SUMMARY

T
his study was conducted to determine the effects of zinc supplementation either from inorganic or organic sources on digestibility, blood metabolites and animal performance. Twelve buffalo calves of 11-13 months of age weighing 257.66 ± 26.41 kg were divided into three similar groups of 4 calves each, where G1 was served as control ration, and was fed the basal diet consisting of roughage and concentrate mixture. While the two tested groups were fed the same basal diet, but supplemented with 30 mg Zn//head/day of Zn sulphate (G2). And supplemented with 30 mg Zn//head/day as Zink methionine ( G3). The basal diet contains 28.3 mg/kg Zn, and , additionally, the doses of Zn in the tested groups were orally supplemented. All animals of these groups were fed 80% of their requirements as concentrate mixture and the rest of requirements were covered from wheat straw and alfalfa hay in equal quantities. The daily requirements of energy and crude protein for growing calves were cover according (NRC, 2001). Results indicated that supplemented Zn methionine or Zn sulphate to calves diet increased significantly (p< 0.05) all nutrient digestibilities and feeding value in terms of TDN and DCP as compared with control group. Also, Supplemented Zn methionine for calves' diet increased significantly (p< 0.05) the consenterion of serum Zn, plasma T3 and decreased significantly (p< 0.05) cholesterol concentration as compared with Zn sulphate and control groups. While , serum total protein, Albumin, globulin, and AST were not affected significantly by zinc supplementation from inorganic or organic sources in buffalos calves in comparison with control ration . The body weight and daily gain were significantly higher (P<0.05) for claves fed supplemented Zn-methionine or zinc sulphate ration, than those fed control one . The body weight gain in Zn-methionine group was increased by about 35.29% and 16.59 % than those fed control or zinc sulphate ration , respectively. There was no significant difference in total feed intake among different groups. Supplementation of Zn-meth significantly (P<0.05) improved the feed conversion efficiency and the feed cost/kg weight gain as compared with Zn sulphate and control groups. From the results of this study it could be concluded that supplemented zinc from inorganic or organic sources in buffalo's calves diets improved digestibility and performances of growing buffalo and calves could be recommended that supplement Zn-methionine to growing buffaloes calves rations under Upper Egypt conditions because of its higher bioavailability than Zn sulphate.