Laying hens are 400 days old, which is the later stage of breeding, commonly known as “old chicken”. At this time, the quality of eggshells generally began to decline, the thickness and strength of eggshells decreased, white shells, soft shells, sand shells, thin shells, broken shells, etc. increased, and the damage rate increased.
The main problem is that the physiological reproduction function of the “old chicken” declines, and the reproductive organs age. If accurate nutrition can be adjusted, it can improve the physiological function, improve the quality of the eggshell, delay the decline of egg production, and even make the old hen “Second time”, give full play to egg production performance.
The main cause of poor eggshell quality after 400 days of age
1. The egg is large in the later period, the need for calcium increases, the proportion of the eggshell to the egg becomes smaller, and as the age of the layer hen and the aging of the reproductive organs, the egg production causes overdraft of nutrition, and the calcium and phosphorus in the body accelerate consumption The shell is thinner accordingly;
2. Usually due to calcium and vitamin D deficiency, and calcium exists as a stable substance, vitamin D is easily damaged 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 the old chicken is weakened, and it is often dilute, and the absorption capacity is worse, resulting in a reduction in protein absorption utilization.
5. The reproductive function of old chickens is reduced, the secretion of estrogen is reduced, the function of promoting the 25-hydroxylation of vitamin D3 and protecting vitamin D3 and 25-hydroxyvitamin D3 from enzyme degradation is weak;
6. The eggshell is thin, low in hardness, brittle, and the breakage rate increases, because the supply of calcium is inadequate. In general, it is not calcium deficiency in the feed, but the body’s lack of calcium-transforming substance vitamin D3, which is exactly 25-hydroxyl Vitamin D3;
7. Fatty liver of laying hens in the late stage of breeding is very common, the liver is damaged, the function is weakened, and the metabolic transformation ability is reduced;
8. The body fat of the old chicken is easy to deposit. Due to the deposition of fat in the body, the uterine glands will deposit a certain amount of fat, which will affect the secretion function of the glands, reduce calcium secretion, and make the eggshell thin and brittle;
9. Renal function decline, lack of yang energy, kidney swelling is common, affecting the final transformation of D3;
10. Decreased liver function, especially long-term mycotoxin in feed, insufficient bile secretion, emulsification of fat-soluble vitamins, and reduced intestinal health, and poor absorption of A, D, and E. Studies have shown that vitamin A has a direct causal relationship with eggshell membrane integrity, smoothness and brightness, vitamin E with egg color and eggshell bleaching, vitamin D with eggshell thickness and broken egg.
11. In the hot summer, the phytase added in the feed is likely to fail due to high temperature, resulting in insufficient effective phosphorus and imbalance of calcium and phosphorus. Whether the ratio of calcium and phosphorus is reasonable or not has a great impact on the quality of the eggshell. When calcium and phosphorus are imbalanced, adding cod liver oil is more meaningful.