LIMITED NURSING EFFECTS ON REPRODUCTIVE PERFORMANCE OF PRIMIPAROUS AND MULTIPAROUS COWS AND PREWEANING CALF PERFORMANCE

Abstract

Effects of limited nursing and parity of the dam on cow reproductive and calf gain performance were determined in two experiments involving 97 beef cow-calf pairs. Fall-calving (exp. 1) and spring-calving (exp. 2) primiparous (P) and multiparous (M) cows were assigned to control (C) or limited nursing (L) treatments at 21–28 d postpartum. Cows and calves continued on nursing treatments until first estrus was detected, or until 42 d had elapsed. Nursing treatment and parity of the dam influenced estrous activity in exp. 1. Higher (P < 0.05) percentages of multiparous dams and of L treatment cows were observed in estrus during the treatment period. A 5.6-d reduction (P < 0.10) in postpartum interval to first estrus (PPI) was observed for L cows observed in estrus during treatment periods, and a 16.2-d reduction (P < 0.01) occurred for L cows when all cows observed in estrus during or after the nursing treatment periods were compared to control cows in exp. 1. In exp. 2, nursing treatment and parity of the dam did not significantly affect PPI. Nursing treatments did not affect pregnancy rates in exp. 1, but M cows had higher (P < 0.01) pregnancy rates than P cows. Average daily gains (ADG) were lower (P < 0.10, exp. 1; P < 0.01, exp. 2) for L calves compared with C calves during treatment periods. The L calves did not overcome ADG reductions suffered while on the L treatment by weaning time, and 205-d adjusted weights of L calves were 25 kg lower (P < 0.05) than C calves in exp. 1. Potential improvement in reproductive efficiency resulting from limited nursing must be evaluated with regard to reduced preweaning calf performance. Key words: Cattle (beef), postpartum interval, estrus, once-daily nursing, weaning weight, first estrus