Vitamin A deficiency is likely to cause a series of nutritional metabolic dysfunctions in laying hens, resulting in reduced fertility, reduced production performance, and reduced production life. To this end, this article briefly describes the causes of vitamin A deficiency in laying hens and preventive measures in order to attract the attention of laying hens.
1 The main role of vitamin A in laying hen production
Vitamin A plays an important role in maintaining the health and normal physiological functions of mucosal epithelial tissues in various organ systems of laying hens and maintaining normal vision and reproductive function of laying hens. The manifestation of vitamin A deficiency is: epithelial corticalization. The early stages are mucosal degeneration of the respiratory tract, oral cavity, salivary gland, eye, lacrimal gland, intestine, kidney and cloaca, which causes the laying hen to be highly sensitive to infection, often with colds and pneumonia, diarrhea, loss of appetite, weight loss, followed by more Tears, keratitis, dry eye, corneal cloud, and sometimes permanent blindness. The lack of vitamin A in the laying period of laying hens will result in a significant decrease in the production of laying hens. The small eggs have no yolk eggs, plaques, and soft-skinned eggs. Malformed eggs or eggs hatch chicks blind, during the growth period, vitamin A deficiency is mainly blinking and night blindness. If the concentration of vitamin A in the plasma of Isa chicken is less than 20 micrograms and 100 ml, it can be considered that there is a deficiency; when the concentration is reduced to 10 micrograms and 100 ml, the deficiency is considered; when the concentration is reduced to 10 micrograms and 100 ml, it indicates storage in the liver. Vitamin A has been reduced to a critical point.
The amount of vitamin A required is generally expressed in carotene. Carotene is a precursor of vitamin A. 1 mg of carotene is equivalent to 1667 IU of vitamin A for monogastric animals. It is internationally recognized that 1 ml of carrot is equivalent to 400 IU of vitamin A. This ratio relationship can be used to calculate the need and amount of vitamin A in the feed.
2 the main cause of vitamin A deficiency in laying hens
(1) Insufficient intake of food intake
First, the vitamin A and carrots in the feed are destroyed, the quality of the feed crops, as well as the harvest, processing and storage of the crops, the vitamin A content in the feed is reduced; the feed storage time is too long, mildewed, rained and long-term sunlight Exposure can reduce carotene and vitamin A by 70%-80%. Second, long-term feeding of vitamin A and carotene-deficient feeds is most likely to cause insufficient intake. Third, the feeding ability of laying hens is poor. For example, when the ill is sick, the reduction in feed intake directly affects the intake of vitamin A, resulting in insufficient intake.
(2) digestion and malabsorption
First, dysfunctions such as the gastrointestinal tract, liver, pancreas and thyroid gland not only affect the digestion and absorption of vitamin A and carotene, but also affect the anabolism of vitamin A in the body. The second is the nutritional status of laying hens, that is, the nutritional factors and the gastrointestinal environment affect digestion and absorption.
When there is a lack or imbalance, the gastrointestinal tract is too acidic and easy to cause metabolic disorders will reduce the digestion and absorption of vitamin A.
(3) Vitamin A needs to increase
During the physiological period of growth and egg production, the body's need for vitamin A increases. Under pathological conditions, such as fever, tuberculosis, parasitic diseases, etc., the consumption of vitamin A in the body increases, and the demand increases. When the feed contains lipid oxidase anti-vitamin A and the nitrogen content in the feed is too high, vitamin A will increase the required amount.
3 specific solutions in production
(1) Do a good job in scientific production and storage of feed
Feed crops should be scientifically planted and harvested at the right time. The feed should not be applied with too much nitrogen fertilizer; the feed should be processed reasonably and scientifically adjusted to improve the utilization value and improve the palatability; the feed should be kept in storage, protected from rain, exposure and long-term storage and mildew. Deterioration to reduce the loss of vitamin A in the feed.
(2) Reasonable preparation of laying hen diet
The feed should be combined with the total amount of nutrition and nutrition to ensure the content of vitamin A and carotene. Every vitamin should be added as much as possible and a safe supply dose should be obtained. In addition, the protein, lipid defense, trace elements, etc. in the diet should be sufficient and balanced to ensure the full absorption and utilization of vitamin A in the nutritional needs of laying hens. NRC pointed out that the vitamin A requirement in laying hens is about 200 IUkg; the recommended amount of vitamin A in laying hens for laying hens and laying hens is 100000-125000 IU and 50,000-75000 IU, respectively.
(3) Scientific feeding, timely treatment
The content of vitamin A in the laying hens is generally reduced in autumn and winter, and the least in March, the storage of vitamin A in the liver is also the least in 3-4 months. Therefore, the supply of vitamin A should be strengthened in feeding. Add supplement or cod liver oil preparation in winter. Under low temperature, high temperature or transportation, driving and other stress conditions, generally increase the supply of vitamin A by 0.5-1 times as needed to ensure the health of the laying hens under stress conditions and the full production potential. . In case of laying hens, vitamin A should be added at a rapid dose or intramuscularly (440 IUkg); or fish oil should be taken orally (dose according to the instructions). Because of the similar and common effects of vitamins and mutual protection and synergy, vitamin A supplementation should also be supplemented with multiple vitamins to ensure the trace element requirements of laying hens. In the treatment and prevention of vitamin A deficiency, trace elements and zinc should be supplemented at the same time to improve the cure rate.
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