The Studies Of 25-dihydroxyvitamin D3 And Phytase On Brailers' Effect And Mechanism

Vitamin D has immune function, it not only can change the body′response to infection, but also can prevent the loss of amino acid through the kidneys. However, vitamin D has no biological activity before its metabolizing into 25-dihydroxyvitaminD3 (25-OH-D₃)which will metabolize into 1,25-(OH)₂-D₃ and 24-25-(OH)₂-D₃ in the kidney, the later are bioactive molecules. 25-OH-D₃ is the only GRAS (generally recognized as safe) level of vitamin D3 metabolites which got U.S.FDA certification and applied in commercial stock. Phytase can improve the utilization of animal phosphorus and reduce the dosage of the inorganic phosphorus in the diret, at the same time it can reduce the inorganic phosphorus emissions in the maure which reduces the environmental pollution. Besides, phytase can improve the utilization of mineral elements.A total of 480 1-d-old Avian chicks were randomly allocated to 4 dietary treatments with 6 replicates of 20 chicks each replicate (10 males and females).Reference standard of feeding broiler, the feeding trial consisted of 1 to 3, 4 to 5 and 6 wk old. The treatment 1 and 2 control direts were formulate to contain calcium and available phosphorus (AP) of 0.9% and 0.45%, respectively; the treatment 3 and 4 control direts were formulate to contain calcium and AP of 0.8% and 0.35%, respectively, for the broilers 1 to 3 wk of age. The treatment 1 and 2 control direts wew formulate to contain calcium and AP of 0.8% and 0.35%, respectively; The treatment 3 and 4 control direts wew formulate to contain calcium and AP of 0.7% and 0.25%, respectively, for the broilers 4 to 5 wk of age.The treatment 1 and 2 control direts were formulate to contain calcium and AP of 0.7% and 0.3%, respectively; The treatment 3 and 4 control direts wew formulate to contain calcium and AP of 0.6% and 0.2%, respectively, for the broilers 6 wk of age. The treatment 1 feed basal diet, For experimental groups,the basal diets were supplemented with 69mg/t of 25-dihydroxyvitamin D₃, 750U/kg of phytase, or 69mg/t of 25-dihydroxyvitamin D3 and 750U/kg of phytase, respectively.Results showed:(1)Supplementing phytase alone, reduced the feed intake of 4 to 5 wk of age and the FCR (P<0.05); no significant difference of other sides, when compared with control group.(2)Supplementing 25-dihydroxyvitamin D3 alone, improved (P<0.05) tibia strength only, some part of growth performance, slaughter indicators, bone index, serum markers was higher (P>0.05) than control group. (3)Supplementing phytase and 25-dihydroxyvitamin D3 reduced the dressing percentage and the abdominal fat percentage(P<0.05),improved the eviscerated rate, tibia strength and contents of Ca in the tibia ash.