In the production of layer chickens, the level of egg damage directly affects the economic benefits of raising chickens. Under normal circumstances, the egg damage rate - generally between 1-3%, and some chicken farms damage rate is too high, even up to about 6% or more, especially in the first chicken performance is more serious, which is bound to cause great losses to production. Therefore, it is of great significance to find out the causes and preventive measures of high damage rate to improve the efficiency of chicken raising.
In order to better analyze the causes of broken eggs, first understand the formation process of eggs, mature follicles enter the fallopian tubes, and the protein secreted by the fallopian tubes envelops the yolk, and then gradually descends, forming the inner outer membrane, and finally reaching the uterus, which is where the eggshell is formed. The basic component of the eggshell is CaC03, the content is about 95-98%, the rest is protein, the uterus uses its own metabolism to produce CO2 in carbonic anhydrase action to combine with water to H2CO3, H2CO3 dissociates to produce CO32-, CO32- and then combines with Ca in the blood to form CaC03, CaCO3 is uniformly deposited on the eggshell membrane to form a hard eggshell. Therefore, any factor that causes insufficient calcium source in chickens can make the eggshell quality worse and break the eggs more.
First, the formation of broken eggs: the main factors affecting the quality of the first egg shell are related to the nutrition, disease, environmental temperature, management, etc. of the chicken, and the following is a brief analysis of various factors.
1, nutrition: reasonable and adequate nutrition is to ensure the normal growth and production of chickens, must make the proportion of protein, energy, minerals, vitamins and other proportions in the feed reasonable and sufficient. For laying hens, due to the need to form eggshells, there are special requirements for nutrition, and several major elements that affect the quality of eggshells are calcium, phosphorus, sodium, chlorine, magnesium, manganese, VD3 and so on. Calcium carbonate is the main component of eggshell, must ensure that there is sufficient and appropriate proportion of calcium, phosphorus in the feed, in general, the calcium content in the feed of laying hens is about 3-5%, the available phosphorus content is 0.6%, the content is insufficient or the proportion is out of proportion, it will affect the quality of the eggshell, so that the damage of the egg is increased. If the available phosphorus content in the diet exceeds the physiological requirement (about 0.45%-0.55%), it interferes with calcium entering the bloodstream from the bones when the eggshell is formed, and below the physiological requirement will also lead to fatigue in caged chickens. The VD3 plays an important role in promoting the absorption of calcium and phosphorus, and the lack of VD3 is not conducive to the absorption of calcium and phosphorus and the formation of eggshells, which increases the damage of eggshells. Na+ and CI- in the diet affect the level of phosphorus in the blood, and only when Na+ and CI- act on phosphorus can the effect of excess phosphorus be counteracted and the proportion of calcium and phosphorus is appropriate. Due to the interaction between manganese and calcium, phosphorus and magnesium, manganese plays an important role in improving the quality of eggshells, and the appropriate content of manganese in the feed is 75 mg/kg and the content of magnesium is 0.04%.
2, many diseases such as Newcastle disease, infectious bronchitis, avian influenza, infectious laryngeal tracheitis, egg reduction syndrome, rhinitis, etc. can affect the quality of eggshells, these diseases on the one hand cause chickens to eat decreased, so that calcium and phosphorus intake is insufficient, on the other hand, the reproductive system of chickens is more serious damage, so that the fallopian tubes are inflamed, promote the formation of eggshell glands Secretion decreased, interfere with the ability to form eggshells. There is also aflatoxin, if the feed is contaminated with mycotoxins, long-term feeding can reduce the quality of eggs and increase the number of broken eggs. The heavy use of sulfonamides, furans and other drugs can also affect the quality of eggshells. In addition, some chickens suffer from egg eating habits and eating eggs is also a reason for egg damage.
3, the ambient temperature of the egg-laying hen the best ambient temperature to 15-21C is appropriate, the higher the coop temperature exceeds the temperature, the greater the damage rate of the egg, this is because due to the high temperature heat stress on the one hand, the chicken feed intake is reduced, the intake of calcium and phosphorus is reduced, on the other hand, the high temperature makes the chicken's respiratory rate increase The exhaled CO2 increases, thus reducing the CaCO3 deposition in the body, which in turn affects the eggshell quality. Tests have proved that when the temperature of the chicken coop exceeds 32C, the damage rate is significantly improved.
4. Management and age factors: There are many factors in management, including the age of the date of birth, weight, density, light time, egg picking time, frequency, etc. There is evidence that excessive density and long light time will make chickens irritable and frequent, and the calcification process affecting the eggshell will increase damage. Low birth weight (1500 grams below the standard weight) reduces egg laying rates and eggshell quality because chickens have to maintain their own development and bear the burden of egg laying. The number of eggs picked up and the time of the difference also have a great impact on the damage. There is also the damage of the cage, the working attitude of the egg pickers, etc., which have a certain impact on the damage of the eggs.