Significant effect of zinc on piglets
Nutritional and physiological role of zinc
Zinc is distributed in all tissues of the body, and the concentration of zinc is higher in organs such as muscle, liver, and fur. Zinc plays a very important role in many aspects such as maintaining animal growth and development, material metabolism and immune function. Its nutritional functions are mainly: the first to participate in the composition of enzymes in the body. Zinc is a component of more than 40 enzymes in the body and an activator of more than 200 enzymes. In different enzymes, zinc plays a variety of biochemical roles such as catalyzing decomposition, synthesis, stabilization of enzyme protein quaternary structure, and adjustment of enzyme activity. The second is involved in maintaining normal morphology, growth and health of epithelial cells and coat. Its biochemical basis is related to the involvement of zinc in the metabolism of cystine and acid-mucopolysaccharide. The third maintains the normal action of hormones. Zinc forms soluble polymers with insulin or proinsulin, which is beneficial to the physiological and biochemical effects of pancreatic islets. Zinc plays a role in the formation, storage and secretion of other hormones. Fourth, maintain the normal structure and function of the biofilm and prevent the biofilm from suffering from oxidative damage and structural deformation.
Zinc requirement for piglets
During lactation, each piglet sucks about 0.5kg per day, and the daily gain is 0.1-0.2kg. The zinc content of milk is generally 4.94mg/kg, which can generally meet the normal growth needs of piglets. However, it should be noted that at this stage, piglets do not have the ability to self-regulate zinc absorption and excretion, so be careful when adding them.
In the 10-40kg stage, the zinc requirement of piglets is translated by Ding Jinyong. In 1992, there are different reports on the zinc requirement of piglets, and most of them are between 80ppm and 100ppm. Xu Xiaoyi and others believe that the zinc requirement of 7-20kg piglets is 98ppm, Xu Zhenying suggested 100ppm, and Wang Xiaofei's research believes that 150ppm of copper, iron and zinc in the diet of 10-20kg piglets is the best. The average amount of French, Soviet, Japanese, Chinese) standards is 82.6ppm.
Zinc deficiency and excess
The zinc requirement of pigs is affected by calcium, phosphorus, iron, copper, phytic acid, etc. in the feed. The absorption rate of zinc by piglets is between 40% and 60%. There are many reasons for the lack of zinc in pigs, mainly including the low effective content of zinc in the feed and the use of high copper in recent years; methionine and cysteine will also accelerate the excretion of zinc from the body; liver disease can also cause zinc deficiency. Therefore, pigs are prone to zinc deficiency, especially in newly weaned piglets. Zinc deficiency in the diet, piglets mainly show as follows: (1) Appetite and growth rate are significantly reduced. (2) Incomplete keratosis: The epithelium of the skin and esophagus is thickened or hyperkeratotic, manifested as skin inflammation, crusting, hair loss, vomiting, diarrhea, and malnutrition. (3) Bone deformation: When zinc deficiency occurs, cartilage formation is blocked, and the activity of phosphatase in bones is reduced, resulting in skeletal dysplasia, shortening and thickening of long bones.
Insufficient zinc can be harmful to piglets, and too much zinc can be harmful to piglets. Excessive zinc can reduce the DNA, RNA and protein of T and B lymphocytes in the thymus, bone marrow, and spleen of piglets, reduce the proliferation of cells, and reduce the phagocytosis and bactericidal power of peripheral blood granulocytes and peritoneal macrophages (Zhu Jianjin, 1996). ). Excessive zinc can cause secondary deficiency of iron and copper, resulting in anemia and slow growth of piglets. However, in practice, poisoning caused by excessive zinc generally does not occur, because the range between the normal physiological requirement of zinc and the poisoning amount is very large, pigs can tolerate 20 to 30 times the normal amount, and excessive zinc content in the feed can Make piglets anorexia, so as to avoid the harm to the body caused by excessive zinc.
The role of high zinc diet
In recent years, a large number of studies have been carried out on the effect of high-dose zinc (1000-3000ppm) in piglet diets at home and abroad, and it has been proved that high zinc can reduce early weaned piglets diarrhea, increase daily weight gain, and improve feed compensation. Feeding for two weeks after weaning is better. However, there are also a small number of reports with opposite results. Regarding the mechanism of high zinc growth-promoting action, no consensus has been formed yet, and further research is needed.