The Effect of Early Calf Weaning on Feed Intake, Growth, and Postpartum Interval in Thin, Brahman-Crossbred Primiparous Cows

Abstract

The effects of early weaning (EW) on productivity of primiparous Brahmancrossbred cows were investigated. Following calving, 12 primiparous cows were randomly allotted to be EW (n = 6) or were left with their calves to be normal weaned (NW; n = 6). All cows were maintained in separate, individual pens (114 m2): NW cows with their calves, and EW cows without their calves. Calf age at the time of EW (January 2; d 0) did not differ among treatments (average days postpartum = 93 ± 22). Cow BW and body condition score (BCS) (nine-point scale) did not differ at the time of EW (average BW = 354 ± 25 kg; average BCS = 3.7 ± 0.7). Following early weaning, all cows were provided free choice access to chopped stargrass (Cynodon spp.) hay and supplemental concentrate at an amount required to support a targeted ADG of 0.57 kg/d. Individual cow BW and BCS were measured on d 0, 21, 42, and 70. Postpartum interval was calculated by the determination of plasma progesterone concentrations. Cows were determined to be cycling on the 1st wk of 2- wk samplings containing >1.0ng progesterone/mL. Overall, the NW cows had a lesser ADG (0.51 vs 0.66 kg/d; SEM = 0.02), but BW differed (P<0.05) only on d 21 (382 vs 322kg for EW and NW cows, respectively). Cow BCS increased similarly for cows on both treatments and did not differ throughout the study. Throughout the 10-wk study, NW cows and their calves consumed 59% more (P<0.001) TDN than did EW cows. Although BW was similar at the end of the 10-wk study, more (P=0.08) EW cows were cycling than NW cows (EW: 5 of 6 cows cycling; NW: 2 of 6 cows cycling). Compared with NW cows, the initiation of postpartum estrus occurred 8 wk earlier (P<0.005) in EW cows. By 2 wk following early weaning, 5 of 6 EW cows were cyclic vs 1 of 6 NW cows. These data indicate that early weaning thin, primiparous cows results in a substantial reduction in the amount of TDN required to support cow BW gain. Early weaning also is effective in initiating postpartum estrus in these cows.