In the production of layer chickens, the damage rate of eggs directly affects the economic benefits of chickens. In general, the damage rate of eggs is generally between 1-3%, and in some chicken farms, the damage rate is too high, even more than 6%, especially the newly hatched chickens, 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 hazard rate to improve the breeding efficiency of chickens.
In order to better analyze the cause of egg damage, first understand the egg formation process, mature follicles enter the fallopian tubes, the fallopian tubes secrete proteins surround the yolk, and then gradually descend to form the inner outer membrane, and finally reach the uterus, which is where the egg shell is formed. The basic component of the eggshell is CaC03, which is about 95-98%. The rest is protein. The uterus, under the action of carbonic anhydrase, uses the carbon dioxide produced by its metabolism to generate H2CO3. H2CO3 breaks down and produces CO32-, which then binds to calcium in the blood to form CaC03. Calcium carbonate is evenly deposited on the eggshell membrane, forming a hard eggshell. Therefore, any factor that causes the lack of calcium sources in the chicken body will make the eggshell quality worse and the number of damaged eggs increases.
One. Causes of damaged eggs: The main factors affecting the quality of the first layer of eggshells are related to the nutrition, disease, ambient temperature and management of chickens. The following is a brief analysis of the various factors.
One. Nutrition: Reasonable and adequate nutrition is the basis for ensuring the normal growth and production of chicken, and the proportion of protein, energy, minerals and vitamins in the feed must be reasonable and sufficient. But for layer chickens, due to the need for eggshell formation, there are special requirements for nutrition. The main elements affecting the quality of eggshells are calcium, phosphorus, sodium, chlorine, magnesium, manganese, VD3, etc., of which calcium carbonate is the main component of eggshells. It must be ensured that the proportion of calcium and phosphorus in the feed is sufficient and appropriate. In general, the calcium content in the feed of layer chickens is about 3-5%, and the available phosphorus content is 0.6%. If the content is insufficient or out of proportion, it will affect the quality of the eggshell and increase the damage to the egg. If the available phosphorus content in the diet exceeds the physiological requirement (about 0.45%-0.55%), the formation of eggshells will interfere with the entry of calcium into the bones into the bloodstream, and below the physiological requirements will also cause fatigue in caged chickens. VD3 plays an important role in promoting calcium and phosphorus absorption The lack of VD3 is not conducive to the absorption of calcium and phosphorus and the formation of eggshells, resulting in worsening eggshell damage. Only when sodium and cerium play a role in phosphorus can the effects of excessive phosphorus be counteracted, making the calcium-phosphorus ratio appropriate. Due to the interaction of manganese with calcium, phosphorus and magnesium, manganese plays an important role in improving the quality of eggshells. The suitable content of manganese in the feed is 75 mg/kg and the suitable content of magnesium is 0.04%.
2。 Many diseases, such as Newcastle disease, infectious bronchitis, avian influenza, infectious laryngopheitis, egg fall syndrome, rhinitis, etc., can affect the quality of eggshells. These diseases lead to a decrease in the intake of chickens, insufficient intake of calcium and phosphorus on the one hand, and on the other hand, serious damage to the reproductive system of chickens, inflammation of the fallopian tubes, decreased glandular secretion, interference in eggshell formation and the ability to form eggshells. If the feed is contaminated with mycotoxins, long-term feeding can reduce the quality of the eggs and increase the number of broken eggs. A large number of sulfonamides, furans and other drugs can also affect the quality of eggshells. In addition, some chickens suffer from egg eating disorder, which is also one of the reasons for the broken eggs.
Three. The optimal ambient temperature for egg-laying hens is 15-21 ° C, and the higher the temperature, the greater the damage rate of eggs. This is because on the one hand, the intake of calcium and phosphorus will be reduced, and on the other hand, the high temperature will increase the respiratory rate and exhaled carbon dioxide, thereby reducing the deposition of calcium carbonate and affecting the quality of the eggshell. The results show that when the temperature of the chicken coop exceeds 32 °C, the hazard rate of the chicken coop increases significantly.
Four. Management and age factors: There are many factors in management, including age, weight, density, light time, egg collection time, frequency, etc. There is evidence that excessive density and long light time will make chickens irritable, frequent activities, affect the eggshell calcification process, and increase damage. Low birth weight reduces egg laying rates and eggshell quality because chickens must maintain their own development and bear the burden of egg laying. The number and timing of egg harvesting also have a great influence on pests. The damage of the cage and the working attitude of the egg picker have a certain impact on the damage to the eggs.