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Prepartum supplement level and age of weaning: I. Effects on pre- and postpartum beef cow performance and calf performance through weaning
Objectives were to determine the effects of prepartum supplement level and age of weaning on BW, BCS, milk production, reproduction, and calf performance up to weaning in a fall-calving system over 2 yr. Mature multiparous Angus × Simmental cows (yr 1, n = 326; yr 2, n = 383) were used in a split-plot design that included 3 supplement levels (supplement = 70% dried distiller’s grains plus solubles and 30% soybean hulls; fed 103± 11 d prepartum to 3± 11 d postpartum): no supplement (NS), 2.16 kg/d∙hd-1 (LS), or 8.61 kg/d∙hd-1 (HS) and 2 ages of weaning: early at 80 ± 11 d of age (EW) or normal at 188 ± 11 d of age (NW). Cow BW for cows fed HS was greater (P ≤ 0.04) at pre-calving (55± 11 d prepartum), post-calving (27 ± 11 d postpartum), and post-breeding (81 d post-breeding) compared to NS and LS cows. Cows fed HS had increased (P ≤ 0.02) pre-calving, post-calving, and post-breeding BCS, relative to cows fed NS, with no effects (P ≥ 0.60) on calf birth weight or calving ease. Prepartum supplementation tended (P = 0.09) to improve AI conception. Early weaning resulted in increased (P ≤ 0.05) AI conception and post-breeding BW and BCS relative to normal weaning. A significant supplement level × wean interaction existed (P = 0.03) for overall pregnancy. For cows fed HS, EW improved (P = 0.02) overall pregnancy; however, weaning age did not affect (P ≥ 0.10) overall pregnancy for NS and LS cows. At time of early weaning, BW was increased (P = 0.02) for steers from LS cows compared to steers from NS cows. Steer BW at time of normal weaning, and ADG between early and normal weaning, was greater (P < 0.01) for EW steers compared to NW steers. A yr × wean interaction (P < 0.01) occurred for ultrasound marbling score at time of normal weaning. In yr 1, marbling was decreased (P = 0.04) in EW steers compared to NW steers; however, in yr 2, marbling was increased (P < 0.01) in EW steers compared to NW steers. These data suggest prepartum supplementation and early weaning improved cow BW, BCS, and reproduction. There were minimal effects of dam prepartum supplement on calf performance up to weaning. Early-weaning improved calf growth, but had inconsistent effects across years on ultrasound measurements.
Keywords:
beef cattle, early weaning, prepartum supplementation