Digestibility Of Different Source And Level Of Zinc In Dairy Goats' Intestinal Tract And Its Effects On Related Endocrine

Zinc is an essential element for animals, and was known as the "life element" because of its physiological function.A long time, nutritionists made a lot of researches of the nutritional value of zinc, found that diet supplemented with zinc can improve animals'growth performance, reproduction and health,and found that the biological value of inorganic of zinc far less organic zinc. So in recent years, people put more attention to study the application of the organic zinc or chelate zinc in animal diets , but the mechanism for its absorption, and the appropriate dosage is still unclear.In order to further study the relative appropriate dosage of zinc in animal diets and its physiological mechanism.The milk goats were studied with different concentrations levels of zinc in sulfate and amino acids chelated forms, and the the zinc's digestibility in the digestive tract and the levels of serum zinc and serum hormone levels was determinated.The results showed that zinc's digestibility in the intestinal of goat milk reached the top when the zinc perfusion level of 80mg/kg ,and the zinc infusion level of 60mg/kg , the zinc's digestibility in the whole digestive tube of milk goat reached the highest levels and the serum zinc to higher level; and on the whole, the digestibility of zinc in the small intestine and the whole intestinal of Zn-AA team are higher than ZnSO₄ group, but serum zinc levels of Zn-AA team were lower than ZnSO₄ group. Of the hormone were found that GH levels decreased in when zinc deficiency, and increased with the dose of zinc supplementation , E2 levels gradually increased with infusion concentration of zinc increasing,and when the concentration of zinc into is high, E2 levels are significantly increased, IGF-1 levels, the ZnSO₄ group showed decreased with perfusion concentrations' increasing of ZnSO₄,but the Zn-AA group decreased first, when injection of higher concentrations of zinc also increased rapidly. It is concluded that: (1) The amino acid zinc was more benefit to be digested and used by the milk goats than zinc sulfate . (2) The appropriate level of Zinc to add in the milk Goats' diet is 60mg 80mg / kg. (3)The serum zinc levels of group Zn-AA were lower compared with group ZnSO₄, suggesting that: It may be the absorption mechanisms are different between the zinc of two forms , may also the metabolic pathwayswere different of two zinc source .(4)The results of Zinc on hormone levels showed that the physiological role of zinc is connection with hormone's secretion and regulation.