Core Tip: In the normal conditions of incubation, the distribution of embryonic death is more regular. From the curves, it can be seen that there are two death peaks. The first time is 3-5 days after hatching. The number of dead embryos accounts for 15% of all dead embryos. The second time is 18-20 days after hatching. 50% of all dead embryos.
Under normal hatching conditions, the distribution of embryonic death is more regular. From the curves, it can be seen that there are two death peaks. The first time is 3-5 days after hatching. The number of dead embryos accounts for 15% of all dead embryos. The second time is 18-20 days after hatching. 50% of all dead embryos.
In high-hatch chickens, the number of chick embryos died at the second peak; in the low-hatching chickens, the two peak mortality rates were similar and the second peak was slightly higher. The first death peak is when embryos grow rapidly and various embryonic membranes form one after the other but are not yet perfect. Embryos are sensitive to changes in the external environment. The second death peak is at the embryo's breathing from the chorioallantoic membrane and transitions to lung respiration. At this time, the physiological changes of the embryos were intense, the oxygen demand increased rapidly, and the temperature increased rapidly. The threat of infectious embryo disease was more prominent, and the requirements for the incubation environment were high. Some weaker embryos could not be shelled and died.
Embryonic death is closely related to vitamin deficiency, thus affecting hatchability, and affecting the quality of chicks and the survival rate of chicks at the early stage of brooding and the development of chicks, which should cause great concern.
When embryos lack vitamin A, the incidence of ectopic embryos increases, and the circulatory system develops abnormally. Embryos may die within the first week of incubation, or may survive until the end of the incubation period but have no ability to hatch, or may die quickly, although they may hatch. If the hen lacks VA, the chicks develop symptoms about 1 week after hatching. It was found that the amount of VA in the liver of young chicks was more than 3 times higher than that of weak chicks.
Inadequate storage of vitamin D in hens leads to retarded growth and osteomalacia in chicks, and manifests pheasants and leg disease during brooding. Usually accompanied by decreased eggshell quality such as changes in eggshell gaps. It was found that the amount of VD in the liver of young chicks was more than 2 times higher than that of weak chicks. Experiments have shown that adding 25-hydroxyvitamin D3 to breeders can promote embryonic development and increase hatching rate; effective prevention of pheasants during brooding can reduce chick mortality by 1-3%.
The lack of VE, 1-3 days early embryo death, showing brain softening and exudative qualities. The chicks need higher VE, which needs to be transferred to the chicks a few days before hatching. It was found that the amount of VE in the liver of the young chicks was more than twice as high as that of the weak chicks. Brooding period should pay attention to supplement VE.
In the absence of vitamin K, the chicks bleed and bleed when they emerge from the shell, and the 1-day-old chicks suffer from excessive bleeding when they die.
In the absence of thiamine (B1), two stages of embryonic death occurred, one early and the other 19-21 days. A large number of chicks died at the time of landing, but there were few deformed chickens. The 10-14-day-old chicken had a higher mortality rate. The chicks soon got better after the injection of thiamine. Some disinfectants, anticoccidial agents, and poor quality fishmeal can exacerbate thiamine deficiency. Recent studies have demonstrated that when certain Fusarium molds are present, the use and destruction of vitamin B1 (thiamine) by molds tends to cause a lack of thiamine, and the need for thiamine increases.
Biotin is necessary to maintain the normal embryonic development and hatching rate. The lack of biotin in the eggs will lead to an increase in the rate of dead embryos in the first and third weeks of incubation. External biotin supplementation can solve the problem of lack of eggs. The lack of biotin mainly reduces the hatching rate, but has little effect on egg production. The embryonic death rate peaks in the first week of incubation and lasts for 3 days. Insufficient or lack of biotin in the diet will lead to an increase of death peaks 5 or 17 days before hatching. Cartilage dystrophy or short limbs, short bones, and parrots, etc., may show skeletal deformities and crooked bends.
There was a lack of riboflavin (B2), and a large number of embryos died at day 9-14 or 17-21. Embryos developed edema and/or sticky villi. Chicks were extremely bent.
Lack or deficiency of folic acid can cause embryonic development malformations and even death. Supplemental folic acid supplementation can increase egg weight and shell weight. At the same time, prolonged shelf life of the egg will result in lack of folic acid in the embryo.
In the absence of vitamin B12, embryonic death occurs approximately 8-14 days, often accompanied by edema, claws, and short beaks.
Pantothenic acid is absent, and unhatched chicks have subcutaneous bleeding.
The breeder has sufficient vitamins. Under hatching conditions, the hatching rate of the hatching eggs can reach as high as 87%. The hatching rate of the fertilized eggs can reach as high as 92%, the hatching rate can reach as high as 98%, and the finish-free hatching can not exceed 4-5%. The dead embryos were less than 2%, the dead embryos were less than 2-3%, and the dead embryos were less than 6-7% after transfer.
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