Why is vitamin nutrition so important in late laying hens

The vitamin nutrition of laying hens in the late laying period is often ignored. According to the conventional thinking, the dietary nutrient concentration of laying hens in the late laying period should be appropriately reduced when preparing the late-laying materials. Many people have a misconception that the vitamin level will also be decreased when the nutrient concentration is reduced.

1. Characteristics of late laying period

In the later stage of egg production, the laying performance of chickens gradually decreases, the eggshell gradually becomes thinner, the breakage rate gradually increases, and the nutrition required for egg production gradually decreases. The excess nutrition may turn into fat and make the chickens fat. At the same time, due to the gradual decline of the antibody level in the later stage of laying, the resistance to diseases is gradually weakened and they are more sensitive to various stresses. If the level of vitamin use is reduced during this period, the deficiency will appear faster and more severe than during the growing, peak period.

2 The role of vitamin nutrition

The main reason is that the aging laying hens have decreased antioxidant capacity and immune system, which lead to decreased egg production performance and egg quality, and thus increased vitamin requirement. Vitamin A deficiency, for example, not only disrupts the mucosal barrier, but also, more importantly, reduces many immune responses, especially serum IgG, IgA and IgM, inhibits lymphocyte response to antigens, and reduces the activity of natural killer cells. Therefore, the immune system of laying hens is weakened in the later stage. If vitamin A is insufficient again, the disease resistance will be very poor. Dietary vitamin A and vitamin K3 can improve lipid metabolism function and decrease liver index of laying hens in late laying period. Supplementation of 120 mg/kg vitamin E and 240 mg/kg vitamin E in late laying diet can significantly improve laying performance and egg quality of laying hens. Appropriately increasing dietary calcium level in late laying period is beneficial to performance of laying hens, but vitamin D3 deficiency can reduce performance and even cause production suspension.

3 Stress vitamin needs

On the other hand, the resistance of laying hens in the later stage of laying is gradually weakened and they are more sensitive to various stresses. In this period, the vitamin level required for anti-stress is higher. Under normal physiological conditions, the animal body can produce a variety of endogenous antioxidant free radical active substances, which can continuously remove free radicals, so that the production and removal of free radicals in the body are in a state of balance. However, when animals are stimulated by oxidative stress, the balance in the body will be broken, and lipid peroxidation will occur. The endogenous and exogenous antioxidant systems of the body will produce responses to remove free radicals, so as to maintain the stable state of free radicals in the body. Therefore, the needs of the animal body for antioxidant nutrients may be changed. In the later stage of laying, the laying hens are more sensitive to stress, so the nutritional need for vitamins will also increase. Sometimes the laying level is unstable, rising and falling, and stress is the main reason. Therefore, it is very important to apply vitamins against stress in the later stage.

To sum up, vitamin nutrition in the late stage of egg production cannot be ignored. Reasonable vitamin supplement, combined with good feeding and management, is the key to prolong the peak of egg production, delay the decline of egg production rate and improve the quality of eggshell in the late stage.