Effect of season and supplementation during late pregnancy and early lactation on the performance of Zebu cows and calves

The effect of supplementation 8 weeks before and/or 5 weeks after calving in the wet and dry seasons on cow and calf performance was studied using 24 pregnant Zebu cows in each season. During pregnancy the cows were randomly allocated to two treatment groups of 12 cows each and after calving six cows within each pregnancy group were allocated to two post-partum treatments. All cows grazed natural pastures for 8 h / day and the treatments both pre- and post-partum was: grazing only, or grazing and supplementation with cottonseed cake and molasses. The cows were milked twice a day and the calves were allowed to suckle after each milking. The average body weight of the cows after parturition were similar among treatments, but were significantly higher in the wet season. All cows, except the unsupplemented cows during the wet season, gained weight during the first 5 weeks of lactation. Prepartum supplementation of the cows significantly (P < 0.05) increased the birth weights of the calves during both the dry and wet seasons. Calves from pre- and post-partum supplemented cows gained 350 and 307 g/day and calves from unsupplemented cows gained 271 and 185 g/day in the wet and dry season, respectively. The total milk yields for pre- and post-partum supplemented cows were 5.02 and 4.24 kg/d and for unsupplemented cows 2.65 and 2.18 kg/d in wet and dry season, respectively. The cows supplemented either pre- or post-partum generally showed intermediate production results. There were no significant differences in milk composition due to treatment. The best performance of cows and calves was obtained with supplementation both before and after calving, but supplementing during lactation only may give a better return than supplementing during pregnancy.