The main reason for poor eggshell quality of laying hens after 400 days of age
Laying hens are 400 days old, which is the later stage of rearing, and are commonly called "old chickens". At this time, the quality of eggshells generally began to decline, the thickness and strength of the eggshells decreased, the white shells, soft shells, sand shells, thin shells, and cracked eggs increased, and the damage rate increased.
The main problem is that the physiological reproductive function of "old chickens" is reduced and the reproductive organs are aging. If precise nutrition adjustment can be carried out, the physiological function can be improved, the quality of eggshells can be improved, the rate of decline of egg production can be delayed, and the egg production performance can be fully exerted.
1. In the later stage, the eggs are large, the need for calcium increases, and the proportion of eggshells in the egg becomes smaller. With the increase of the age of the laying hens and the aging of the reproductive organs, the overdraft of nutrients is caused by egg production, and the consumption of calcium and phosphorus in the body is accelerated. The shell is relatively thin;
2. Usually due to the lack of calcium and vitamin D, and calcium exists as a stable substance, vitamin D is easily destroyed by oxidation;
3. Chicken liver cannot store proper amount of vitamin D, only a small amount of vitamin D;
4. The intestinal absorption function of old chickens is weakened, and they are often diarrhea, and the absorption capacity is worse, resulting in a decrease in protein absorption and utilization.
5. The reproductive function of old chickens is reduced, the secretion of estrogen is reduced, and the function of promoting the 25-hydroxylation of vitamin D3 and protecting vitamin D3 and 25-hydroxy vitamin D3 from enzymatic degradation is weak;
6. Thin eggshells, low hardness, brittleness, and increased damage rate. The reason is that the supply of calcium is insufficient. Under normal circumstances, it is not the lack of calcium in the feed, but the body lacks the substance vitamin D3, which is 25-hydroxyl. Vitamin D3;
7. Fatty liver of laying hens is very common in the late feeding period, the liver is damaged, the function is weakened, and the metabolic transformation ability is reduced;
8. Old chicken body fat is easy to deposit, because the body fat deposits certain fat in the uterine glands, which in turn affects the secretion function of the glands, reduces the secretion of calcium, and the eggshell becomes thin and brittle;
9. Decay of kidney function,and common kidney swelling, affecting the final conversion of D3;
10. Decreased liver function, especially long-term damage to mycotoxins in feed, insufficient bile secretion, affected fat-soluble vitamin emulsification, and decreased intestinal health, and poor absorption and utilization of A, D, and E. Studies have shown that there is a direct causal relationship between vitamin A and the integrity, smoothness and brightness of eggshell membranes, vitamin E and egg color and decolorization, vitamin D and eggshell thickness, and broken eggs.
11. In the hot summer, the phytase added in the layer feed is prone to failure due to high temperature, resulting in insufficient available phosphorus and imbalance of calcium and phosphorus. The reasonable ratio of calcium and phosphorus has a great impact on the quality of eggshells.
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