Vol. 12, Special Issue 11 (2023)

Author(s):
K Sushma, M Venkateswarlu, D Nagalakshmi, RMV Prasad, B Swathi and N Nalini Kumari

Abstract:
A study was carried out to evaluate the effect of supplementing different sources of zinc in crossbred cows during transition and early phase of lactation. 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 in it, 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. Blood samples were collected at -15, 0, +15, +30 and +60 d post calving (0 indicates day of calving) and analyzed for serum zinc concentration during the experimental study. The zinc content in the various feed ingredients were analyzed. As part of routine management, the postpartum cows were observed twice a day by trained farm personnel for the occurrence of estrous based on vaginal discharges and behavioural signs. The mean values of serum zinc concentration (µmoles/ liter) in crossbred transition cows for BD, Zn_i, Zn_g and Zn_m fed rations was 0.91, 0.97, 1.08 and 1.19, respectively and the values were significantly (p<0.05) different among the groups. The first heat after calving were 61.80, 55.50, 52.30 and 51.80 for BD, Zn_i, Zn_g and Zn_m, respectively. With the supplementation of organic zinc sources the anoestrum period has been decreased in Zn_g and Zn_m ration fed cows compared to withot zinc and inorganic zinc treated animals.