Effect of Organic Zinc Supplementation on Productive and Reproductive Performance of Transition crossbred Cows

Experiment was conducted for 150 d on forty Holstein crossbred cows (530±30 kg b. wt.) and the experimental period had included one-month prior parturition and four months after parturition and were distributed randomly into four treatments and fed super Napier green fodder, paddy straw and concentrate mixture to meet ICAR (2013) nutrient requirements except for mineral mixture. Four experimental rations were formulated viz. BD, Zn_i, Zn_g, and Zn_m in which BD ration had no supplemented zinc, Zn_i (zinc sulphate), Zn_g (zinc glycinate) and Zn_m (zinc methionate). All the forms of zinc were supplemented as per the NRC (2001) nutrient requirements for dairy cattle. Significantly (P<0.05) higher concentration of SOD (units/mg protein) was recorded in Zn_m ration fed cows followed by Zn_g, Zn_i and BD rations. The mean GPx (units/ml) concentration was significantly (P<0.05) lower in the Zn_m ration fed cows followed by Zn_g, Zn_i and BD rations. Milk yield (kg/day) was increased significantly (P<0.05) in the Zn_m ration fed cows. Estrogen (pg/ml) and progesterone (ng/ml) concentrations were significantly (P<0.05) higher in Zn_m ration fed cows when compared to other groups. Reproductive performance was improved by supplementing zinc methionate (Zn_m) and it had shown the best performance in comparison to other treatment groups. With the results, it is inferred that zinc methionate supplementation has improved the productive and reproductive performance by ameliorating the transition stress in crossbred cows.