EFFECT OF POSTPARTUM NUTRITION AND COW BODY CONDITION AT PARTURITION ON SUBSEQUENT PERFORMANCE OF BEEF-CATTLE

Seventy-two cows were used in each of 2 yr to study the effect of body condition (BC) and postpartum grain feeding on cow and calf weights and on reproductive traits. Cows reached a BC score of 4 or 6 by parturition and were fed 0 or 4 kg mixed grain d-1 during the postpartum period. All cows were fed grass silage throughout the trial. Grain feeding had no effect on weight gains but increased BC of the lactating cows. Presence of ovarian follicles, uterine involution and pregnancy rate were the only reproductive parameters generally affected by grain feeding. Body condition score had no effect on calf performance, but an increase in BC at parturition yielded an improvement of most of the reproductive traits measured. No interaction was observed between BC and postpartum grain feeding. suggesting that all cows responded similarly to the treatments. Under the conditions of this trial, it was shown that BC at parturition was an important factor affecting cow performance, but the reproductive intervals were directly related to the physiological state of the cow at the beginning of the breeding season.