nose, pharynx (A) lungs (B)]
1． Esophagus 2. Nasal cavity 3. External nostrils 4. Inner nostrils 5. Tongue 6. Laryngeal gate 7. lungs
Tadpoles have gills. In the early days, there were 3 pairs of pinnate outer gills, and when the outer gills atrophied and disappeared, the inner gills gradually appeared, and the gill cavity communicated with the outside of the body with a water outlet hole. Both the outer gills and the inner gills have a large number of capillaries, and there is a large surface area in contact with water to facilitate breathing in the water, and the tadpole becomes a young frog that breathes with lungs after the inner gills disappear.
(2) Reproductive system. Bullfrogs are hermaphrodites whose reproductive system consists of both reproductive glands and reproductive ducts (Figure 4).
Fig. 4 The genitourinary system of the female bullfrog
1． Tubal peritoneal opening 2. Anterior fallopian tube segment 3. Renal fine tubes 4. Middle fallopian tube 5. Ureters 6. Uterus 7. Ureteral opening 8. Opening of the uterus in the cloaca 9. Cloaca 10. Bladder mouth 11. Bladder 12. Kidney 13. Adrenal glands 14. Ovaries 15. Fatty body
The reproductive system of female frogs consists of ovaries, fallopian tubes, uterus, cloaca, cloaca, cloaca, etc. The ovaries are a pair of multi-lobed, long-saced female reproductive glands located on the ventral surface at the front of the kidneys, and their shape and size vary from season to season. It is centered on a cavity with a small chamber filled with liquid. The outer wall of the ovaries has many egg cells outward. When the female frog grows for 1 to 2 years to reach sexual maturity, the frog in the hibernation and reproductive season, the egg cells are mostly mature, the ovaries are significantly enlarged, and filled with black round eggs, almost occupying most of the body cavity. In other periods, the ovaries are pale yellow and mixed with black particles. When the egg cells mature in the ovaries, they break through the outer wall of the ovaries and fall into the body cavity. After the mature egg cells fall into the body cavity, under the action of the contraction of the abdominal muscles and the flared cilia, they enter the flared mouth and then descend along the fallopian tubes. Because the fallopian tubes are rich in glands, the glial it secretes wraps around the egg cells that descend the fallopian tubes and is temporarily stored after reaching the uterus. The female frog is stimulated by the male frog holding, then a large number of eggs are released, and if the male frog is not hugged, it will ovulate sporadically, thus delaying the spawning date.
The reproductive system of male frogs consists of testicles, vas deferens, cloaca, cloaca, cloaca bore, etc. (Figure 5). 1 pair of testicles, oval, light yellow, also called sperm nest. Located on the ventral surface of the kidneys. Male frogs reach sexual maturity within 1 year, and this frog often has mature sperm in its sperm nest.
Fig. 5 The genitourinary system of the male bullfrog
1． Renal fine tubes 2. Urinary duct opening 3. Bladder opening 4. Bladder 5. Urinary duct 6. Adrenal glands 7. Kidney 8. Vas deferens 9. Testicles 10. Fatty body
Sexually mature male and female bullfrogs, in an environment suitable for reproduction, hold pairs, lay eggs, and fertilize. At a water temperature of about 26 ° C, the fertilized eggs hatched tadpoles after about 2 days and nights, the tadpoles began to actively feed after 3 to 4 days of static attachment, the growth and development of about 1 month began to appear hind limb buds, about 2 months of forelimbs appeared, by the 76th day the limbs were fully grown, the tail atrophy, disappeared, thus metamorphosing into a young frog, from the tadpole stage of aquatic life to amphibian life (Figure 6).
Figure 6 Development and metamorphosis of bullfrogs
1． Expanded eggs with glial membrane 2, 3. Tadpoles incubating 4. Tadpoles with external gills 5. Tadpoles with inner gills 6. Tadpoles with hind limb buds 7, 8. Tadpoles with hind limbs 9. Tadpoles before metamorphosis 10, 11. Tadpoles in Metamorphosis 12. Metamorphosis completed froglets
3． Bullfrog life habits and ecology
The observation and understanding of the living habits of bullfrogs can provide ideal ecological conditions for artificial breeding of bullfrogs in order to obtain the best breeding results.
(1) Life habits.
1) Amphibianism. Bullfrogs love water and also like to land. It inhabits unpolluted fresh water such as rivers, ponds, streams, shoals, lakes and other unpolluted rivers and grassy shores. Bullfrogs are amphibians that have only initially adapted to terrestrial life. Its skin is completely bare, its water retention performance is still poor, and it must be kept moist to carry out skin breathing and make up for the lack of simple lung structure. In addition, bullfrogs have no tailparts and must hold pairs, lay eggs, sperm, fertilize and hatch in water, and metamorphosis is also carried out in water.
2) Wildness. Bullfrogs have been farmed by humans for less than 100 years and are mostly wild-range types, so many of their wild traits are still maintained today. Such as strong alertness, fear of humans, slightly disturbed to jump, escape or diving, drilling mud, the use of protective colors lurking in the grass, bullfrog jumping up to 1.5 meters, jumping long up to 5 to 6 meters, climbing barbed wire fences up to 1 meter high, you can also drill out of a small hole out of the farm, often do not eat under people's watch, it is difficult to hold, spawn or sperm in a noisy environment.
3) Eating habits. Tadpoles are mainly plant-based foods, and adults are mainly animal foods. Adults have large eye distances, cannot form binocular vision, seem invisible to stationary objects, and are sensitive to moving objects, and are good at finding and preying on active animals. Rarely eat food in natural conditions. However, in the absence of food, hunger is unbearable and cannibalistic, generally for large frogs to eat small frogs, there may also be a healthy frog attacking the phenomenon of aging frogs, hungry bullfrogs also eat mixed with live bait or passive movement of dead things (such as artificially prepared feed), through domestication can change the habit of eating live food.
4) Gregariousness. Bullfrogs generally do not move in groups, but they often coexist in a few or a dozen, and in the absence of interference, these frogs have a roughly fixed habitat. Especially during the reproductive season, they often move to land and water places with excellent environments to sing wedding songs, and then reproduce. After completing reproductive tasks, each can return to its original habitat. This directional migration can be up to 9 km away. Someone blinded the bullfrog, and it can still return to its original habitat from 800 meters away. So it's no surprise that bullfrogs can return to their original habitat on rainy nights.
5) Cold-blooded warming. Bullfrogs are cold-blooded animals whose body temperature changes with ambient temperature and do not have the structural function of constant temperature regulation. Therefore, the growth and development, reproduction and various activities of bullfrogs are obviously restricted by seasonal, especially water temperature changes. For example, in the northern temperate zone, bullfrogs have the habit of hibernating for 4 months, in China's Liangguang, Taiwan, Hainan, Yunnan, only hibernation for 1 month, in the moderate temperature of artificial breeding conditions, bullfrogs do not hibernate.
(2) Main ecological factors. Bullfrogs' living habits, activities, growth, reproduction, population growth and distribution are closely related to the external environment. The main conditions affecting bullfrog farming include temperature, humidity, light, water quality (such as dissolved oxygen and pH, salinity, etc.), food, natural enemies, etc.
1) Temperature. When the water temperature is 9 to 12 ° C, the bullfrog stings out and the hibernation ends, which is the season of spring and warm flowers. The water temperature reaches 18 to 32 ° C or more, about May to August, bullfrogs begin to hold pairs, lay eggs, sperm, hatch, metamorphosis and other reproductive activities. The water temperature drops below 6 to 12 ° C, and the bullfrog enters the hibernation period, begins to burrow, and closes its eyes to hunger strike. At this time, the number of breaths is reduced, and even the lung breathing is stopped, and the oxygen consumption is reduced. The start and end time of hibernation is moved from south to north in China, one by one, and advanced. The appropriate temperature for bullfrog growth, development and reproduction is 20~32°C, and the optimal temperature is 25~30°C.
Bullfrogs are frozen to death at a critical low temperature of 0 to 0.05 °C, and if they are too long below 0 °C, they freeze to death. The order of the freezing process is four stages: the first stage, the subcutaneous cavity, lymph fluid freezing; the second stage, the limb muscles, body lumen and internal organs freeze, followed by the eyeballs, brain and spinal cord began to freeze; the third stage, the heart, blood vessels and the blood in them began to freeze; the fourth stage, when the brain and blood are completely frozen, as the body temperature drops to -1 ° C and deep freezing occurs. It is reported that when bullfrogs freeze victims reach the first three stages, there is still a possibility of resurrection. But if it progresses to the fourth stage, it is death. The water temperature is below 20 °C and bullfrogs do not lay eggs. Below 10 °C, sperm and eggs cannot form.
Bullfrogs have a lethal high temperature of 39 to 40 °C. In the heat, the bullfrog struggles, swims, and jumps sharply, after which the body loses its balance and dies soon after. Bullfrogs that die of heat cannot be resurrected. No eggs are laid at water temperatures above 35°C.
The optimal water temperature for tadpole growth and development is 25 to 30 °C. Tadpoles are more hardy and can overwinter safely in clean water under ice. Hibernation begins at 4 °C, hibernation ends at 5.8 °C, and feeding begins at 9 °C. It has poor tolerance to high temperatures, and when the water temperature reaches 35 ° C, it is restless and floating, and it is fatal at 40 ° C.
2) Humidity. Tadpoles are like fish, they can't live without water. Juvenile frogs and adult frogs mostly live in water or on the shore with high humidity. Young frogs can die by sun exposure in dry air for 30 minutes. Staying in dry air for 20 hours will also dry up. Adult frogs are slightly more tolerant of drought than juvenile frogs, and can die quickly after more than 3 hours in dry air at 50 °C.
3) Illumination. Light has an impact on the caloric metabolism, behavior and life cycle of bullfrogs.
Seasonal changes in light affect the activity of the gonads. If bullfrogs are kept in dark conditions for a long time, the gonadal maturation is interrupted, or sexual activity is inhibited, so that egg laying and sperm are stopped.
4) Water quality. Water quality includes the amount of dissolved oxygen, pH, salinity and content of microorganisms and plankton.
Dissolved oxygen: Bullfrog adults can breathe in the lungs, in general, the amount of dissolved oxygen in water has little effect on it, but it has a great impact on egg hatching and the growth and development of larvae.
The dissolved oxygen volume of water is closely related to the water temperature, the amount of dissolved oxygen at high water temperature is small, and the amount of dissolved oxygen at low water temperature is more. For example, when the water temperature is 20 °C, 1 liter of water contains 9.7 cubic centimeters of oxygen, and at 30 °C, it is reduced to 5.4 cubic centimeters, and the excessive reproduction of algae or microorganisms in the summer pond often leads to hypoxia in the water, especially in the case of tadpole culture density, which will cause tadpole hypoxia death.
Adult bullfrogs breathe through their skin to obtain dissolved oxygen in water, but this is only an auxiliary way of breathing. During the active period of adult bullfrogs, oxygen is obtained directly from the air mainly by lung breathing. If the bullfrog is completely immersed in water, its life expectancy decreases sharply with the increase of water temperature. It can be seen that bullfrogs in the water that lacks oxygen in the summer, if they do not breathe air on the surface of the water, they will soon die.
PH: The water pH suitable for bullfrog life is 6 to 8. In general, water sources that are not seriously polluted can basically meet the above requirements.
Salinity: Water often contains hydrochloride, sulfate, carbonate and nitrate. Salinity affects bullfrogs primarily through the density and osmotic pressure of water. Bullfrogs cannot survive in salty and alkaline waters. Salinity has a greater effect on tadpoles and eggs incubating. Therefore, the water used to breed bullfrogs is generally not sprayed with pesticides and fertilizers. If it is necessary for disease prevention, some suitable drugs can be applied, and the water should be appropriately changed after the disease is eliminated. In general, rivers, lakes, ponds and streams that are not seriously polluted can meet the needs of bullfrogs in terms of salinity.
Microorganisms and plankton: If the water is fertile, the plankton and microorganisms multiply more, which not only provides bait for tadpoles, but also provides favorable conditions for the spread of pathogens. In this case, it is especially necessary to do a good job in the prevention and control of bullfrog diseases and insect pests, and appropriately control the reproduction rate and number of microorganisms and plankton. Especially in the summer high temperature season, there may be overgrowth of some harmful algae in the breeding pond, which will consume too much nutrients in the pond water, affect the activity of bullfrogs and tadpoles, and even be entangled in algae and cause death.
The control methods for these harmful algae are: manual removal, with 0.1 ‰ copper sulfate solute poured into the pool water, the dosage per cubic meter of water body 0.7 ~ 1.4 grams, algae will soon die on their own, after the algae is removed, the water should be changed immediately to avoid bullfrog poisoning.
There are many water sources for breeding bullfrogs, common ones are river and lake water, well water, groundwater, mountain spring stream water, tap water, alpine snow water and so on. Rivers and lakes, pond water is more fertile, organic matter and small organisms, we must pay attention to prevent water pollution and pest control. Well water, groundwater and alpine snow water temperature is low, tap water contains chlorine, should be exposed to sunlight for 3 to 4 days, and stored for 7 days, and then introduced into the breeding pond, or per ton of water with sodium thiosulfate 1 g after treatment. Rainwater falling over the city may absorb harmful pollutants in the air during the descent process, and should not be used as a separate hatching water for bullfrogs. Of course, unpolluted rainwater can be used directly to farm bullfrogs and tadpoles.
5) Food. Bullfrogs feed mainly on animals. The types of animals include link animals, arthropods, molluscs, fish, amphibians, reptiles and even young birds and mammals, of which arthropods are more insects. Bullfrogs also eat a small number of plants, mostly leaf fragments, flowers, and seeds (Table 1). During the gastric examination, it was found that after the digestion of animal foods, the plant foods swallowed remained intact, indicating that bullfrogs have a far better ability to digest animal foods than digest plant foods. Bullfrogs are gluttonous, eat large amounts, and are resistant to hunger. A 300-gram bullfrog, after preying on 4 grasshoppers, swallows a 20-gram frog, and the amount of food at a time is about 30 grams. When the bullfrog is fully eaten, its stomach can be more than 10 times larger than when it was hungry. Bullfrogs eat the most when the water temperature is 21 to 30 °C from July to September, and the amount of food is reduced when the climate becomes colder and the water temperature decreases. Full-fed bullfrogs can tolerate starvation for 4 to 12 months without dying. This is mainly due to the fact that the liver of the bullfrog can store a large amount of hepatic glycogen, the fat body can store fat, and the metabolism in the hungry state is greatly reduced. Bullfrog feeding is mostly carried out at night, in the natural state, more hidden, when the food is approaching, suddenly jump, with a long tongue rolled out to catch, swallow, and finally the forelimbs to clean the periphery of the mouth. Bullfrogs can also jump, swim, crawl to find or approach food, and launch surprise attacks. Artificially bred bullfrogs can be domesticated to a fixed bait table to swallow artificial bait.
Table 1 Types of food for frogs
Bullfrog tadpoles feed mainly on plant foods, such as green algae, cyanobacteria, diatoms and so on in algae. As they grow, they also eat grasshoppers, water fleas, rotifers, sycamores, and animal carcasses. When artificial rearing, tadpoles can be fed algae growing in fertilizer water for 3 to 4 days after hatching, egg yolk filtrate after 5 to 6 days, and mixed feed made of animal and plant raw materials (the mix ratio is 4:6) after 14 days, such as soy milk, soybean cake powder, wheat bran, rice bran, chopped animal offal or minced meat.
<h1 class = "pgc-h-arrow-right" > (iii) preparation before breeding</h1>
1． Investment readiness
(1) Intellectual investment. In order to do a good job in bullfrog breeding, before the start of production, it is necessary to understand the dynamics of bullfrog breeding, relevant biological knowledge, specific management and harvesting, processing technology, economic accounting, and information on supply and marketing. Only in this way can we ensure the success of breeding and obtain more ideal economic and social benefits.
The first preparation is to cultivate talents, arm their minds with scientific knowledge, and other problems can be solved, so that they can spend less money, do more things, do good things, and ensure the success of bullfrog breeding.
(2) Capital and material investment. Generally speaking, for people who already own land and waters, the investment in bullfrog farming mainly includes the following aspects: the construction of frog farms, breeding sources, bait and other expenses, including wages, water and electricity, medicines, transportation, land taxes, housing construction, tools and machinery and equipment, etc. Purchase and depreciation costs.
All of the above investments should be calculated, raised, and done according to their ability, and finally determine the scale and breeding method of bullfrog farming.
2． Principles for the selection of frog farms
Choosing the appropriate frog farm site is an important task before the establishment of the farm, and it should be carefully considered. Basic principles of site selection:
(1) Bullfrog life habit requirements. The living habits of bullfrogs, such as amphibians, wildness, temperature change and special diet, determine that bullfrog sites should be selected in places with land and water environments, quiet, warm, overgrown plants, phytoplankton and insects. Places with noisy sounds and serious vibrations should not be selected as frog farms, otherwise bullfrogs will not be able to grow, develop and reproduce normally.
(2) The actual needs of production. If the frog farm is a breeding farm, the site should be as close as possible to the vicinity of the frog farm that requires a large number of seed sources to reduce the cost of seed source transportation. If the frogs farmed are mainly for export, it is best to choose a port and station near which is convenient for foreign trade. For example, frog farming is mainly for domestic consumption, and most of the sites should choose the suburbs of large cities to improve economic benefits and reduce transportation costs.
(3) Terrain. The farm floor is best tilted slightly to the southeast, so that the direct sunlight is large, the light is strong, and the ground temperature and water temperature rise faster, which is beneficial to the growth and reproduction of bullfrogs and their baits. This kind of terrain, which can be affected by the southeast monsoon in summer, fluctuates the water surface and increases the oxygen content in the water, which is very beneficial to the growth of bullfrogs, especially tadpoles.
(4) Water source and water quality.
1) Water quality. China's freshwater waters are vast. Different water sources will determine the physicochemical properties of water, and have a significant impact on the temperature, salinity, oxygen content, pH, water color and fertility of water. Therefore, we must pay attention to the investigation of the type of water source and the water quality.
2) Changes in water level. It is necessary to investigate the changes in the water level in the water area within one year or even several years, so as to select sites that have water in times of drought and do not flood during waterlogging.
3) The degree of pollution of waters. To investigate whether the water source is polluted before it reaches the site, the focus of the investigation is whether the river water and groundwater are polluted by the city's sewer sewage and industrial sewage, and chemical analysis methods and biometric methods are commonly used in water pollution surveys.
(5) Soil. Different kinds of soils often differ in their composition, pH, salt types and quantities, oxygen content, permeability and fertility, which has an impact on the growth of aquatic organisms, the environment of frog ponds, and a greater relationship with tadpole rearing.
(6) Transportation. Large bullfrog farms, seed sources, products, feed transportation volume is larger, in order to ensure survival, save time and transportation costs, frog farms should be built in convenient transportation places.
(7) Electricity. In order to install black lights and other electrical equipment (e.g. pumps, beaters, pulverizers, pellet bait machines, puffed bait machines, dryers, telephones, daily lighting, etc.) to attract insects, farms should be established where electricity is available.
(8) Drainage and irrigation system. The water level of the breeding pond should be able to be controlled freely and easily drained and irrigated, so as to effectively control the water temperature, dissolved oxygen and pests and diseases, which is conducive to harvesting and overwintering. The water used in frog farms is likely to be related to the irrigation water source of farmland, and whether there is a contradiction between the two should be considered and prepared accordingly. In order to avoid unnecessary losses caused by the inability to balance the two during drought or drainage.
(9) Bait. Farms should be established in areas rich in bait so that they can attract a large number of insects and supply a large number of plankton, snails, loach, small trash fish and other bait, or have abundant and inexpensive raw materials and land for the production of bait in the area, such as nearby cattle farms, pig farms, chicken and duck farms that supply livestock and poultry manure, and food processing plants that sell scraps, etc., in order to cultivate plankton for breeding ponds, breed earthworms, maggots, yellow mealworms, etc.
(10) Living and production buildings. Sites should have or are suitable for bullfrog farmers to live and work in order to facilitate management.
3． Construction of bullfrog farms
According to the needs of production, the characteristics of ponds, and the living habits and ecological requirements of bullfrogs, careful consideration should be given to the construction of bullfrog breeding ponds.
(1) The construction of breeding ponds. Bullfrog breeding ponds are divided into tadpole ponds, juvenile frog ponds, adult frog ponds, spawning ponds and hatching ponds according to the reproductive period of the bullfrogs raised. Figure 7 shows the layout of a bullfrog farm in the Philippines, for reference only.
Figure 7 Layout of various types of breeding ponds in bullfrog farms
NP． Hatchery BP. Spawning pool TP. Tadpole culture pond RP. Juvenile or adult frog breeding ponds (unit: m)
According to the suitable breeding density of bullfrogs in each period, for self-propagating and self-rearing edible frog farms, the area ratio of the above-mentioned breeding ponds built in the farm is roughly 1:10:20:5:0.05. For breeding farms, the proportion of frog farms can be appropriately reduced. As for the size of the total area of the farm, it depends on the production needs and the possibility of human and financial resources. All kinds of frog pools should not be too large and too small. It is too large, the management is difficult, the feeding of bait is inconvenient, and once the disease and pest occur, it is difficult to isolate and control, often causing unnecessary losses. Too small will not only waste land, building materials, but also increase the number of operations, while too small water body, its physical, chemical, biological properties are unstable. The shape of the pool is generally rectangular, and the ratio of length to width is 2 to 3:1.
Tadpole pond: each pond is generally 6 meters × 2 to 3 meters is appropriate, the pool depth is 0.6 to 1 meter, the pool wall is a muddy or masonry cement structure, and the slope of the pool wall should be small (about 1:10), so that the tadpole can adsorb it to rest, and facilitate the landing of young frogs after tadpole metamorphosis. The pond wall is equipped with an inlet and outlet to facilitate drainage and irrigation (Figure 8). There is a bait table in the pool, and the plastic mesh surface of the bait is about 10 cm below the water surface. The pond is planted with some floating aquatic plants, such as water hyacinth, which creates good conditions for tadpoles to inhabit. A wall was built around the tadpole pond to prevent enemy intrusion.
Fig. 8 Tadpole culture ponds
1． Tadpole concentration 2. Thatch or planks 3. Water
Tadpole ponds of the same structure must be set up in several batches to accommodate tadpoles about 20 days after hatching, or for small tadpoles to be evacuated after they grow up to reduce the density of culture.
(2) Juvenile frog breeding ponds and adult frog breeding ponds. The form and structure of the two are similar. The area of each juvenile frog breeding pond should not be too large, and it should be flexibly determined according to the number of frogs raised and the management level. The embankment slope of the aquaculture pond is 1:25, the width of the embankment is 1 m, and the depth of the pond is 0.6 m. Depending on the development of the young frogs, adjust at any time and raise them at different levels, so as to avoid the big young frogs from eating the small frogs. Each adult frog breeding pond is preferably set up as a small island or floating island. Adult frog ponds should also be cultured according to the size of the frog. Both juvenile and adult frog breeding ponds must be equipped with drainage and irrigation pipes, and artificial caves should be dug around the pond or on small islands, and shade shelters can also be set up. In addition, a bait table must be set up at the surface of the water for the bait to be used. There should be a fence around the pond, and black lights should be installed on the water to lure flying insects. The structure of the juvenile and adult frog ponds is shown in Figures 9, 10 and 11.
Fig. 9 Bullfrog culture pond (profile view) 1 inch ≈ 2.45 cm
Fig. 10 The plane of the adult frog pond (left) and the juvenile frog pond (right) (unit: cm)
1 inch ≈ 3.3 cm
Fig. 11 Slice of the adult frog pond (top) and the juvenile frog pond (bottom) (unit: cm)
(3) Spawning pond. Its building specifications are the same as those of adult frog breeding ponds, but not too large, about 20 meters × 2 meters is appropriate, and the water depth is more suitable for 15 to 40 cm. Land accounts for about 1/3 of the total pool area. It is best to set up 2 to 3 spawning ponds for frogs at different spawning periods to use for spawning and spermatosis (Figure 12). The ecological environment of the spawning pond should be set up similar to natural conditions to facilitate reproduction.
Figure 12 Bullfrog spawning pond
(4) Hatchery. The area is 2 meters× 1 meter or 1 meter× 0.5 meters, built with masonry cement, or plastic boxes of the corresponding size can be used, the height of the pool wall is 0.6 meters, and the water depth is 0.15 to 0.4 meters. There should be an inlet and outlet, the bottom of the pond is covered with sand about 6 cm thick, there is a shelter, or some duckweed on the water surface. The number of hatchery ponds depends on the number of broodstock cultured frogs and the need to hatch in batches of eggs laid by different broods or at different times.
The layout of various breeding ponds in bullfrog farms should be designed reasonably to reduce transportation, save manpower and material resources, and meet actual needs.
4． Walled building
Bullfrogs are good at jumping, swimming, drilling, and climbing, so they must set up anti-escape walls, and it also plays a role in preventing the invasion of natural enemies. The walls are generally 1.5 meters high and buried 30 centimeters deep. Depending on the category of building materials, enclosures can be divided into the following categories:
(1) Bamboo wall. Thin bamboo pieces are erected between wooden or cement columns, and tied firmly with wire so that they are closely connected to each other. The bamboo wall is more than 1.5 meters high, the burial depth is 30 cm, and the inside of its top should be made of a bamboo eaves with a width of 10 cm, which is inclined inward. Bamboo walls are easy to take in the south, the price is low, but the degree of solidity is slightly worse, and it is necessary to check often for damaged holes, and gradually decay after 1 to 2 years and need to be rebuilt.
(2) Brick and wood walls. A densely connected board wall is made of 5 cm thick wooden planks, and the base of the board wall is made of brick, and deep into the soil to connect with the bricks paved at the bottom of the pool, and then the board wall is erected on the brick foundation, which is clamped with wooden columns, and the east, west and south sides of the brick and wood wall must open windows to facilitate air circulation. The window should be nailed with barbed wire or plastic window screens to prevent bullfrogs from escaping from the window. The inner side of the wall should be made of wooden eaves about 10 cm wide. This wall has a good effect and a low price, but the base of the wall is gradually decaying after 1 to 2 years.
(3) Brick walls. Ordinary brick walls are built with various bricks, generally the foundation is three or seven walls, and the above ground part is two or four walls, such as hollow bricks or large pressed bricks. The inner side of the wall should be made of brick eaves with a width of 10 cm, and windows and doors should also be set up. Brick walls are strong and durable, with good protective performance, but the cost and amount of work are large.
(4) Other types of enclosures. There are earthen walls, asbestos tiles, plastic film, plastic sheet, nylon fine mesh and so on.
5． Preparation of bait
Bullfrogs grow and reproduce quickly, under intensive breeding conditions, the number of individuals and weight can be greatly increased in the short term, and the consumption of bait is large, especially the bullfrog adults, mainly animal bait, so prepare sufficient bait (which must have a considerable amount of live bait), which is the key to ensuring the success of breeding bullfrogs. In a sense, the amount of animal-based bait determines the scale of bullfrog farming.
(1) Breeding of live bait. There are many live baits for bullfrogs, but at present, in the breeding and application of live baits, the more successful and easy to form a production scale are the culture of earthworms and mealworms. The following focuses on the methods of farming earthworms and introduces other methods of live bait culture for everyone to choose from. The collection of wild food is only suitable for the cultivation of a small number of bullfrogs, which only plays a small role in large-scale production and destroys the natural ecological balance, and is not introduced here.
1) Farming methods of earthworms. At present, the earthworms suitable for artificial culture are mainly the red child Aisheng earthworm (a red earthworm weighing about 0.4 grams). There are many breeding methods, and only two of them are briefly introduced below, which can be selected according to local conditions.
Basket culture method: This is the most common method of culture. The materials for making boxes and baskets can be made of wood, bamboo, wicker, thorns, rattan, plastic bags, etc., and the size is suitable for 1 to 2 people to move. The size of the culture tank is diverse, and its length, width and height are generally the following (measured in centimeters): 40×20×30, 40×35×30, 60×50×25, etc. The basket can be rectangular or round, and the size can be similar to the above box. The bottom and sides of the box should preferably have drainage holes or ventilation holes, the sides have handle handles, and the feed loading capacity should not exceed 20 cm deep, preferably about 15 cm. The amount of loading is too much, the ventilation is poor; the loading amount is too small, it is easy to dry, and the amount of earthworm feeding should be reduced. The surface of the feed should be covered with a layer of plastic film or wooden board. One can condense water, and the other can reduce the evaporation of water. The size of the box hole is suitable for diameter 0.7 to 1.5 cm. The hole area accounts for 15% to 40% of the box wall area, preferably 20% to 35%. In addition to draining and aeration, these holes can also make the box temperature not too high due to feed fermentation, and at the same time, the earthworm manure can be gradually dropped, which is conducive to the separation of earthworm manure, so it is best to lay a plastic sheet on the floor at the bottom of the box in order to often clean the fallen earthworm manure. When the production volume is large, the boxes can be stacked and three-dimensionally reared. This saves ground and makes the most of space, while also facilitating observation, ventilation and drainage. In order to prevent earthworms from escaping, it is best to light the breeding room at night. Each basket generally stocks 1,000 to 3,000 earthworms. In boxes of 60 cm × 50 cm × 20 cm, 2,000 earthworms were stocked per box at the beginning, and at the appropriate temperature (about 20 °C) and humidity (75% to 80%), after five months of breeding, it increased to 18,000. Leave a 5 cm gap between the upper and lower layers of the stacked basket and between the adjacent baskets on the side to facilitate ventilation. If you are breeding outdoors, you should pay attention to shade and cover to prevent rain, snow and insects, and the bottom box should be elevated to prevent predators from invading. Such layered breeding tanks do not have to be sprinkled with water within 1 month, and the feeding humidity is still maintained at about 75% to 80%. This breeding method, which saves ground and manpower, can be used for factory production. It is much more productive than flat-land aquaculture (table 2). One of the disadvantages is that the box is perishable after moisture, so in addition to advocating the use of plastic products, it is best to carry out antiseptic treatment that does not affect the growth and development of earthworms.
Table 2 Comparison of the effects of box culture with flat-land cultured earthworms
Garden, field flat land breeding method: This method is characterized by a large breeding area, you can use the nearest garden, field leaves, dead roots, weeds, farm fertilizers and other organic matter, make full use of the garden, the field for earthworms to inhabit the favorable conditions (if there is natural shade, microclimate conditions for earthworm reproduction is more suitable). Under such conditions, the earthworms grown and multiplied are thicker and stronger than those raised at indoor constant temperature, and can directly use earthworms to improve the soil and promote agricultural and forestry production, although this method is greatly affected by natural conditions, the yield per unit area is low, but the cost is low. Therefore, it is a breeding method that deserves to be vigorously promoted and developed.
First, the garden breeding method is generally to open a ditch between fruit trees or other trees after the beginning of spring, lay feed in the ditch, put earthworms (including natural inducement), cover the soil to fill in, and properly maintain the humidity of the feed in the ditch after that. The width of the ditch depends on the width of the forest and the amount of feed. The depth of the ditch depends on the level of the groundwater level, the dryness and wetness of the soil, and so on. For example, the cultivation of earthworms in the mulberry forest, the mulberry tree row spacing is generally 1.3 meters, in the center of the row spacing to dig a ditch 35 to 40 cm wide, 15 to 20 cm deep, fill in the feed, breed earthworms, the result per mu (1 mu equivalent to 666.7 square meters, the same below) mulberry field can breed 204,000 earthworms, mulberry leaf yield nearly 1 times. The cultivation of earthworms between grape rows can harvest 2000 kg of grapes per mu per year, and more than 500 kg of earthworms, and the effect is very good.
Second, the field culture method is mostly combined with the cultivation of crops, and at the same time the cultivation of earthworms. In general, farmland with perennial plants is more suitable than that of annuals, and crops with dense foliage and long shade, as well as farmland with good water and fertilizer conditions, are more effective. For example, in the perennial, large foliar index of polymer grass rows, open a wide, deep 15 to 20 cm trench, put in the feed and earthworm species, after the soil cover often maintain the feed, soil moisture at about 30% to 33%. Pay attention to interlaced harvesting of aggregated grass leaves, and plant tall crops (such as sunflowers, corn, etc.) on the edge of the field. In winter, the aggregate grass withers and grows green manure crops between the rows to facilitate shade. In good condition, plastic film can be covered with plastic film for insulation. In addition, earthworms can be cultivated in farmland where crops such as white potatoes, broad beans, cotton, cabbage, wheat, and corn are cultivated. The harvest of earthworms can be carried out when the crops are ploughed and prepared after harvest.
2) Cultivation of fly maggots. Adult flies grow and reproduce faster than earthworms, and the average female can lay about 1,000 eggs in her lifetime, and the life cycle (referring to the time from the hatching of eggs to maggots to the time when pupae feathers into adult flies and begin to lay eggs) is about 15 days. However, when extensive farming, poor control becomes flies, which hinders environmental hygiene. When caged, it costs much more than earthworms and is one of the important sources of bullfrog bait due to its fast reproduction and high nutritional value.
Extensive flat-ground breeding: Fermented chicken manure, pig manure or food factory scraps (such as lees, soy sauce residue, vinegar lees), slaughterhouse scraps, etc. are mixed and spread flat on the ground to lure natural flies to lay eggs on them. Generally, about 150 grams of maggots can be harvested per kilogram of material in 7 days. The key to adopting this method is to harvest maggots in time and feed them to bullfrogs in time, otherwise a large number of artificially produced flies will fly out of the frog farm, which will bring great harm to people. You can also put the material for cultivating maggots into the sieve, put the sieve on the container, or hang 30 cm above the water surface of the frog pond, and use the light avoidance and drilling of the maggots to drill out of the sieve and fall into the container or bait plate to become the live bait for bullfrogs.
Cage: make several fly cages with a length of 60 cm, a width and height of 40 cm, and are sealed with nylon window screens on all sides, and a round hole with a diameter of 20 cm is opened on one side of the cage, with a cloth cylinder with two empty ends, and one end is sewn on the edge of the hole for adding culture material. Each cage can raise about 10,000 flies.
The feed of the flies is milk powder and brown sugar. Every 10,000 seed flies are boiled in 5 grams of milk powder and 5 grams of sugar per day, boiled in the right amount of water, and put in a small plate after cold, in which a few short straws are placed for the seeds to lick and suck. A small, deep basin or bowl containing 70% water content of wheat bran or rice bran is placed in the cage for seed flies to lay eggs. At 24 to 33 °C, female flies can lay about 100 eggs each time, and the eggs are lumpy. Every day, the bran and bran with eggs are removed from the fly cage, and placed on the maggot feed (the ratio of chicken manure to pig manure is 1:2) to hatch, the thickness of the material is about 7 cm, the humidity is about 70%, the temperature is 18 ~ 33 ° C, after 3 to 32 hours, the larvae can hatch, and the larvae can be harvested after eating manure for 4 to 5 days. Every 500 grams of manure can raise about 10,000 maggots, with an average weight of 20 to 25 mg per piece, and the total weight is 200 to 250 grams, that is, the maggot ratio is about 2:1.
Once the seed fly lays eggs 5 to 6 times, it begins to age after 7 to 10 days, at which time the cage can be treated with boiling water to kill the aging seed fly, and then load the new breed fly.
3) Snail farming. There are many types of snails, and most of the currently farmed species are brown cloud agate snails. The main methods of cultivation are:
Wild farming: Choose leeward, dark, damp, weedy foothills, hillsides or wastelands as feeding grounds. Snails can also grow some snail-loving green plants such as musk, clover, nettle, sweet potato and vegetables. These plants can be used as feed for snails, but also as shade, increase the humidity of the environment, and are conducive to snail growth and reproduction. A wall was built around the snail farm to prevent the snails from escaping. The soil in the feedlot should be loose and moist to facilitate snail spawning and hatching. In this environment, about 250 snails can be raised per square meter. In the warm, humid and rainy south, wild snails are suitable for growth for a long period of time, sufficient feed and low cost, which is an effective method.
Box culture: with about 1 cm thick wooden board nailed into a feeding box, the size of the size according to the actual situation, generally conducive to operation management and saving of the board prevails. The box is covered with screens or bamboo curtains to prevent snails from escaping. In order to save land, the culture tanks can be stacked in layers, and their height should not exceed the height of a person. The bottom of the box is covered with wet sand or vegetable garden soil 3 to 5 cm thick. Place a wooden board on the sand as a feed table, on which fresh leaves of plants can be placed, and add some wet bran or rice bran and crushed eggshells or snail shells, pay attention to keeping the room moist. Clean the carton of leftover food and snail feces frequently and keep it clean so that the snails can grow and multiply well in the box. In order to facilitate management and harvesting, snails of different growth periods or different sizes can be cultured in bins. Generally, about 600 snails can be raised per square meter. This method is convenient and flexible, can make full use of indoor space, and can artificially control indoor temperature and humidity, which is longer than the growth period of wild aquaculture, and can obtain higher yields. However, it costs more manpower and material resources, and the production cost increases accordingly.
Greenhouse ground culture: in the greenhouse ground sand 13.3 ~ 20 cm thick, often kept wet, room temperature control at about 25 ° C, 33 cm from the ground installed a circle of low voltage (36 volts) anti-escape cable, snail touch the bare power cable by electric shock and retracted. Feeding and other management are similar to box culture. This method can be used to produce in large areas all year round.
Snails are plant-eating animals that do not consume meat and a lot of food, and have high economic value. Farmed snails are crushed and fed directly to bullfrogs, or the gastropods of snails can be taken for human consumption, and the scraps are used to feed bullfrogs.
The aquatic Fushou snail feeds on aquatic plants, grows and reproduces quickly, and has a thin shell, which is a good bait for bullfrogs and can be raised in bullfrog ponds or tadpole ponds.
4) Mealworm (also known as bread worm) cultured. Mealworm is originally a larvae of a food pest that has been selected and bred as artificially farmed animal food. It is a completely metamorphosed insect in the order Coleoptera, and its life history includes four periods: eggs, larvae, pupae, and adults (beetles). At room temperature of 25 °C and humidity of about 65%, the eggs hatch into larvae after 6 to 7 days. Under adequate supply of wheat bran, vegetable leaves or non-toxic leaves of leaves, the larvae molt 15 times. Every time it molts, the worm grows a little, grows and develops into a pupa after about two and a half months, and the pupa becomes an adult in about 1 week, and the adult worm is good at crawling, but cannot fly. Adults live for about 4 months, with the first 2 months being the peak of spawning. The newly laid eggs are pale yellow, oblong-oval, smaller than sesame seeds, and the surface of the eggs is often adhered to a small wheat bran, which is difficult to see with the naked eye. The life cycle of mealworms totals more than 3 months. About 2 kg of wheat bran can produce 0.5 kg of fresh yellow mealworm under general culture conditions. Each bite is about 60 cm long, 40 cm wide and 12 cm high, and the worm cage can raise 2 to 3 kg of large larvae. During the breeding process, attention should be paid to controlling room temperature and humidity. Sprinkle wheat bran and flat vegetable leaves (or non-toxic, palatable wild grass leaves and leaves) 1 to 2 times a day, and pay attention to the prevention and treatment of diseases and natural enemies.
5) Cultivation of grasshoppers. Grasshoppers are single-celled animals of the protozoa Phylum Ciliates , with an individual length of about 0.1 mm , living in water. On closer inspection with the naked eye, the grasshopper resembles a white chalk suspended in water, and when viewed with a microscope, it resembles an upside-down straw shoe. Grasshoppers are small but can be used as an excellent food for tadpoles.
Grasshoppers are generally cultured with straw immersion in water. Take fresh straw (old straw is also available), select a few sections near the root (here often adhere to the dormant bag of grasshoppers), cut it to 1.5 to 2 cm long, and then knead it loose and immerse it in the tank or pool water, the volume ratio of straw and water is about 1:5, and the amount of immersion is based on the water not overflowing the cylinder mouth. Then in the cylinder, the pool mouth covered with a clean plastic sheet to prevent debris and dust from falling in, in the water temperature of 20 ~ 24 ° C, bright environment, a few days later can see a large number of grasshoppers suspended in the water. From this point on, 1/4 of the straw soaking solution (containing grasshoppers) can be scooped up every day and poured into the tadpole pond as bait. Before scooping the straw infusion, you can also add water to continue soaking the straw, so that you can repeat the culture and use several times.
In natural ponds, gutters or puddles, a large number of grasshoppers or other single-celled animals can also be found to grow and multiply due to soaking in straw, wheat straw or other plants. It can also be used as a tadpole bait.
6) Cultivation of water fleas. Commonly known as fish worms and red worms, water fleas are ideal protein bait for small tadpoles. The cultivation method is to drain the water of the culture pond, after disinfection of the pond, sprinkle 1 kg of dried chicken manure and soy sauce residue per square meter of the pond (or add other livestock and poultry fertilizers), it is best to let the sun shine for 1 week and irrigate 40 cm deep, and put a small amount of water flea seed source. After a few days, the water turns green, and a large number of water fleas breed in the pool water in about two weeks. An appropriate amount of water fleas can be fished and fed to small tadpoles on a daily basis, and organic fertilizer can be applied to the pond water in an appropriate amount to facilitate the continued growth and reproduction of water fleas.
(2) The inducement of live bait. Taking advantage of the phototropism of insects, three black lights of 20 to 40 watts can be installed above the frog pond, arranged in upper, middle and lower rows. The upper light should be 1 to 2 meters above the wall to lure distant insects outside the pool. The light below is about 0.3 meters from the surface of the pool, so that insects can mistakenly fall into the water when they flutter the lamp, which is easy to be preyed upon by bullfrogs. The middle lamp acts as an inducement, attracting insects near the upper lamp to pass through the middle lamp to the lower light area. Each lamp is turned on for 6 hours a night, consumes about 0.2 kilowatts of electricity, and attracts insects from 1333.34 to 2000 square meters.
Every year from the valley rain to the frost season, 8-12 o'clock at night, turn on the lights to lure moths, planthoppers, leafhoppers and other insects, when there are more insects flying, you can turn off the lights from top to bottom, causing insects to fly faster and more into the pool. According to statistics, each 40-watt black light, from May to October, open for 6 hours a day, on average, each lamp can attract about 30 to 60 kg of insects per year. The insect attracts up to 0.5 to 1 kg per night.
In order to prevent black light leakage, rainproof devices should be installed, wires should not be exposed, stop turning on lights on rainy days, and often check the safe use of electricity and timely maintenance.
(3) Preparation of dead bait. In addition to breeding and inducing live bait, tadpoles and juvenile frogs and adult frogs must also be domesticated to eat artificially prepared dead bait. Only in this way can the supply of bait needed for a large number of bullfrogs be guaranteed.
1) Bullfrog dead bait preparation. It mainly includes the preparation of harvested green feed and processed bean feed, oil meal feed, bran feed, animal feed, inorganic salt feed, etc.
2) Preparation of artificial compound feed. The preparation of bullfrog artificially combined with bait should be based on the individual size, physiological state, feeding quantity and environment of bullfrogs and tadpoles, with reference to nutritional standards, nutrient composition and content of bait, and formulate a reasonable formula.
Bullfrog pellet feed recipe: 40% of soybean cake, 5% of vegetable cake, 10% of fish meal, 5% of blood meal, 30% of wheat bran, 10% of alfalfa powder. Stir and mix the above raw materials, then add the adhesive puffing, and then add the appropriate amount of cold water and stir into a ball. It is then processed into granular or puffed bait by a bait machine, dried (sun or dried) for preservation or direct feeding. The dry puffed bait should be hard but not hard, dense but not heavy, loose but not scattered. Such bait can float on the surface of the pond water for bullfrogs to feed for a long time, so as not to sink into the water and affect the water quality.
Tadpole powder feed recipe:
Recipe 1: 60% fishmeal, 30% rice bran, 10% bran.
Recipe 2: 50% of small trash fish, 25% of peanut cake, 2% of feed yeast powder, 10% of bran, 13% of wheat flour.
Recipe 3: 20% blood meal, 40% peanut cake, 12% wheat bran, 10% whole wheat flour, 15% bean cake, 2% inorganic salt, 1 vitamin additive.
Recipe 4: 20% meat powder, 10% cabbage leaves, 10% bean cake powder, 50% rice bran, 2% snail shell powder, 8% earthworm powder.
Formula 5: Silkworm pupae powder 30%, fish meal 20%, barley flour 50%, vitamins to taste.
Advantages of artificial compound feed: First, according to the different age and size of tadpoles, different specifications of feed suitable for their feeding can be made, and hobby substances can be added to improve the palatability and appetite of tadpoles. The second is to meet the requirements of tadpoles at different growth stages for protein and other nutrients. Third, an appropriate amount of agent can be mixed into the feed to prevent and control diseases and improve the survival rate of tadpoles. The above three points can significantly promote the growth and development of tadpoles. Fourth, it is convenient to feed, save labor and time, and is easy to store, which can be supplied all year round, getting rid of the influence of natural conditions. Fifth, the type retention is good, and the storage time in the water is longer, which reduces the pollution of water and the waste of feed, improves the utilization rate of feed, and thus reduces the production cost. For this reason, artificial compound feed has been widely used in bullfrog farming.
6． Selection of frog species
Before putting into production, it is necessary to carefully carry out the selection of seeds. Seed purchase and transportation of seed sources can be carried out in spring, summer and autumn, but from the perspective of temperature and transportation route and the time of experience, generally close-range, a small number of introductions, can be carried out in various seasons; a large number of introductions, long-distance transportation should be in spring and autumn, when the temperature is lower, transportation is safer.
(1) The choice of pro-frog. (1) It has the characteristics of bullfrog species. Be careful not to be confused with other frogs. (2) Pay attention to distinguish between male and female. The distinction between male and female is shown in Table 3, and the ratio of male to female should be 1:1. (3) Select 2 to 3 years old good-developed, physically robust adult bullfrogs. It is necessary to choose individuals with strong vitality, high egg laying, high sperm output, good quality, no injury, no disease, good jumping and swimming, lively temperament, inflated abdomen of female frogs, and a weight of about 300 (males) to 350 grams (females).
Table 3 Identification of male and female adult bullfrogs
Frogs should not be selected as frogs where the body and limbs have been stabbed, left with scars or holes, red limbs, bare phalanges, sluggish movements, dull skin, blackened or rotten.
(2) Tadpole and young frog selection. Pay attention to the typical morphological characteristics, body length and weight of different developmental periods, and require the selection of individuals who are physically strong, active, disease-free and trauma-free.
(3) Selection of bullfrog eggs. Look at the eggs with a microscope and select eggs that have been fertilized and whose embryos are developing before the 8-cell stage. For naked eye observation, eggs with no fungal overgrowth and black animals on the surface of the egg are selected.
Generally speaking, those who need to breed a large number of frog species by themselves should choose to buy frog species. In order to reduce costs, those who can breed profits in the same year should choose to buy young frogs or tadpoles, such as close distance and convenient transportation, and also choose to buy bullfrog eggs.
<h1 class = "pgc-h-arrow-right" > (iv) feeding management</h1>
1． Rearing management of tadpoles
The key to tadpole feeding is to not only cultivate the pond water, but also make the water quality not polluted and deteriorated, and the oxygen content is high. In every 100 tons of pond water every 1 to 2 weeks, 25 to 50 kg of livestock manure or non-toxic leafy grasses are pressed into the pond mud to make fertilizer, so that the pond water becomes grass green fertilizer water, and then oxygenation measures can be taken in the sweltering night to achieve the above purposes. On the basis of the fertilizer water, the appropriate artificial feeding, increase the animal protein bait, and increase the water temperature can accelerate the growth, development and metamorphosis of tadpoles.
(1) The basic requirements for baiting.
1) The bait must be fresh and clean. Forage should be disinfected with bleach powder (put 50 to 100 grams of bleach powder per ton of water and soak the hay in water for half an hour). Animal bait should be cleaned, and those that rot and deteriorate should not be fed, so as to avoid tadpoles from gastroenteritis and contaminating water bodies.
2) The bait should be diversified. Due to the different nutrients and their content of various baits, tadpoles have different preferences for different baits. Changing the bait frequently can increase the tadpole appetite, improve the utilization rate of bait, and obtain a more comprehensive nutrient. Tadpoles that eat a single bait for a long time not only have poor growth and development, but are also susceptible to disease.
3) The bait should be changed according to the external environmental conditions, tadpole reproductive period and health status. When there are thunderstorms, it is necessary to throw less or no bait, and the tadpole floating head is particularly serious in the morning, and even when there is a single tadpole death phenomenon, it is necessary to control the bait.
(2) Bait feeding method.
1) Bait table. Several bait tables are set up in the tadpole pond water, and their size and quantity are determined by factors such as the pond area and the density of culture. The artificial bait is mashed and soaked, and then placed on the bait table, which is conducive to observing and checking the amount of bait and facilitating the removal of residual bait.
2) Sprinkle the whole pool evenly. For example, cultured plankton, or made soy milk, can be evenly sprinkled throughout the pool. The advantage is that it eliminates the hassle of setting up a bait table, so that the whole pool of tadpoles can eat the bait nearby. Its disadvantage is that it is difficult to grasp the actual amount of bait for tadpoles, and when it is overfeed, the sinking residual food spoils and spoils the water quality.
(3) Time, frequency and quantity of bait. It varies from place to place, time, tadpole and so on. Tadpoles 3 to 5 days after hatching are the starting time of feeding. The number of baits is generally 1 to 2 times a day, 9-10 a.m. and 4-5 p.m.
(4) The amount of bait thrown. It is generally proportional to water temperature, tadpole age and body weight. However, the water temperature is too high (above 35 ° C), and the amount of bait is reduced at some times during the peak period of tadpole metamorphosis (forelimb growth, tail atrophy and disappearance). The types of baits to be fed, the initial stage of the ant can preferably be put into the culture of plankton, the middle and late stage can be fed with compound feed (the ratio of animal feed to plant feed is 1:1 or 2:3). The daily amount of bait per 10,000 tadpoles is: 5 to 30 liters of grasshopper culture solution for 5 to 10 days old, or 1 to 2 egg yolks with 1 to 2 kg of water to make a filtered suspension. 11 to 30 days old into live fleas or with food 0.1 to 2 kg. After 30 days of age, 2.1 to 12 kg of mixed bait are put in. Changes in the type of bait and the amount of bait thrown should follow the principle of gradual change. Tadpoles have the habit of overeating after starvation, and must prevent indigestion caused by indigestion caused by sudden changes in the bait, and even suffer losses due to death. Always check your food after the last bait to decide how much you'll take next time. If there is a surplus last time, the next time it is necessary to reduce the amount appropriately, if it is eaten soon, it should be increased as appropriate.
(5) Management. In addition to feeding, it is especially necessary to create a good ecological environment for tadpoles, and there should be waterweeds such as water hyacinth, duckweed, and goldfish algae in the pond (about 1/2 of the water surface). In addition, additional administrative work is required.
1) Regularly patrol the pool and make good records. Every morning and evening, it is necessary to inspect the breeding pond, timely record the temperature, water temperature, water quality, tadpole living conditions (if there is no floating head phenomenon, the last bait leftovers, etc.), and find problems to deal with in time. For newly hatched tadpoles and tadpoles at the peak of metamorphosis, special attention should be paid to observation and management.
2) Control the water temperature and water level. The most suitable water temperature is 23 ~ 30 ° C, if the water temperature is higher than 35 ° C, it is necessary to change the water in time. Drain 1/4 to 1/2 of the original pond water and introduce clean water with a lower water temperature. If the water quality is polluted, similar water exchange measures need to be taken. The water level should generally be maintained at a depth of 40 to 60 cm. When raising small tadpoles or the water temperature is low, the water level should be lower, and on the contrary, it should be higher.
3) Control water quality. The water quality of the tadpole pond should be clean, the dissolved oxygen in the water should be higher than 3 mg /l, the salinity should be less than 2 ‰, and the pH should be between 6.6 and 8.2. The quality of the water can generally be estimated by looking at the color of the water.
Lean water: the water is more transparent and there are fewer plankton in the water.
Fertilizer water: light yellowish brown with green, less turbidity, more diatoms, golden algae, yellow algae in the water, and some green algae. Yellowish brown, less turbid, mainly containing diatoms in the water. Oil green, less turbidity, the water is mainly cryptoalgae and chlorella, generally with fermented manure applied to the pond water more often show this water color.
Sick water: red with brown, cloudy. The water contains a large number of multiplying red algae, which the tadpoles do not digest after eating, and pollute the water quality, so that the tadpoles are poisoned. The rescue method is to remove the tadpoles in time and then clean up the pond.
Deterioration of water quality (diseased water): In addition to being caused by the excessive reproduction of some plankton, it can also be caused by the fermentation of organic matter, the rotting of food residues, the lack of oxygen in the water, the pollution of water sources by industrial and domestic water, the decay of the body due to the death of diseases and insects, and the spread of pathogens.
Once the phenomenon of water pollution deterioration is found, it is necessary to change the water, do not suddenly make the water temperature difference too large when changing the water, generally the amount of water exchange is 1/4 to 1/2, and pay attention to mastering the water change time. Farmed tadpoles are best placed in fertile water and fatter water, and in the case of artificial baiting, it is also possible in lean water.
4) Often keep the pool water clean and hygienic, and find that there are suspended debris, floating film, dead tadpoles, etc. on the water surface, and should be fished out and treated in time. The bait table should be removed and washed frequently, disinfected with bleaching powder or sterilized by daylight exposure. The food left on the bait table after the tadpole is eaten should be removed in time to avoid rotting in the pool water, and after several months of rearing, the bottom of the pool should be removed in time if there is sludge and food residue that sinks after sprinkling.
5) Conscientiously do a good job in the prevention and control of tadpole diseases and insect pests and the breeding and processing of tadpole bait.
6) Carefully inspect the maintenance facilities. Frequently inspect and repair drainage and irrigation equipment such as water pumps to keep them in good condition for use at any time.
7) Timely treatment of tadpoles with serious floating head phenomenon. It is normal for tadpoles to move vertically up and down the water, or to swallow floating bait on the surface of the water, or to float on the surface for a long time, or to be inactive, or to be hypoxic or sick.
When the water temperature is high (such as July to September of each year), tadpoles generally float on the surface of the water around dawn, indicating that the dissolved oxygen in the water is insufficient, forcing the tadpole to float to the surface of the water to absorb more oxygen. If the head is no longer floating after sunrise (about 7-8 a.m.), it is not a big problem. If the weather is unusually hot and stuffy, the grasshopper floats in the first half of the night, or even in the evening, indicating that the water is very hypoxic, the water quality deteriorates, and the water must be changed immediately or the oxygenator must be opened to increase the dissolved oxygen of the water. Or sprinkle bleach powder (to bring the pool water to a concentration of 1×10-6) to kill the over-propagated plankton and bacteria in the water. If rescue measures are not taken in time, it may lead to a large number of tadpole deaths, or even the whole pool is left.
8) Timely do a good job in sub-pond breeding and maintain appropriate stocking density. In general, the rearing density of tadpoles that have just hatched to 10 days old is 2000 to 1000 fish per square meter, 11 to 30 days old is more appropriate to 1000 to 300 tails, and the stocking density of 30 days old to 300 frogs before metamorphosis is 300 to 100 frogs. The determination of density is related to tadpole growth period, body size, bait supply status, management level and other factors, which can change according to time, place and specific conditions.
Stocking density from dense to sparse change, often through the division of the pond to achieve, when the tadpole from one breeding pond to another pond breeding, pay attention not to cause a sudden change in ecological conditions, so as not to cause disease losses, such as water temperature changes do not exceed 1 ~ 2 °C. Changes in environmental conditions should be gradually changed within the tolerable range. Especially in the dense state of tadpoles transported over long distances, it is necessary to pay more attention to this when they are first raised in the breeding pond.
9) Do a good job in the management of tadpole wintering. Under the natural conditions of temperate areas, the overwintering period is generally entered from November to March of the following year, and the pool water should be maintained at this time for more than 1 meter. In this way, the bottom water temperature is maintained at about 5 °C, and even if the surface water is frozen and snow accumulates, the tadpoles can safely overwinter. Hydration and oxygen replenishment equipment and measures should also be prepared. If the water level drops, the water temperature decreases, the bottom sludge is fermented and lacks oxygen, it can be filled and inflated in time. It is best to clean up the sludge at the bottom of the pond before winter to reduce oxygen consumption. If there is no aeration equipment, a certain number of ice holes can be excavated on the ice surface, and then new ice cubes in the ice caves can often be removed to make contact with the water and air, thereby increasing the dissolved oxygen volume of the sub-ice pool water. It is also possible to often clear the ice area and snow, increase the daylight transmittance, so that the phytoplankton suitable for low temperature water can grow and reproduce, and increase the dissolved oxygen amount of water through photosynthesis.
Ponds with temperature control conditions, the water temperature should reach more than 15 °C, it is best to control at 20 ~ 30 °C, then the winter management is not much different from summer and autumn, tadpoles can still grow and develop under good conditions and metamorphosis.
The feeding and growth and development of bullfrog tadpoles at different developmental stages are shown in Table 4.
Table 4 Feeding, growth and development of bullfrogs
2． Rearing management of juvenile frogs
Juvenile frogs refer to bullfrogs that mature sexually after the tadpole completes metamorphosis landing, including juvenile frogs, small frogs, and young frogs. Its body size varies, under general feeding conditions, the weight of young frogs ranges from a few grams to 50 grams, small frogs are mostly 51 to 100 grams, and young frogs are mostly about 101 to 250 grams. Weight is only one of the reference indicators for the classification of juvenile frogs, and there is no strict distinction, it often varies with growth and development period, environmental conditions, nutritional health and other factors. Young frogs grow and develop very quickly, strong ability to adapt to the environment, but the ability to resist cold is not as good as tadpoles, male and female are also difficult to distinguish, bullfrogs are mainly meat-eating, such as insufficient supply of bait, often appear young frogs swallow young frogs and tadpoles, so feeding management should be strengthened.
(1) Feeding. Bait is thrown 1 to 2 times a day on the bait table, 9-10 a.m. and 4-5 p.m.
Newly metamorphosed young frogs, which only eat live animals, must be put into live bait and gradually trained to eat dead bait. The ratio of live bait to dead bait for 1-month-old frogs (calculated from the completion of metamorphosis) is 2:1, and 1.5-month-old frogs are 1:1, and all 3 months old can be fed dead bait. The size of the dead bait is suitable for the juvenile frog to swallow in one bite, if it is too large and difficult to swallow, it may compete with each other, consuming time and energy to eat bait, which is not conducive to the growth and development of juvenile frogs. The protein content in dead bait (including compound feeds) is about 40%.
The amount of bait thrown above is appropriate to eat the amount of bait put in the previous time, and it should be mastered as appropriate. Generally speaking, with the growth of juvenile frogs, the increase of water temperature, the amount of bait should be gradually increased, usually the amount of daily fresh bait is 5% to 15% of the weight of juvenile frogs, equivalent to 1% to 3% of dry material.
The types of live bait and dead bait should be determined according to the status of breeding bait, bait resources and seasons in various places, and the bait should be diversified, rich in nutrition to meet the needs of the growth and development of juvenile frogs, and the price is low. From the current point of view, to supply a large number of juvenile frog bait, the more reliable way is to vigorously carry out the artificial breeding of earthworms and yellow mealworms, snails, and maggots, purchase scraps from nearby slaughterhouses and food factories, produce or purchase artificial compound feed, and use black light lamps to lure insects. Feeding juvenile frogs with earthworms, both in the wild and in indoor ponds, grow quite rapidly.
Bullfrogs are not born to eat dead bait, and must insist on training from the beginning of the frog to better develop the habit of eating dead bait. There are many training methods, and here are a few examples:
1) Method of feeding dried pupae. The silkworm pupae are soaked in warm water until soft, and then put a slanted board at the top of the wall to the side of the young frog pond, and the top of the board is placed on the dried silkworm pupae, when the silkworm pupa rolls into the water along the sloping board, at first the young frogs feel frightened and dare not eat, but insist on continuing to feed in the same place and in the same way, the young frogs gradually adapt and begin to feed, after eating habits, the silkworm pupae can be stacked on the lower end of the slanted board, and the young frogs can also jump to the board to swallow the dried silkworm pupae.
2) Method of feeding animal offal. Holding a fishing rod in hand, the end of the line is tied to the animal's internal organs (only a small number of cuts are connected), and every day at a fixed location, the bait moves up and down 15 cm above and below the water surface. At first, the young frog did not dare to approach, but Jiuzhi was tempted to swallow. After tasting the taste, they rushed to grab food. Animal offal can also be placed in the bait table, each time placed at a regular place on the edge of the pool, the bait table half sinks into the water, half exposed to the water. Place several loaches (or small fish) in the bait table at the same time. The loach stirs in the bait table, causing the young frogs to mistakenly believe that it is live bait, desperately come to grab food, and do not release the loach after eating, and the young frogs will also enter the bait table to eat. You can also install a water pipe above the bait table, so that the water drops drop by drop in the bait table, the vibration of the water makes the dead bait fluctuate in the stage, the young frogs mistakenly think that it is live bait and grab the food in groups, and after developing a habit, they do not drip water. At the beginning, puffed bait, loach, small fish, etc. can also be placed together in a 3 to 5 cm deep groove bait table, and the young frogs can be trained to enter the groove to eat the floating puffed bait.
The above methods are the use of young frogs born to eat live bait, visual sensitivity to active objects, so that young frogs mistakenly recognize dead bait as live bait and swallow, when many times taste the delicious taste of dead bait, timed, fixed point bait some stimulation becomes a signal, so as to develop a new habit of eating dead bait. As long as this principle is mastered, bullfrog farmers can also explore more new methods according to their own situation, and train young frogs with more advanced and scientific methods to further improve the level of breeding.
In the bait, if it is found that bullfrogs have not eaten for a long time after moving into a new environment, the cause should be checked, and if it is not caused by pests and diseases or noisy and unsuitable environment, the forced feeding method should be adopted. That is, catch the juvenile frog, open the upper and lower jaws, force the bait into the frog's mouth, so that it swallows, when the taste of the bait, the juvenile frog can automatically feed.
In the bait, it is not advisable to use other types of frogs as bait, otherwise, it will promote the habit of cannibalism between juvenile frogs.
(2) Management. The daily management of juvenile frogs is similar to the management of tadpoles, except for the emphasis on creating a good aquatic and grassy environment for juvenile frogs, the other summaries are described below.
1) Control the water temperature. The most suitable water temperature is 23 ~ 30 ° C, if the water temperature is higher than 30 ° C, cooling measures must be taken, such as partial water replacement, pergola and so on.
2) Control water quality. The most suitable pH is 6 to 8. It is necessary to remove the remaining bait frequently and remove dead frogs, rotten plants, floating membranes and other foreign objects. If the water is contaminated, replace or disinfect the water to keep it clean. Juvenile frogs mainly breathe in the lungs, although the requirements for water quality, especially the oxygen content in the water, are not as strict as those of tadpoles, but they cannot be ignored.
3) Control humidity. Always keep the land moist, plant crops or build sheds to protect from bright light.
4) Timely classification and pool management. Juvenile frogs grow and develop rapidly, and individual differences are large. In order to raise and manage more scientifically and avoid large frogs eating small frogs, after each period of breeding, it is necessary to classify and manage according to individual size and ponds. The breeding density should be appropriate, generally within 40 days of the age of the young frogs, about 150 to 100 per square meter, after 40 days of age of juvenile frogs, about 100 to 20.
5) Often do a good job in the prevention and control of pests and diseases and natural enemies. Rats are a natural enemy of minors. Some juvenile frogs overwinter ponds (30 square meters) are killed by rats every day in a week on average, and more than 40 can be killed in one night, and the most can bite more than 110 in one night.
(3) Wintering management work. When the water temperature drops to 6 °C and the temperature is about 10 °C, the juvenile frog enters a hibernating state. Before and after hibernation, it is necessary to do a good job in the winter management of juvenile frogs.
1) Preparation and management of underground hibernation: Juvenile frogs often overwinter in moist poolside caves and tree root gaps 30 to 40 cm from the frozen layer. According to this habit, before wintering, juvenile frogs are artificially provided with wintering conditions and some wintering methods are created.
Cave overwintering: Dig loose soil around the juvenile frog pond, and dig several caves with a diameter of 13 cm and a depth of 1 cm in the sun to avoid the wind and 20 cm from the water surface, the cave should be kept moist, but the pool water should not be allowed to flood the cave. Juvenile frogs automatically burrow into burrows to overwinter before wintering.
Plastic shed overwintering: At a height of 30 cm above the water surface of the juvenile frog pond, cover with plastic film to protect the bullfrog from wintering. You can also use bamboo or steel to build an arched or herringbone-shaped shed on the pool, the roof of the shed is about 2 meters from the ground, covered with 2 layers of plastic film, connected with the pool side into a sealed insulation cover, surrounded by mud to seal the film, the film is best covered with another layer of estophobic net, in case the wind blows the film out. If the outside temperature drops below 0 °C, another layer of straw curtains can be covered with the film. On sunny days, open the grass curtain to allow sunlight to heat up, so that the temperature of the overwintering pool is maintained above 10 °C. When the temperature rises in the spring, the plastic film is gradually uncovered to circulate the air and not overheat.
Barrel overwintering: When breeding bullfrogs in small quantities, bullfrogs can also be placed in tanks and barrels for wintering. The specific method is: first fill the cylinder or bucket with some soil, the middle is high, the surrounding is low, and it becomes a steamed bun shape. Water is appropriately released around the low concave area to moisten the soil in the high places, and there is a small amount of standing water around it. After the bullfrog is placed in the tank or barrel, it is covered with aquatic grass or turf, and the lid of the cylinder mouth is covered with grass curtains or sacks and cotton wool to prevent the frog from escaping. The cylinder and barrel are surrounded by grass for heat preservation. If the temperature in the cylinder or barrel is too low, a lamp can be installed in the cylinder or barrel to heat it, or the plastic bucket can be filled with hot water and placed in it for appropriate heating.
2) Deepen the water layer overwintering: Before wintering, the water level of the juvenile frog pond is deepened to more than 1 meter, because the original 30 to 50 cm thick sludge under the frog pond, the bullfrog will drill into the sludge by itself. One of the sludge has thermal insulation performance, and the other is due to fermentation exothermic heat, which can increase the water temperature by 2 °C. In this way, bullfrogs can also overwinter safely in deep-water sludge.
3) Other wintering methods: as long as it provides 6 ~ 12 ° C (water temperature or temperature) in winter, humidity, a certain amount of oxygen (included in air or water), invincible environment, juvenile frogs can safely overwinter. There are many ways to overwinter in indoor brick pools, hot spring water, and circulating warm water.
During the wintering process, juvenile frogs do not eat and do not move, close their eyes and breathe slowly in the lungs, and even in low temperature water, only the skin for low-level gas exchange. If the ambient temperature rises to more than 10 ° C, the juvenile frog can wake up, breathe stronger, begin to move, and even eat, at this time it is advisable to supply some bait or try to cool down, so that it can enter a dormant state again. Dormant juvenile frogs should keep their environment quiet, especially to prevent predators, such as the harm of rats, because juvenile frogs at this time have no ability to resist predators. During the wintering period, it is necessary to check the overwintering situation often, and if there are dead frogs, it should be removed in time, such as the discovery of diseases such as red leg disease, and timely treatment should be carried out to prevent the spread of infection.
3． Rearing management of adult frogs
Juvenile frogs are raised for about 1 year and reach the stage of sexual maturity, that is, adult frogs. At this time, adult frogs generally have a body length of about 11 cm and a weight of 250 to 300 grams, and the largest body length is 12.7 to 20.3 cm and a weight of about 500 grams. After raising these adult frogs for a period of time, some are selected as breeding frogs (brood frogs), and the rest can be sold as edible frogs or processed. Therefore, the feeding and management of adult frogs is good or bad, which has a very important impact on the quality of breeding frogs and edible frogs.
(1) Feeding. Adult frogs have large individuals, large feeding, ensure adequate supply of high-quality palatable bait, control the appropriate ambient temperature, and their weight growth is relatively fast, and individuals gain 30 to 50 grams per month.
Adult frogs are raised similarly to juvenile frogs and will not be repeated here. Adult frogs that have been trained to eat dead bait are basically dead bait, except for a small number of live insects lured by black lights. For newly introduced wild stocked frogs, they are initially fed live bait like juvenile frogs, and at the same time gradually trained to eat dead bait.
The bait should be timed and fixed (at the bait table). The amount of bait thrown depends on the actual amount of bait eaten by the adult frog. It is usually fed once a day before dusk. The leftover bait on the bait table should be removed in time to prevent decay and pollute the water quality. Earnestly do a good job in disease prevention and control.
(2) Management. The management of adult frogs is basically the same as that of juvenile frogs. However, due to the strong mobility of adult frogs and their ability to jump, special attention should be paid to the maintenance of the wall to prevent escape.
The most suitable water temperature in the process of adult frog breeding is 23 ~ 30 ° C, and it is necessary to do a good job of shade to prevent high temperature and strong sunlight in summer. Sprinkle water frequently on land to keep it moist.
Adult frogs feed more and excrete more waste, so it is necessary to keep the water quality from pollution frequently. Generally in the hot summer, it is best to insist on changing the water once a day, the amount of water is 1/3, the temperature difference between the new and old water is 1 ~ 2 ° C, and it is necessary to avoid sharp changes in water temperature. The water discharged from the adult frog pond contains a large amount of frog manure and urine and food residues, which can be used for pond fish culture to enrich water quality.
The breeding density of adult frogs is generally 50 to 20 per square meter, and the density is adjusted as appropriate with the adult frogs and the management level of breeding, water temperature, water quality and other factors.
In the process of adult frog growth and development, the individual size varies greatly, in order to avoid adult frogs swallowing small frogs, it is best to breed adult frogs of different sizes in separate ponds at the appropriate time, and adjust the breeding density in time.
The overwintering management method for adult frogs is similar to that of juvenile frogs.
4． Breeding management of brooding frogs
Brood frogs are high-quality adult frogs that are selected for breeding and breeding and grow robustly. They are large individuals and generally weigh more than 300 grams. Although these broodstock grow slowly, they require a lot of nutrients to contribute to gonadal development. The quality and health of the management and health of broodstock farming have a decisive impact on their ovulation volume, fertilization rate and growth rate of commercial frogs, and must not be neglected. Rearing management is similar to that of adult frogs in general, and only the relevant matters that should be paid special attention to are briefly introduced below for attention.
(1) Feeding. Broodstock feeding is large, nutrition to fully meet the needs of growth and reproduction, generally each daily bait amount of 10% of body weight, bait types should be more, comprehensive nutrition, of which animal bait should not be less than 60%. The amount of feeding of the brood frog in estrus decreases, and the feeding volume is basically stopped when holding, spawning, and sperming, and then the amount of feeding is greatly increased, and the amount of bait should be increased or decreased according to the above situation.
Generally, bait is thrown once a day in the evening, and it is also necessary to fix and time, and often clean the baiting platform to maintain cleanliness and hygiene.
(2) Management. The pro-frog pond is not only a place for pro-frog feeding and living, but more importantly, it is a place for spawning and sperming, so the management work requirements are high, and the surrounding environmental conditions are suitable for both pro-frogs, fertilization of eggs and hatching of eggs.
1) The most suitable water temperature is controlled at 25 ~ 27 °C, and the suitable water temperature is 23 ~ 30 °C, otherwise, it will not be conducive to the growth, development and reproduction of broodstock frogs.
2) Keep quiet and avoid noisiness.
3) The water level of the pool is maintained at 15 to 40 cm, and its depth is related to maintaining a suitable water temperature, and the water should be changed frequently to ensure excellent water quality, and its dissolved oxygen, salinity, pH, biological composition, etc. should be suitable for egg fertilization and hatching. Because the pool water is shallow and the water temperature is volatile, it is necessary to be particularlyware of the harm of eggs caused by excessive water temperature in the heat.
4) The breeding density of broodstock frogs is generally 1 to 2 per square meter. A high density is extremely detrimental to reproduction.
5) After the parent frog lays eggs, the eggs should generally be carefully lifted out of the basin in time (within a few hours) (do not reverse the upper and lower positions of the eggs, and should not stir the egg blocks), and gently put them into the incubation pool (box) to hatch alone to strengthen management and protection and improve the hatching rate.
6) Beware of predators of all kinds of predators preying on the right brooding frog and laying eggs. Because the brooding frog is in a state of reproductive excitement, it is not responsive to the invasion of natural enemies, it is not convenient to move, and the ability to resist enemies is greatly reduced, while frog eggs are more likely to be swallowed by fish and other frogs and other animals.
7) Special attention should be paid to the wintering work of parent frogs (the method is similar to that of adult frogs).
8) Bullfrog spawning time and number is closely related to the local climatic conditions, when the water temperature rises steadily to more than 22 ° C, mostly spawn in the morning after rain and sunny, but there are also noon or afternoon spawning, should be prepared in advance, Table 5 is a breeding frog pond in the suburbs of Beijing in 1989 spawning statistics table.
Table 5 Statistics of spawning of species of bullfrogs
< h1 class = "pgc-h-arrow-right" > (v) shipping</h1>
With the development of bullfrog breeding, in order to introduce breeding frogs and supply domestic and foreign market commodity frogs, it is necessary to transport bullfrogs. The success or failure of transporting bullfrogs depends on the preparation of transportation and transportation technology, and if done well, the survival rate can reach more than 90%.
1． Transport of frog eggs
Newly fertilized frog eggs can be transported quickly, for a short time and properly under careful packaging, but because the egg is easy to adhere to and damage, there are still not many in China.
2． Transport of tadpoles
In the mountainous areas with neither waterways nor roads, the shoulder-to-shoulder transport method is used; if it is transported over long distances, it can be transported by car, train, plane and other means of transport.
(1) Shoulder pick transport method. The picking tools are simple and vary from place to place, most of which are fish baskets and buckets. Each person picks two buckets (baskets), and the pickers rhythmically flutter through their shoulders during the pick-up, so that the water in the buckets (baskets) fluctuates regularly with the pace, thereby increasing the amount of dissolved oxygen in the water. Fish basket water should not be too much, the water depth of about 16 cm, the density of the tadpole, generally within 1 to 2 days of the trip, each carton can be loaded with 800 to 1500 tadpoles. The body length of 3 to 5 cm can be loaded with 1500 tails, 6 to 8 cm can be loaded with 1000 tails, and more than 8 cm can be loaded with about 800 tails. Winter transport, water temperature drops, density can be appropriately increased, the picker must have a wealth of experience, in order to reduce the mortality rate in transport. It is best not to stop oscillating on the fishing basket when resting. If you spend the night on the way, the tadpoles should be kept in cages in the pond, and the bait can be thrown before the next day's transportation, and cannot be fed during the pick.
(2) Automobile Transport Law. The shipping containers used in automobile transportation include wooden barrels, tarpaulin baskets and canvas barrels. Each car is loaded with containers ranging from 4 to 6, separated on both sides of the car. During the transportation process, the water should be changed regularly to remove the tadpoles from casualties in time.
At present, the best way to transport tadpoles over long distances is to oxygenate and cool down the nylon bag, and the specifications of the nylon bag are generally 90 cm long and 50 cm wide. When shipping, first fill 1/3 of the water, then load into the tadpole, and immediately fill with oxygen, until the bag is slightly expanded, and then tighten the mouth of the bag, and check whether there is water leakage or air leakage at the ligation of the bag mouth. Nylon bags should be packed into cartons or wooden boxes, so as not to damage and break, the appropriate density of shipment, 40 to 60 tadpoles loaded with 3 to 5 cm per liter of water, 25 to 30 tails of 6 to 8 cm long, and 15 to 20 tails of more than 8 cm. If the tadpole can reach its destination within 20 hours, it can no longer change water and oxygenate on the way. Tadpoles at the peak of their metamorphosis are not suitable for shipment because they are in a period of change in physiological habits.
The above method is also suitable for train transportation, but it must be noted that the water should be properly changed and oxygenated every day.
(3) Aircraft Transport Act. Air freight is characterized by fast speed, high shipment density, and significantly shorter transit time than other transportation methods. Its disadvantages are mainly the large load capacity and the inconvenience of changing water. The management method is much the same as other methods, and the air freight method is described as follows:
Fill 70% water with plastic fry buckets, put in tadpoles, add compressed pure oxygen, and seal transportation. Depending on the length of the transport time, the amount of compressed oxygen also varies. The pressurized oxygen seal begins before take-off and opens upon arrival at the destination. Such transport laws do not require care during air transport.
No matter what method of transporting tadpoles, it is necessary to choose a suitable season, such as summer transportation, pay attention to cooling, and winter transportation should keep warm and warm. When changing water, the water temperature difference should not exceed 2 ° C, the water is preferably a pool water with good water quality, river water or well water, and can not use seriously polluted water, as well as freshly released tap water. When tadpole hypoxic floating head is found, it can also be sprinkled with fast-acting oxygenators in time.
Before the tadpoles are shipped, they should be intensively kept in the pond or cage for 6 hours to 1 day, so that they can drain the feces and adapt to the dense life during transportation.
3． Transport of juvenile frogs
Transport juvenile frogs, you can use moisturizing, breathable, smooth, anti-escape containers, such as plastic barrels, boxes, basins, bags, or wooden boxes, tin boxes, etc. At the bottom of these containers, put some aquatic grass or damp cloth, and have ventilation holes on the sides. After the juvenile frogs are placed, they are covered with wet kapok or gauze, and the container is covered and shipped. When transporting long distances, it is necessary to often give juvenile frogs water and pay attention to maintaining a suitable temperature. The transport density of juvenile frogs, according to the size of individuals, is 200 to 2000 per square meter. If shipped in plastic boxes, each box can also be stacked in several layers to improve transportation efficiency.
4． Transport of adult frogs
The transport method of adult frogs is similar to that of juvenile frogs, but because adult frogs are large and have strong jumping power, it is advisable to divide them into small rooms in containers, fill them with wet aquatic grass or wet cloth, and put 3 to 4 adult frogs in each small room. It is best to put each frog into a small gauze bag, the gauze bag should be soaked, and then put the small gauze bag into each small room, covered with a small amount of aquatic weeds, and then covered. This prevents adult frogs from jumping and getting injured, and also prevents bullfrogs from crowding each other and stacking them to death. Using the previous method to load frogs, and stacking plastic boxes, airlifted several kilometers, 130 pairs of bullfrogs died only 1 pair, the survival rate of more than 99%. If each adult frog were isolated using the latter method, the casualty rate would be lower. For long-term transportation, we must pay attention to frequent water, heat preservation, ventilation, and prevent strong vibrations. Adult frogs should stop feeding 2 to 3 days before they are transported to prevent feces from polluting the environment inside the transport container.
<h1 class = "pgc-h-arrow-right" > (vi) intensive farming</h1>
Intensive breeding bullfrog has the advantages of short breeding cycle, high yield and stable yield, land saving, water saving, labor saving, etc., which are substantially different from conventional breeding, and can effectively exclude the influence of unfavorable natural factors, under the condition of changing the bullfrog only eat live bait, after 5 months of feeding, each square meter can produce about 10 kg of commercial frogs.
1． The conditions for intensive culture are required
(1) Intensive breeding of frog pond area should be small and not large, the general area and survival inversely proportional, each pool area to 3 ~ 6 square meters more suitable, frog pond with cement brick concrete structure, pool height of 0.6 ~ 0.8 meters, and with drainage and irrigation equipment and anti-escape measures.
(2) There is a suspended feed table in the pond, and the feed station area accounts for more than 50% of the pond area, which can be used for frog activities or feeding, which is conducive to high-density breeding.
(3) Abnormal shallow water feeding, the normal water level in the frog pond is generally 0.2 meters, if the three-dimensional breeding is carried out, a grape rack can be set up on the pond, which not only creates good ecological conditions for the bullfrog but also uses the space difference to increase the benefit, and the water level in summer does not have to be increased under shaded conditions.
(4) Intensive feeding is an important measure to accelerate growth and meet the nutritional needs of bullfrogs.
(5) Intensive breeding of bullfrog water quality requirements are not too strict, the general pH of 6.5 ~ 8.5 can be adapted, the water body contains a slight chlorine gas will not affect the growth of bullfrogs, so you can directly add tap water. When using pool water, there should be a filtration device to prevent the invasion of germs and predators. And there should be sunlight into the pool, sunlight is an important way to ensure the normal development of bullfrog bones, if there is no sunlight can also be supplemented with incandescent lamps.
(6) Intensive breeding bullfrogs should be stocked with more than 20 grams of frog species, and frogs below 20 grams can be cultivated in conventional ponds, such as relay breeding methods, tadpoles can also be stocked in intensive ponds, using this method, the number of free-range tadpoles per square should not exceed 200, and it is not advisable to feed animal bait too much, so as not to make the metamorphosis young frogs too small.
2． Management of intensive aquaculture
The key technique of intensive frog farming is to domesticate bullfrogs to eat commercial feed, and the basic method is to achieve appropriate methods, suitable feed, suitable density and suitable temperature.
Bullfrogs have the nature of eating live bait, but this is not caused by the physiological characteristics of its eye area is too high, through experiments to confirm that the use of conditioned reflex principle, it is possible to domesticate all bullfrogs to eat dead bait, the specific method is:
(1) In the intensive frog pond, the method of timing, positioning, timing and fixing is adopted, so that bullfrogs clustered in high-density environments have no choice but to accept artificial feeding. According to the results of the experiment, the domesticated bullfrog ate dead bait, not by individual size, but only by the palatability of the feed. Feed for bullfrogs of more than 20 grams is more readily available, so it is advisable to domesticate bullfrogs with juvenile frogs of more than 20 grams.
(2) At the beginning of the frog's entry into the pond, due to the temporary inability to adapt to the new dense environment, it can not be fed for one or two days after entering the pond, and domestication begins on the third day. Fresh small trash fish can be used as feed for domestication, and the size of the feed fish is limited to a length (from the tip of the mouth to the tip of the tail) not exceeding 1/2 of the length of the bullfrog's crouched body, and its width is smaller than the frog's mouth fissure. Keep 1 to 2 cm of shallow water on the feed table, so that the small miscellaneous fish put in are slightly floating, the amount of feeding for the first two days of domestication should not be more, some live fish and shrimp can be mixed to lure, and then gradually reduce the amount of live bait to increase the amount of dead bait, until the formation of a fierce group food effect, all eat dead bait, domestication time is generally about 1 week.
(3) Domestication of dead bait must be in a high-density stocking state to show effect. The initial weight of 20 grams of juvenile frogs is about 200 per square meter, when the individual reaches 50 grams, the density is about 120 per square meter, when the individual reaches 150 grams, the density is about 60 per square meter, and when the individual reaches more than 300 grams, the density does not exceed 35, basically reaching the saturation density. The density is too thin, which is not conducive to domestication and feeding, and the density is too large, which will reduce the normal activity space of frogs, causing mutual intrusion between frogs and frogs, affecting normal growth.
(4) Bullfrog is a thermotropic cold-blooded animal, temperature has an important impact on the metabolic function of bullfrog, frog feeding intensity with the rise and fall of temperature. The water temperature is below 18 °C and is not easy to domesticate. The most suitable water temperature for domestication to eat dead bait is 20 to 30 °C, and when the water temperature is lower than 15 °C or above 33 °C, bullfrogs eat less or even do not eat.
(5) Domestication feeding should flexibly adjust the daily feeding rate according to the size of the frog, between 6% and 7.5%. The metabolism of the juvenile frog stage is vigorous, multiple feeding can be implemented, the daily feeding rate is relatively high, and the adult frog stage grows the fastest when it weighs 150 to 200 grams. In seasonal order, from april to August harvest of commercial frogs, the average frog weight can reach 300 grams in 5 months.
(6) If the feed of intensive frogs is mainly based on small trash fish, each 4.5 kg of fresh feed can grow 1 kg of frog meat, and dry small trash fish can also be fed, but its quality is not as good as fresh food, and every 3 kg or so of dried fish can grow 1 kg of frog meat. If you change from feeding fresh fish to dry fish in the middle of the feeding process, you must have an adaptation time of 5 to 7 days.
(7) Intensive frog raising, bullfrog growth rate is fast, grading management is an important measure, each group of pond bullfrogs, interval 20 to 30 days according to the large, medium and small grading adjustment once. Long-term size polyculture, individual disparity is too large, once the feed shortage, that is, the phenomenon of large frogs eating small frogs may occur, in a dense environment, even if the feeding amount is quite sufficient, weak frogs will also show fear and timidity in front of strong frogs.
(8) The feed of intensive breeding is as diverse as possible to meet the nutritional needs of bullfrogs for protein, amino acids, vitamins and minerals. In addition to fish, fresh feed can also be fed into strips of animal offal, mussel snail meat, eel head and tail, etc., dry feed in addition to dried fish can also be fed dried shrimp, silkworm pupae and artificial pellet feed.
(9) Intensive breeding of bullfrogs, feed intake is large, excrement is relatively large, coupled with some residual bait sinking into the water to pollute the water quality, so the breeding pond water should be replaced frequently. Spring and summer generally change the water once every 3 to 4 days, change the water once a day in the summer, and when the temperature reaches more than 35 ° C in the middle of summer, add some water at noon.
3． Ecological characteristics of intensive farming of bullfrogs
In the case of wild release or pond free range, bullfrogs have habits such as burrowing, nocturnal outflow, feeding activities, etc. Under intensive breeding conditions, some of the life habits of bullfrogs have undergone great changes, and gradually adapt to high-density stocking, artificial baiting, etc.
(1) Ecological adaptation characteristics. The activity of bullfrogs in intensive breeding ponds is limited to the bait table and the water, which not only has less energy consumption, which is conducive to rapid growth, but also very conducive to the domestication of bullfrogs. When the temperature reaches above 22 ° C, the bullfrog crouches on the bait platform day and night, only occasionally entering the water to moisten the body, and when the temperature rises to 34 ° C, the bullfrog all leaves the bait table and floats in the water next to the bait table to avoid the invasion of high temperatures. Avoiding the midday heat and feeding bait in the morning or evening, bullfrogs can still feed normally. During the summer high temperature period, the frog pond is shaded by scaffolding plants, the water level of the frog pond is raised to 3 cm, and the frog pond is flushed with tap water at a temperature of 17 ° C every night, and the new water can be replaced to meet the cooling needs of bullfrogs. When tap water sprayed onto the bullfrog, the bullfrog did not shy away. Throughout the summer, bullfrogs in intensive breeding ponds can feed normally and have not seen summer sleep.
In early spring and late autumn, when the temperature drops to 18 ° C, bullfrogs enter the water to escape the wind and cold, and in general, the water temperature in this season is about 2 ° C higher than the temperature. On a clear day, the sun shines into the frog pond, the temperature rises to about 20 ° C, and the bullfrog can still feed in small quantities. When the temperature drops to 5°C, bullfrogs dive into the bait table to dormant underwater, but still occasionally move slowly. In winter, the water level of the frog pond is increased to 40 cm, no bedding is added to the bottom of the water, the water temperature is maintained above 3 ° C, and healthy and disease-free bullfrogs can directly overwinter in the cement pool. According to experiments, when there is about 3 mm of thin ice in the frog pond, more than 50 grams of young frogs can also drill out of the ice hole and emerge from the water surface. In cold weather, adding plastic film to the cement pool can increase the temperature in the cement pool to more than 5 ° C, and on sunny days, the plastic film needs to be removed, if the plastic film is not removed, some bullfrogs lying on the bottom of the water can be seen climbing on the bait table at noon.
Bullfrogs raised in intensive breeding ponds are docile in temperament. In the case of a pond height of less than 0.7 meters, without fenced facilities, not a single frog jumped during the 5-month breeding period. The larger bullfrog can even be touched by the breeder's hand and take a bait fish to reach the bullfrog, and the bullfrog dares to climb over and open its mouth to bite and swallow it. Bullfrogs have the adaptability of frogs in general. Perhaps, this is where the bullfrog has the advantage of being a farmed species.
It has been observed that bullfrogs have an instinctive strong demand for sunlight, especially in early spring or late autumn, the sunshine shifts, the light time is short, whenever the warm sunlight shines into the frog pond, all the bullfrogs in the pool are tolerant of each other, quietly crouching on the bait table to bask in the sun, at this time, if you feed it, most of them are dismissive.
Bullfrogs in intensive ponds are extremely sensitive to light and unresponsive to sound. When the bullfrog is basking in the sun, 2 meters away from the frog pool, shake it slightly with your hand, and throw your hand on the bait table in the shadow of the sun, you can make the bullfrog frightened and enter the water, but in the same case, 2 meters away from the frog pond to hit the iron basin, the bullfrog basically has no big reaction.
Pond culture bullfrogs, the body color is generally greenish brown, intensive pond bullfrog, body color is mostly brownish yellow or brownish black, which may be related to the cement pond wall and the color of the bait table is darker. If the bullfrog in the cement pond is placed in the pond, its body color can gradually fade and turn green after a few hours, and conversely, the pond breeding bullfrog is caught in the cement pond, and after a few hours, its body color gradually becomes darker and blacker.
(2) Feeding characteristics. According to some sources, bullfrogs, because of their special visual physiology, can "see" moving objects within a certain range but turn a blind eye to things that are stationary. It has been observed that the domesticated bullfrog can keenly see the stationary bait cast within 1.5 meters of it, especially for the habitual feeding, showing strong feeding initiative and flexibility. When the breeders approached the frog pond according to the fixed bait time, the bullfrogs in the pool waited in unison in the direction of the bait, and when the breeders spread the bait to the bait table in batches, the bullfrogs immediately launched a lively scramble. Some intercept it in mid-air without waiting for the bait to land, some leap across the partner in front of them to prey on the bait in front of them, and some even have the advantage of having their eyes high above their heads, unexpectedly turning 180 degrees and accurately biting the bait on the platform behind them. When feeding the bait to the small miscellaneous fish, some frogs bite a fish in their mouths, and they also use their forelimbs to step on the other fish in front of them to prevent other frogs from snatching it away. Bullfrogs, in particular, have a pair of forelimbs, as well as 4 little fingers that are webbed on the limbs, show amazing flexibility when feeding. If the bullfrog bites the tail of a larger bait fish, because the fish's penchant has barbed spines, the mouth is threatened, the bullfrog will use two forelimbs to help withdraw the tail from the mouth and change it to the middle of the fish, and the limbs of the two forelimbs will touch the head and tail of the fish one left and one right, and in a split second, the fish will be pulled into the head and tail facing outward. At this time, use the forelimbs to stroke the fish body a few times, adjust it into a straight line, and push it into the mouth.
Bullfrogs have been observed to have special vision for nocturnal feeding. If the bait time is postponed, the frogs are fed at dusk when the visibility is extremely low, the bullfrogs can still eat normally, and the remaining bait on the bait table has all disappeared for the next morning inspection. The bullfrogs in intensive breeding ponds are fed at a daily feeding rate of 6% per day, which can achieve the effect of meeting the feeding needs of bullfrogs without waste. If the amount of feeding is increased, the bullfrog generally no longer lingers, that is, it is a very suitable bait, and the bullfrog only bites at the edge of the mouth and plays with its forelimbs for a while, and then spits it out. There are also a few frogs barely overdose, but the next day's intake is significantly reduced, some frogs appear indigestion symptoms after overeating, the body is swollen like a round pumpkin, for several days lying on the bait platform do not eat and do not move, a few days later caused death.
Whether it is palatable or not has greater selectivity. Bullfrogs with small sizes swallow the larger bait of individuals, and even if they bite in the mouth for a long time, they can only spit out and give up, while bullfrogs with larger sizes will also show food refusal for bait that is too small for individuals. For example, bullfrogs of more than 250 grams, feeding small fish 3 cm long, also according to the daily feeding rate of 6%, feeding smaller than bullfrog mouth cracks, shorter than half the length of the bullfrog palatable bait, such as dried, fresh small miscellaneous fish, animal lungs (cut into small strips), etc., bullfrogs can eat 70% of the bait in about 15 minutes, and the remaining part can be automatically picked within 1 hour.
(3) Growth and sexual maturity. From juvenile frogs to adult frogs, the average weight can reach more than 300 grams, and the average monthly weight increase can reach 60 grams. However, bullfrogs in intensive breeding ponds must be graded regularly and in time, otherwise the gap between sizes will widen, thus affecting the overall weight gain effect. The small area of the intensive frog pond is designed to facilitate hierarchical management.
Intensive breeding ponds commonly see a phenomenon of film removal, that is, the whole body of the frog molts a transparent layer of membrane soft skin, when the film is removed, the frog quietly crouches on the bait platform or floats in the water, the two forelimbs slowly from the back to the head in front of the skin, and rely on the body's expansion and contraction, gradually remove the soft membrane to the toes of the limbs, until all off. This phenomenon of defilming continues to occur in the thriving frog population. The phenomenon of delamination decreases until it stops after entering winter. Sick and thin frogs do not see defilming. After dissection, it was found that when the intensively farmed female frog weighed 350 grams, her upper ovaries in the abdomen were only slightly larger than the broad beans, and they were still in a juvenile state. By the end of June, a small number of male bullfrogs that grew to more than 250 grams were found to be chirping. On summer nights, the chirping is frequent and regular, and every day around midnight, there is always a chorus that echoes each other. Females rarely chirp, and their calls are low, short, and unresonant. When the phenomenon of pairing occurs in intensive breeding ponds, the female frogs that are held under the male frog hoops make a snorting sound, and can still make a sound from the bottom of the water after sinking to the bottom. In the high-density environment of intensive farming, male and female bullfrogs only have a pairing action, and no spawning phenomenon is found.
<h1 class="pgc-h-arrow-right" > (vii) single-sex cultivation technique</h1>
The phenomenon that males grow faster than females in the commercial rearing stage of bullfrogs shows that unisexual (male) bullfrogs have their growth advantages, and further confirms that male bullfrogs not only grow faster than female frogs, but also frogs of the same weight, with high meat yield and large hind legs. Therefore, the cultivation of single (male) bullfrog seedlings is another way to improve yield per unit area and economic benefits. Male bullfrog seed rearing technology has the advantages of a wide range of sexual variation and a large range of effect doses than the cultivation of tilapia monosex fry. The cultivation method is to induce bullfrog tadpole to become all-male by methyltestosterin (MT for short). Its main practices are:
1． Induction of seed sexual degeneration
(1) Master the appropriate stage of taking the drug. For overwintering tadpoles or tadpoles aged 30, 20 and 7 days old in the current year, sexual transformation induction is carried out, the former is a sexually differentiated tadpole, with an average weight of 7.8 g/animal, about 1/3 of the tadpole hind leg cortex has been prominent, and some have grown hind legs. The latter three are tadpoles before sexual differentiation, and the weight of 7-day-old tadpoles is about 0.4 g/animal. Although the process of drug-induced sexual degeneration has an effect on the entire period of metamorphosis, including overwintering tadpoles, the effect is best to start taking the drug between 7 and 30 days of age. Because the tadpole is in the pre-sexual differentiation stage at this stage, the individual is small, the amount of feeding is small, and the drug can be saved relatively.
(2) Preparation of the drug: MT is dissolved in 95% alcohol, and then mixed evenly with the feed and dried for later use, about 1 time per week. The tadpole stage feed is mainly bran, rice bran and soybean cake flour. Mix 30×10-6 methyltestosterone in these feeds, such as 150 mg of methyltestosterone into a powder, dissolve in 95% alcohol (about 50 ml), and then mix well with 5 kg of feed to dry and set aside.
(3) Feeding method. Taking the 7-20-day-old tadpole as an example, the tadpole at this time weighs about 0.5 grams per piece, 5000 grams per 10,000 pieces, calculated by putting 4% of the feed amount, that is, feeding 200 grams of medicinal bait per day. Before 9:00 a.m., 2 to 3 shots are completed. As tadpoles grow, the feeding volume is adjusted appropriately every 3 to 5 days. After 20 consecutive feedings, the drug can be stopped and replaced by general feed.
(4) Fill fresh water with an appropriate amount. At the stage of administration, we should pay attention to changes in water quality and not make the water quality too fat, so it is necessary to fill some new water or change the water slightly. This can not only ensure that the tadpoles can eat the medicinal bait, but also prevent the floating head from dying. For the small pond cultivation method, it should be diluted in a timely manner.
2． Identification of sex-induced frogs
Based on experimental frog anatomical observations and section identification of sexually induced frogs, it was shown that with the increase of the number of days of administration, the sex ratio was positively correlated. Although male testicles have a variety of beginnings and vary in size within the same individual, they have no external morphology of the ovaries at all, so experimental frogs are regarded as all-male.
3． Observation of the growth of the unisexual bullfrog
Growth and living conditions: According to experiments in Fujian, the survival rate of the rearing experimental group after about 4 months in the seedling stage was 78.9%-93.3%, which was 15.59% and 4.78% higher than that of the control group, and the individual weight (growth rate) adult frog experimental group gained 125.1 grams, an increase of 45.4 grams compared with the control group's 79.7 grams, and the difference was obvious. The juvenile frog group took the 20-day-old as an example, the largest individual, the weight was 22.6 g and 22.2 g, respectively, and the control group was 19.4 g, with a weight gain of 16.5% and 14.4%, respectively. The smallest individuals differ by a factor of 1 and nearly a factor.
< h1 class= "pgc-h-arrow-right" > (viii) rice field farming techniques</h1>
1． Rice field conditions
The water source is guaranteed, the water quality is better, and the drainage is convenient. Of course, rice paddies on both sides of the shogou field and near the house are also available. In other words, rice paddies suitable for fish farming can also be bullfrog farming.
In order to make the field strong and not easy to be washed by the water, stone slabs were laid on the side of the field that leaned against the water. In order to prevent escape and manage the seine seine, the field is widened at more than 1 meter, the water depth is 6 to 15 cm, and the semi-dry rice is planted. One side of the paddy paving slab is dug with a depth and a width of about 80 cm, and the other three sides are dug with a depth and width of about 50 cm each to make the surrounding areas communicate.
2． Fenced off to prevent escape
Bullfrogs are good at jumping, up to 1.5 meters, so obstacles should be set around the rice field to prevent it from escaping, which is the key to the success or failure of breeding. Farmers can use 88 cm wide polyethylene mesh cloth, connected to a height of 1.76 meters, and set bamboo piles to enclose the rice field, and the lower end of the mesh cloth is buried in the soil for more than 15 cm. Linoleum, bamboo, asbestos board can also be used, but through practice, it has been proved that the polyethylene mesh cloth is well ventilated, and it is not easy to blow the fence down or wash down when it is windy and rainy, it is durable, convenient to construct, low cost, and tight fence.
The area of the paddy field can be large or small, and all localities should be arranged according to local conditions, from tens of square meters to 3500 square meters, and vegetables, grapes, sugar cane, corn, sweet potatoes, taro, etc. should also be planted in or around the padded field to provide more land places for bullfrogs. In this way, rice paddies provide a habitat for bullfrogs, which prey on a large number of pests in the field and fatten the field with excrement.
3． Seed stocking
10 days after planting, about 2,000 young frogs are stocked per acre, each weighing about 50 grams, in order to avoid large frogs eating small frogs, the individual differences in stocking frogs should not be too disparities. Bullfrog tadpoles should not be stocked in rice fields, because there are many predators in rice fields, such as yellow eels, carp, grass carp, crucian carp, etc. will eat tadpoles. While the rice field is stocked with bullfrogs, some carp, crucian carp, flowers, silver carp and other polycultures can also be stocked.
4． Feeding management
10 days after planting, the young frogs are stocked so that the young frogs can adapt to the living environment of the rice field as soon as possible. However, at this time, there are few insects in the rice field, bullfrog food is lacking, which requires feeding bait, that is, finely cut pig lungs or small trash fish, regularly sprinkled on the water surface of the protective ditch, you can also lay a piece of polyethylene mesh cloth on the bamboo products as a bait table, put the bait table into the water surface of the protective ditch, and then, the finely cut pig lung or small trash fish is sprinkled on the polyethylene mesh cloth, so that the time to supplement the bait is about 1 month. After the harvest of rice, although the number of insects that bullfrogs prey on rice fields has gradually decreased, because crucian carp in the rice fields are self-generating and multiplying, there are more small fish, and bullfrogs will not lack food.
In the protective ditch, maintain a certain amount of duckweed, small greenweed, purple-backed duckweed, etc., to ensure the bait of grass carp. Duckweed is also the bait for young frogs, and after fermentation with a small amount of lime in cow and pig manure, it is sprinkled in the rice field irregularly according to the color of the water and the growth of rice grass.
At least 10 cm of open space is set aside on both sides of the fence, keep no weeds, insist on patrolling morning and evening, check whether the fence is tight, and if there is a gap, it should be repaired in time to prevent escaping frogs.
5． Economic benefit analysis
Bullfrogs are cultured in rice fields, according to the effect of Sichuan Province, stocking in that year, harvested in October-November of that year, harvested 1500 to 1800 commercial frogs per mu, the survival rate of 75% to 90%. The yield per mu is 375 to 450 kg. The average weight is 250 grams, the maximum weight is 350 grams, the harvest of polyculture fingerlings is about 150 kg, the harvest of rice fields is about 550 kg, and the output value per mu can reach about 08,000 to 10,000 yuan (calculated according to the market price in 1992).
The area of rice fields in our country is hundreds of millions of hectares, and there are many rice fields that can breed bullfrogs. The rice paddies have high water temperatures, high oxygen content, suitable pH, rice shade, and abundant bait for bullfrogs to feed. In the polyculture production model of frogs and fish, chemical fertilizers and pesticides are also omitted, and higher yields are obtained. Therefore, the development of rice field breeding bullfrogs is a good thing to do more in one fell swoop.
<h1 class = "pgc-h-arrow-right" > (ix) disease and prevention</h1>
The diseases of bullfrogs and their tadpoles are mainly infectious diseases caused by viruses, bacteria, etc.; there are also parasitic diseases caused by protozoa and crustaceans, as well as some other diseases. The main diseases and their prevention and treatment methods are introduced as follows:
1． Disease control of bullfrogs
(1) Water mold disease.
【Pathogen】 Mainly water mold. One end of the hyphae grows in the host skin tissue, and most of the rest protrudes from the surface.
【Symptoms】 Tadpoles occur mainly because tadpoles are careless in the process of fishing and handling or due to parasite parasites causing skin wounds, and fungal zoospores invade the wound to parasitize. Onset tadpoles swim abnormally, loss of appetite and lead to death.
【Pathogenesis law】 Frog eggs will also be infected by fungi, hyphae invade the egg membrane, eggs or unfertilized eggs injured due to manipulation or other reasons are most susceptible to fungal invasion, once the fungus proliferates on these eggs, it will consume a lot of oxygen to make normal eggs necrotic, and when it is serious, it will cause a large number of frog eggs to mold and die.
【Prevention and control method】 (1) Tadpole pond should be completely cleared with quicklime. (2) The fishing and handling process should be operated carefully. (3) Tadpoles can be soaked with 1/200,000 potassium permanganate solution for 30 minutes.
(2) Anchor head loach disease.
【Symptoms】 It mainly parasitizes the slightly concave part of the junction between the carcass and the tail of the tadpole. The head of the insect body is deeply drilled into the tadpole tissue, leaving the parasitic part of the body to account for 2/3 to 3/5 of the total length of the insect body, sometimes attached to some algae and bell worms, tadpoles are parasitic muscle tissue inflammation and redness, easy to cause other germs to invade, severe ulceration will occur. If there are 3 to 4 carp anchor head bream parasitic on the tadpole body, it can cause death quickly, and when 1 to 2 insect bodies are parasitic, although it will not die immediately, it can make the tadpole grow stagnant and gradually emaciate and die, if the head of the insect penetrates the body wall deep into the body cavity, it will also quickly cause the tadpole to die.
【Control method】 Tadpoles can be soaked with 1/50,000 to 1/100,000 concentration of potassium permanganate solution for 10 to 20 minutes, once a day, 2 to 3 times in a row, if the tadpole appears floating head during immersion, a small amount of oxidized mucus and deposited trace amount of carbon dioxide on the gills should be immediately cleaned with water to ensure that the looming function of the gills is normal.
(3) Red-legged disease.
【Symptoms】 This is the most common and most harmful disease of bullfrogs, which has an acute onset, rapid infection and high mortality. The main symptoms are erythematous or red dot-like skin on the inner side of the legs, and the frog is sluggish and stops eating. The main causes of the disease are frog breeding density, high temperature, poor water quality, and bacterial infection.
【Prevention and control method】 (1) Spray the whole pool with 1×10-6 bleaching powder, once every 10 days, change the pool water once every 7 days, change 1/2 each time, and add oxytetracycline to the bait. (2) Once the disease occurs, it should be isolated in time, and the sick frog should be fished out during treatment and soaked in 10% brine for 5 to 10 minutes, and the sick frog can also be soaked in 100 ml of normal saline containing 400,000 IU penicillin solution for 5 minutes, or soaked with 20% sulfamidine solution for 12 hours.
(4) Gastroenteritis.
【Symptoms】 This is a more serious infectious disease that harms bullfrogs, and its symptoms are: frog body paralysis, weak beating, no water, often drilling into the corner of the pool, etc., stopping eating, generally 7 to 10 days of death. Dissecting the frog body, it was found that there was inflammation and congestion in the gastrointestinal tract, which occurred in spring, summer and autumn. The cause of the disease is that bullfrogs eat rotten and spoiled food.
【Prevention and control method】 (1) Do not feed spoiled food, the bait table should be clean and hygienic, and the remaining residual bait should be removed frequently. Feed fresh bait and sprinkle the whole tank with 1× 10-6 to 2× 10-6 bleaching powder solution every 10 days. (2) For the onset of frogs can be filled with gastric loose tablets or yeast chips, 2 times a day, each time half a tablet, generally 3 to 4 days can be cured. It can also be treated with 0.2 to 0.4 ml of liquid liquid of penicillin 20,000 IU or 0.5 million IU of streptomycin from the mouth. It can also be treated with haloperid acid solution alone, and the effect is better.
(5) Rotten skin disease.
【Symptoms】 The disease is also a common infectious disease that harms bullfrogs more seriously. The causes of the disease are: a single bait, vitamin A deficiency, and a variety of hemolytic pathogens. At the onset of the disease, the skin on the back loses its luster and turns black, followed by the shedding of the epidermis, and decay appears, exposing the dorsal muscles and stopping eating. This disease not only endangers various organs and tissues of bullfrogs, but also the toxic substances secreted by pathogens also seriously endanger the life safety of bullfrogs, and the infection is extremely fast, and most frogs in the pool can be sick at the same time for about 7 to 10 days, and the mortality rate is high.
【Prevention and control methods】 (1) Feed diversification, avoid single, every 4 to 5 days at least once fed animal offal, such as pig and beef liver, every 7 to 10 days with 1 × 10-6 ~ 2 × 10-6 bleach powder sprinkled once in the whole pool. Change the water once every 10 days, 1/3 of each time. (2) The sick frog is picked up and artificially fed with animal offal with high vitamin A mixed with sulfa anti-inflammatory tablet powder, plus 1 cod liver oil pill, which can be cured in 3 to 4 days. Sick frogs can also be soaked in 5% to 10% salt water for 5 minutes, or soaked in normal saline containing 400,000 IU penicillin for 5 minutes, the effect is faster.
(6) Bubble disease.
【Symptoms】 This disease is mainly prone to tadpole appearance, the cause of its occurrence is the deterioration of water quality, a large number of organic matter fermentation to produce small bubbles are eaten by tadpoles, so that the tadpole intestines are filled with bubbles, the abdomen is inflated, swimming on the water surface and dying.
【Prevention and control methods】 (1) Preventive measures are to keep the water quality clean and fresh, and prevent the water quality from being too fat. (2) Immediately replace with new water, inject water once every 2 days during the high temperature period, and replace 1/3 to 2/3 of the pool water each time. Sprinkle the whole tank with 3× 10-6 to 5× 10-6 saline solution, and stop eating for 2 to 3 days, and then feed food after 3 days.
(7) Hemorrhagic disease.
【Symptoms】 This disease mostly occurs in the bullfrog tadpole that will grow on the forelimbs, and its pathogenesis is mainly caused by poor water quality and bacterial infection. Symptoms are redness around the anus, bleeding spots on the abdomen or tail, rapid infection, and high mortality.
【Prevention and control methods】 (1) Preventive measures are to frequently add new water to reduce the density. (2) Soak 1.2 million IU penicillin and 1 million IU streptomycin solution for 30 minutes per 10,000 tadpoles, and the effect is remarkable.
(8) Wheelworm disease.
【Symptoms】 Most of the disease occurs in the tadpole stage of bullfrogs, and the main cause of the disease is that when the wheelworm parasitizes on the surface of the tadpole skin, it sucks on skin tissue cells and stimulates its secretion of mucus. With the naked eye, the tail of the tadpole is bluish-gray spots, and when parasitic on the gills of the tadpole, it will cause the gills to rot, affect breathing, and lead to death.
【Prevention and control method】 (1) The preventive measure is to add new water and reduce the density. (2) With copper sulfate and ferrous sulfate containing agent (5:2) sprinkled in the whole tank, so that the concentration of the pool water reaches 1.4× 10-6 ~ 1.5× 10-6. (9) Curved body disease.
【Symptoms】 The body of the diseased tadpole has an S-shaped bend. The disease may be caused by the soluble water of heavy metal salts in the soil of the feeding pond, the stimulation of tadpole nerve and muscle contractions, or the lack of nutrients such as calcium and vitamins resulting in malformations.
【Prevention and control method】 There are ponds with diseased tadpoles, which can be changed to improve water quality, and usually feed rich in calcium and nutrients.
2． Bullfrog predators and their control
(1) The main enemy of tadpoles.
1) Ant: Its harm is to adsorb on the tadpole to suck dry tadpole blood, so that the tadpole is dead, there is no effective way to kill the ant to save the tadpole, but as long as the water source is kept clean, there are not many ants.
2) Fish finch (fishing lang): copper-blue wings, long beak, slightly larger than sparrow, often flying to the bait table at dusk to grab bait and prey on tadpoles.
3) Frogs and their tadpoles: In the bullfrog tadpole pond to remove frogs and their tadpoles, especially bullfrog tadpoles individual hours should pay more attention, once found a 7 cm long frog tadpole swallowed 32 newly hatched bullfrog tadpoles at a time. The big bullfrog tadpole also eats the newly hatched or recently hatched calfrog tadpole. Therefore, it is necessary to strictly carry out hierarchical breeding.
(2) Bullfrog predators. Bullfrogs' main predators are rats, snakes, cats, water centipedes, wild fish, etc., and we must pay attention to prevention.
<h1 class= "pgc-h-arrow-right" > (ten) compound feed</h1>
1． Feeding habitation of bullfrogs
The success or failure of bullfrog farming mainly depends on whether the bait can be solved well. Bullfrogs feed on live bait, such as only seed breeding, you can use light to lure insects, cultivate maggots, earthworms or catch small trash fish to solve the broodstock bait, if you want to carry out a large number of commercial farming, these alone are in short supply. To this end, in order for bullfrogs to change their feeding habits, from eating live bait to eating dead bait or artificial compound feed, it is necessary to domesticate the feeding habits of bullfrogs.
(1) Materials and methods of domestication. The juvenile frogs are about 15 to 20 grams, and the domestication pond is better than the cement pond, the area is generally 3 to 5 square meters, and 50 to 200 young frogs are stocked per square meter. The depth of the water in the domestication pond is about 10 cm, and the hind legs of the juvenile frog cannot be touched to the bottom. In the middle of the pool is a bait table, which is a wooden square frame, and the sieve silk is tightly packed into a bottom. When the water is deep, the bait table floats on the surface of the water, and when the water is shallow, it falls in the solid place, and there should be no gap at the bottom of the frame to avoid the young frogs from suffocating at the bottom of the frame, except for the bait table, there should be no land or suspended solids in the pool for the young frogs to rest.
(2) Bullfrog feeding domestication and lure substances. Bullfrogs like to eat live bait, and under natural conditions, bullfrogs often hide in the grass, foraging for insects or other small animals that can fly, jump, and crawl. However, their dietary restrictions are not very strict and not immutable. Under the inducement of certain conditions, it can change its feeding habit in a relatively short period of time through domestication.
The feeding domestication of bullfrogs requires an attractive substance, and there are currently the following types of lure substances and domestication methods that can be selected:
1) Live small trash fish. Select small trash fish or household fish fry of the right size into the bait table, the sieve silk cloth at the bottom of the bait table is soaked in a little water, and the depth of the water is so that even if the small fish will not die quickly, it cannot swim freely, and can only lie down and jump. Due to the beating of the small fish, the young frogs are quickly lured to the bait table to feed. After 1 to 2 days of feeding, the larger trash fish (such as crucian carp, wheat ear fish, etc.) can be cut into long strips, and the long strips of small trash fish can also be cut from the middle and mixed with live fish to feed, and then the live fish are gradually reduced, and the proportion of dead fish is increased, so that all the dead fish are fed to the dead fish, or when the dead fish account for the vast majority, the long strip of pellet feed is gradually added, and finally all the granular feed is thrown.
2) Fly maggots. Place the maggots in the bait table, the bottom of the bait table is slightly moist and not soaked in water. The squirming of fly maggots can lure young frogs to feed, although the fly maggots are not as fast as the jumping small trash fish, but they are more palatable than small trash fish, and the mobility is weaker, easy to prey, and most suitable for raising newly metamorphosed young frogs. During domestication, there is no need to add dead maggots to live maggots, because in the intense feeding activities, many maggots are trampled to death by young frogs, so each time they are eaten by dead maggots and live maggots. After 5 to 7 days of feeding maggots, maggots can be mixed with pellets of the right size, and then gradually transition to full pellet feed.
3) Pellet feed. Bullfrog domestication can also be used without live animals as a lure substance, directly fed with pellet feed, pellet feed is best floating, should be the right size. When domesticating with floating feed, the domestication pond water can be reduced to the shallow bottom of the pool just exposed to the surface of the water without using the bait table, and the hind legs of the young frogs in the depths can still not reach the bottom, the young frogs rest in the shallow water, scatter the particles in the shallow water, due to the activity of the frogs, so that the particles slowly drift with the water waves, luring the young frogs to feed. If domesticated with soft pellet feed, a bait table is required, and the pellets are slowly thrown into the sieve silk cloth of the bait table, and the particles bounce up and fall, and the frogs can also be lured to feed. This method of baiting is slower and more time-consuming.
4) Mutual seduction. After feeding on pellet feed for a period of time, the frogs with larger individuals in the domestication pond can be moved to other ponds for breeding, leaving the young frogs with smaller individuals and have become accustomed to eating pellet feed, and then the unacclimated young frogs can be placed in the domestication pond. When feeding pellets, the feeding of domesticated young frogs can stimulate and drive the feeding of unacidional frogs. It is best not to leave a domesticated juvenile at a time less than 1/5 of the unacqualiated frog.
2． Early breeding of juvenile frogs for domestication
Due to the relationship between tadpole breeding, the newly metamorphosed young frogs vary greatly, from only 3 to 5 grams of small to more than 20 grams of large ones. It has been observed that young frogs over 20 grams can feed on frogs under 15 grams. Therefore, frogs with individuals under 15 grams are generally not suitable for feeding domestication with frogs with larger individuals, and should be separated. Breeding is carried out for a period of time with suitable live bait before domestication, which is called pre-domestication breeding.
If conditions permit, it is best for newly metamorphosed young frogs to undergo a period of pre-cultivation, because:
(1) Tadpoles basically do not eat foreign bait during the metamorphosis period, and completely rely on absorbing the nutrients of their own tails to supplement the consumption in the body, so after metamorphosis, there is no nutrient accumulation in the body, and the physique is weak at this time. The pre-cultivation is mainly to allow them to obtain a certain amount of bait evenly, make them strong and have a certain amount of nutrient accumulation before domestication.
(2) Just-metamorphosed young frogs are bullfrogs from aquatic to terrestrial transition period, their morphological structure, habits and feeding habits are changing, various organs are not very perfect and developed, jumping predation ability is also poor, early cultivation is to use their nature to prey on live bait, with a palatable and easy to catch live bait feeding, so that it can adapt as soon as possible. It is different from the tadpole's feeding method and exercise of predatory ability.
(3) If food domestication is not carried out directly without pre-breeding, there is no guarantee that each frog will receive enough food at the beginning of domestication. In particular, smaller frogs, if there is no certain amount of nutrient accumulation in advance, are originally thin and cannot get nutritional supplements in time, they will gradually die, or form polarization, and the phenomenon of large food and small food will occur. Bullfrog in the tadpole growth of forelimbs into a juvenile landing stage is the most likely to die period, at this time the selection of suitable bait, careful breeding, pre-cultivation, is to reduce the death of this stage, improve the survival rate of the key measures. The bait for early cultivation is best for maggots, which are of a palatable size, poor mobility, and easy to prey, followed by small trash fish, and small trash fish or fry with a body height of less than 0.5 cm can be selected.
3． Considerations for domestication
Although bullfrogs eat live bait, it is inherent in the life habits of frogs, but it is completely possible to change this habit, but it is more difficult. This requires not only certain conditions and methods, but also patience and perseverance. Even if the use of domestication methods temporarily changes their habits, it is even more difficult to make it completely stable. Because their inherent nature still exists, it cannot disappear from one generation or two generations or generations. And it's much easier to restore their nature than to change it. Therefore, the following should be noted when domesticating bullfrogs:
(1) Domesticated young frogs should be divided in size to prevent large frogs from eating small frogs.
(2) The domestication pool should not be too large, 3 to 5 square meters of cement pool, the bottom of the pool has a certain slope, there is no concealment.
(3) Stocking should have a certain density, at least not less than 50 per square meter, up to 400 to 500, the number of excessive feeding is uneven, and it is easy to polarize.
(4) Domestication must be on time, generally 2 times a day, after forming a habit, the time the young frog will automatically concentrate on the bait table.
(5) Bullfrog excrement is easy to spoil and stink, frog pond should change the water once a day to ensure that the water quality is fresh and prevent diseases.
(6) The memory of young frogs for domestication is not very strong, eating dead bait is only a conditioned reflex, and the nature of feeding live bait still exists, so after domestication, it should insist on feeding dead bait or pellet feed.
4． Artificial compound feed for bullfrog tadpoles
(1) The feeding habits of bullfrog tadpoles. The diet is staged, with tadpoles feeding on plankton and organic detritus during their growth, while juvenile and adult frogs feed on live fish, shrimp, earthworms and insects. China's artificial breeding of bullfrogs in the efforts of farmers has gradually changed the diet, for a long time, in the tadpole growth period is mainly fed soy milk or cooked egg yolk, 1 month old tadpoles with plant feed such as corn flour, bean flour, bran and animal feed such as fish meal, bone meal, silkworm pupae and other feed mixed with the feed made of feed, it is very easy to pollute and cause waste. The growth period of young and adult frogs is dominated by feeding maggots, earthworms or bread worms, which rely on artificial rearing and are labor-intensive. Some farms after a long period of artificial domestication, bullfrogs can already eat dead things, they will be small trash fish, shrimp, pigs, cattle lungs cut or mixed with plant powder feed and fishmeal into a ball in the food bowl to feed bullfrogs, but due to the deterioration of the remaining feed and water pollution reduced the survival rate of bullfrogs.
Bullfrog visual physiology is very special, can clearly see the material in a certain range of activities, but can not see the static things, therefore, in the process of artificial breeding of bullfrogs, the source of its feed and feeding methods have been greatly limited, so far, China's bullfrog breeding is still stuck in small professional households, farmers and experimental field production, the area is generally below 100 acres, and has not formed a large-scale production. At the same time, due to the fact that there are more animal feed bacteria eaten by bullfrogs at present, live bullfrogs have been detected to have a large number of parasites in the body during customs immune inspection, and the export of live frogs has been cut off, so it is urgent to study artificial feed to meet the needs of bullfrog breeding.
(2) Research on artificial compound feed for bullfrogs. Taiwan Province, Cuba, the United States and other countries in China use artificial compound feed in large-scale bullfrog farms, and the feed is generally puffed floating pellet feed or soft pellet feed. The expanded pellet feed formula of bullfrog in Taiwan Province is relatively advanced, and it is divided into three different growth stages of nutrient formula of tadpole, young frog and adult frog, and the granular floating. China's mainland research in this area is still just starting, the domestic specialized production of bullfrog artificial compound feed factories are still very few, therefore, the development of domestic bullfrog artificial compound feed and its processing machinery, will have a positive impact on the further development of bullfrog breeding industry. Feeding bullfrogs with artificial pelleted feed can help bullfrogs digest and absorb, accelerate growth, shorten the breeding cycle, prevent and control frog diseases, and reduce labor intensity. At present, China has adopted foreign advanced feed formulas, using freshwater fish puffed granular feed processing technology and shrimp pellet feed processing technology, initially developed a suitable for China's national conditions with floating and sedimentation in the softening of two kinds of pellet feed, the main features are as follows:
1) The feed imitation insects are strip-shaped, which can be fed from the tadpole stage of bullfrogs, and gradually domesticate the feeding habits of bullfrogs.
2) Feed floating cookability. For floating granular feed, due to the maturity of the starch, easy for bullfrogs to digest and absorb, the feed floats on the surface of the water, bullfrogs will mistakenly think that insects swim on the surface of the water, as long as a bullfrog jumps up and swallows will drive other bullfrogs to compete for food, the effect is very good.
3) Reduce water pollution. The remaining feed should be fished out in time to avoid polluting the water body.
4) The feed should contain the nutrients necessary for the growth of bullfrogs to shorten the breeding cycle and accelerate the growth rate.
5) Can prevent and treat diseases. Adult frogs are not easy to get sick, but in the tadpole metamorphosis stage, the young frog period is very susceptible to infection, survival rate is low, due to the adsorption of pellet feed, before feeding the liquid sprayed into the feed than the liquid directly sprinkled into the breeding pond, the control effect is more significant.
6) Artificial compound feed can reduce labor intensity, with the advantages of easy storage and no pollution.
5． A typical introduction to the development of artificial compound feed for bullfrog tadpoles
In recent years, the bullfrog breeding industry has developed rapidly, and there have been many studies on the feed of bullfrog farming at home and abroad, but the emphasis is on natural food. In 1986 and 1987, the Fujian Fisheries Institute used different formulas of feed to carry out breeding experiments on bullfrog tadpoles in order to find out the best feed for breeding bullfrog tadpoles, cultivate young frogs with early metamorphosis and individual size, and lay a good foundation for high-yield breeding of adult frogs. The results of the test are as follows:
(1) Method.
Raw materials for the formula: The animal protein in the raw materials of the experimental formula is mainly fish meal and blood meal, and the plant protein is mainly made of peanut cake, bran, rice bran, wheat flour, etc., and a small amount of minerals and vitamins are also added.
Methods: The experiment was carried out in a cement pond of 5 square meters, and the stocking density was 100 individuals per square meter, that is, 500 small tadpoles were stocked per pond.
The test used small tadpoles hatched 13 days after the bullfrog tadpole line had an average body length of 2.78 cm and an average weight of 0.34 g, and also used small tadpoles after incubation for 5 days, with an average body length of 1.4 cm and an average weight of 0.1 g.
The experiment used different formulas to observe the breeding effect of tadpoles, and then selected the formula with better effect for repeated tests, and the water level of the test pool was maintained at about 50 cm. In summer, when the water temperature is high, the water level can be appropriately deepened and the floating lotus can be thrown to avoid excessive temperature. Bait at about 4% of body weight, twice a day.
(2) The main nutrients of the formula. The main nutrients of the four formulated feeds of 86-1, 86-2, 86-3 and 86-4 are shown in Table 6.
Table 6 Main nutrient components of feed (%)
The feed price of the four formulas is: 86-1 formula is 0.68 yuan / kg, 86-2 is 0.78 yuan / kg, 86-3 is 1.22 yuan / kg, 86-4 is 0.68 yuan / kg. Using the 86-3 formula to calculate the bait coefficient, raising 100 tadpoles to metamorphosis requires a feed fee of 1.73 yuan.
(3) Test effect. The four formulations were repeatedly tested in 1986 and 1987 and the growth rates of tadpoles fed on different formulation feeds were compared (Table 7). It can be seen from Table 7 that the 86-1 and 86-3 compound feeds are significantly better than 86-2 and 86-4 in terms of tadpole body length and weight growth. 86-4 as a control group, the raw material does not contain animal protein.
Table 7 Comparison of tadpoles growth rates of different formulations
Different formulations of feed also have a certain impact on the metamorphosis and survival rate of tadpoles. In the second batch of trials in 1986, the metamorphosis rates of 86-4, 86-2 and 86-3 were 92.5%, 92.1% and 97.6%, respectively.
The average weight of the metamorphosed froglets in the 86-3 formula is 9 grams, which is only 4 grams heavier than the average weight (5 g/piece) of the metamorphosed frogs in the 86-4 formula.
(4) Granulation requirements for bullfrog artificial compound feed. (1) The protein content in the bullfrog compound feed formula is required to be more than 40%. (2) Puffed granules are required to be able to disperse on the surface of the water for 6 hours, and the sedimentary granular feed must be softened to adapt to the swallowing ability of bullfrogs. (3) The minimum diameter of the feed particles in the tadpole stage is less than 1.5 mm, the length is greater than 4 mm, and the diameter of the frog feed is 6 to 8 mm, the length is 30 mm, and the sedimentary feed can be slightly larger.
(5) Feed processing process and requirements.
1) Processing process.
Raw powder → screening → ingredients→ stirring→ conveying → granulation
2) Floating granulation requirements. The ingredients are fully mixed, the starch content is evenly distributed, and can pass the 1.0 mm granulation die, requiring raw materials to be ultra-finely crushed, and then screened by more than 80 mesh, processing more than 2.5 mm particles do not have to go through ultra-fine crushing, and the temperature in the puffing unit cannot be too high, so as not to coking the raw materials. However, it must be ensured that the raw material is completely heated to form a paste-like film-inclusive feed to ensure its floatability in the water.
3) Depository granulation requirements. Sedimentary pelleted feed is a medium soft pellet feed between soft and hard pellet feeds, which is tempered by steam and sprayed with grease, nutrient solution or other trace elements before packaging to the extent that bullfrogs can swallow.
6． Bullfrog feeding pellet feed precautions
(1) Pay attention to the use during the storage period when feeding, and do not feed spoiled and moldy granular feed.
(2) When first used, a water spray device should be set up at the edge of the frog pond to increase the dynamic of the feed in the water, enhance the feeding rate of bullfrogs, and feed from a small amount to normal feeding.
(3) The amount of feeding should be 0.5 to 1 hour after feeding. If the overfeeding will not only cause waste of feed and pollute the water quality, but also lead to the proliferation of germs. The general feeding volume is controlled at 3% to 5% of its body weight. Under normal circumstances, if the phenomenon of bullfrog excreting feces floating on the surface of the water, the amount of feeding should be reduced to make the defecation normal.
(4) Attention should be paid to the selection of pellet feed with different particle sizes at different stages and different specifications.
(5) In the juvenile frog stage, attention should be paid to the appropriate addition of vitamin A, so as to avoid the occurrence of rotten skin disease.
(6) Pay attention to the water quality of the frog pond, rinse the excrement of the bullfrog at the bottom of the pond in time and remove the remaining bait to prevent disease due to water pollution.
< h1 class = "pgc-h-arrow-right" > (xi) a test of raising bullfrogs with pig lungs</h1>
(1) Characteristics of pig lung rearing bullfrogs. First, the operation is simple, using the characteristics that pig lungs can float on the water, due to fluctuations caused by wind or frog activity, so that bullfrogs are mistaken for live bait and eat. Second, pig lung has a wide source, low price, and is not affected by seasonality. Third, in places where conditions permit, pig lungs can be used as feed, and large-scale breeding can be carried out, with small investment and large returns.
(2) Processing and feeding of pig lungs. Take fresh pig lungs, remove the trachea and fat attached to the pig lungs, now use the current processing, the size of the processing depends on the size of the bullfrog, generally 2 to 8 mm square, processing can be used to grind meat or with a knife to cut fine, if it is frozen pig lungs, should first put into warm water and press the heavy object to make it all immersed in water for about 1 hour before processing.
When feeding the processed pig lungs to bullfrogs, they should be fed regularly, quantitatively, and at fixed points, generally in the morning or dusk every day, fed twice a day, and the amount of each feeding should be completed within 40 minutes after feeding.
(3) Pig lung frog raising effect.
1) Frog stage: stocking 50 kg of young frogs, the average weight is 25 grams, the daily feeding of pig lungs is 2.5 kg, after about 130 days of feeding, harvest bullfrogs 250 kg, the average frog weight is 150 g, the largest individual can reach 240 g. A total of 325 kg of pig lungs were fed, the feed coefficient was 1.6, and the feed cost per kg of frogs was 1.28 yuan.
2) Adult frog stage: stocking 50 kg of frog species with a weight of 150 g, the average daily feeding of pig lungs is 2.8 kg, after 180 days of feeding, adult frogs can be harvested 350 kg, the average weight is more than 500 grams, the largest individual can reach more than 700 grams, a total of 504 kg of pig lung feeding, feed coefficient of 1.68, per kg of frog feed cost of 1.34 yuan.
(4) Pig lung frogs should pay attention to. (1) Keep the water fresh; (2) pay attention to the freshness of the pig lung, can not feed the deteriorated or smelly pig lung; (3) when feeding, set up a feed table to prevent the pig lung from floating around. For the remaining feed, it should be fished out in time to avoid spoilage.
<h1 class="pgc-h-arrow-right" > (xii) harvesting and processing</h1>
1． Bullfrog harvesting
Bullfrogs after about 1 year of rearing, can be harvested and sold or processed, the individual reached 0.3 to 0.5 kg as a commercial frog is appropriate, in Beijing, Kunming, Guangzhou, Shanghai major hotels, restaurants sold commercial frogs weigh 300 ~ 500 grams.
(1) Harvesting method. Bullfrog harvesting is generally carried out by manual capture, which includes:
1) Light capture. At night, the flashlight light is illuminated to the bullfrog's eyes, and the bullfrog is blinded by the strong light, and it does not move for a while, at this time, it can be caught by net or hand.
2) Bait fishing. Use a bamboo pole with a length of 2 to 3 meters, a transparent nylon thread of about 3 meters long at one end, and a large insect such as earthworms and grasshoppers at the end of the line, and prepare a mesh bag with a handle length of 1 meter at the other end. When catching, the right hand holds a bamboo pole, shaking up and down, the left hand holds the mesh bag, and when the frog swallows the bait rod sinks, it can be collected and the frog is caught into the net bag.
3) Dig up to capture. Bullfrogs in the hibernation period lurk under the permafrost layer to hibernate, 50 to 70 cm from the ground, up to 1 meter deep, with a hoe or shovel to turn over the pond, pond soft soil, can catch bullfrogs.
4) Small net capture. During spawning, bullfrogs hug each other, chase the opposite sex, are insensitive to food, are slow to move, and are easier to catch. At this time, the right bullfrog can be caught with a nylon net with a handle length of 1 to 1.5 meters and a diameter of 50 cm.
The above four harvesting methods are all harvesting methods for large-area natural grazing bullfrogs in the wild. Ponds are stocked, with small areas, can be rounded up in ponds with large nets, and then select moderately sized individuals, put them into bags or boxes, barrels, and then process them.
In addition, if the area of aquaculture in rivers or lakes is large, it can also be caught with steel forks, fish hooks or shots with tiny shotgun shells, but this method makes bullfrogs mostly injured inside and outside, and it is not suitable for long-distance transportation or temporary breeding, and can only be caught and sold or processed. Otherwise, the wound is very susceptible to infection by germs and leads to death.
(2) Harvesting standards. (1) A layer of clean and transparent mucus, bright body color, strong body, no internal and external disability, no flatulence in the abdomen, no disease for the genuine product. (2) Slow movement, abdomen facing upwards in the water, unable to flip over on its own, no keen response to external stimuli, body surface mucus falling off, body color loss, thin body, internal and external disability or disease (such as red legs), abdominal flatulence are defective. It is also a sign that a live bullfrog is about to die. (3) Dead bullfrogs with stiff bodies and odors are spoiled.
The quality of bullfrogs is good or bad, which directly affects its taste and nutritional value. Whether the commercial sector operates bullfrog products or consumers buy bullfrogs, they should know the quality of bullfrogs.
2． Processing of bullfrogs
Harvested bullfrogs can be processed directly for consumption, frozen and further processed.
(1) Edible processing. The harvested bullfrog is first washed with soil, then the live bullfrog is held in hand, the head is facing down, the head is cut off with a kitchen knife, the skin is peeled, and then the abdomen is cut open to remove the internal organs, washed with water, and then cooked.
In summer and autumn, after wetting the bullfrogs with water, put them into a special bullfrog cage, and then put the cage in the water in the basin, the water is deep enough to the bullfrog belly, and when the weather is hot, it is necessary to often pour water. In winter and spring, bullfrogs can be put into the pool, or sealed with a sack cover to keep warm, rinsed with water once a day, temporarily raising bullfrogs in the pool, can not be mixed with soot and grease, otherwise it is easy to cause bullfrog death. Temporarily raised bullfrogs can be removed from cages or ponds for processing at any time.
If you buy frozen bullfrog meat, you can put it in cold water at about 15 ° C to thaw naturally. After thawing, drain the water and use gauze to absorb the remaining water, which can be processed and cooked.
(2) Frozen processing. The weight size (different standards required by various countries) is graded into a plastic bag or box, put into a freezer below -25 ° C, quickly frozen, and then put into cool water to rinse it, so that the plastic bag is wrapped in a layer of ice coating, the bullfrog body is isolated from the air, and then sent to the low temperature warehouse of about -1 ~ 8 ° C for storage, ready for export or supply to the market. It is advisable to store for no more than 6 to 7 months. In the international market, the price of frozen bullfrog meat in 1985 was more than $10,000, and every 2.5 tons of fresh bullfrogs can be processed into 1 ton of frozen bullfrog meat.
(3) Deep processing. The internal organs of bullfrogs and other scraps are managed and biochemically processed deeply, which can produce peptones, various amino acids, enzymes and hormone preparations, thereby improving the economic value of bullfrogs.
(4) Processing of canned stewed bullfrogs.
1) Selection and treatment of raw materials.
A． bullfrog. Each weighs about 0.4 kg, decapitate and peel, remove the claws, remove the internal organs, wash with water, drain and cut into pieces, cut the limbs first, and then cut the frog body into 3 to 4 cm pieces of frog meat.
B． mushroom. Take fresh, fungus cover buds, about 3 cm in diameter mushrooms, placed in room temperature water for 4 to 5 hours, then fished up and rinsed, drained, poured in boiling water as soon as possible pre-cooked for about 8 minutes, to cook is appropriate, you can add 0.07% citric acid in pre-hot water. Pre-cooked and quickly fed into a cooling tank to cool.
C． Wine. Choose low-grade wines with more than 14.5 °C and storage time of more than 1 year, such as Shaoxing wine.
2) Pre-cooking and canning of bullfrogs. Place the cut frog meat into a stainless steel sandwich pot and let the water flood over the frog meat. When it is cooked until it is three years old, it is fished out and put into a detoxified and cleaned jar together with the pre-cooked mushrooms, and the proportion of frog meat mushrooms canned is 2:5:1, and the solid content in the tank is not less than 60% of the volume of the can, and then the soup juice is added. The preparation of the soup sauce is: 100 kg of soup sauce with salt 2.5 kg, monosodium glutamate 0.25 kg, peanut oil 1.5 kg, onion 0.8 kg, cooking wine appropriate amount, ginger, cinnamon, pepper, etc., add water and mix, boil for about 10 minutes, filter, add hot to the tank.
3) Sealing, sterilization and packaging of canned food. The sealing adopts exhaust gas and vacuum sealing method, and the vacuum degree is above 450 mm Hg. After sealing, it is sterilized at high temperature at a temperature of 118 °C. After the sterilization is over, when the tank is cooled to below 40 ° C, the can is wiped clean, and a few cans are randomly selected and placed in the culture room, and at 27 ° C±1 ° C is a qualified product, labeled, packaged and stored.