Effects of prepartum supplement level and age of weaning on dam performance and developmental programming of male progeny

A 2 yr study was conducted to determine the effects of prepartum supplement level and age of weaning on cow BW, BCS, milk production, reproduction, calf performance up to weaning, growth performance, feed efficiency, glucose and insulin concentration, and carcass characteristics of male offspring. 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 2 ± 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: 78 ± 11 d of age (EW) or 186 ± 11 d of age (NW). Cow BW was greater (P < 0.01) for cows fed HS at pre-calving (49 ± 11 d prepartum), post-calving (26 ± 11 d postpartum), and post-breeding (81 ± 11 d post-AI) compared to cows fed NS and LS. Cows fed LS and HS also had greater (P ≤ 0.02) BCS at pre-calving and post-calving than cows fed NS. There was no effect (P ≥ 0.60) on calf birth weight or calving ease. Prepartum supplementation tended (P = 0.09) to improve AI conception (NS = 53.2%; LS = 59.2%; HS = 68.8%). Early-weaning increased (P ≤ 0.05) AI conception and post-breeding BW and BCS of the cows compared to cows with calves weaned normal. A significant supplement level × age of weaning interaction existed (P = 0.03) for overall pregnancy. For cows fed HS, EW improved (P = 0.02) overall pregnancy; however, age of weaning did not affect overall pregnancy (P ≥ 0.10) for cows fed NS and LS. At time of early weaning, BW was increased (P = 0.02) for steers from cows fed LS cows compared to steers from cows fed NS. 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 significant (P < 0.01) yr × age of weaning interaction occurred for ultrasound marbling score at time of normal weaning. In yr 1, marbling was decreased (P = 0.04) for EW steers compared iii to NW steers; however, in yr 2, marbling was increased (P < 0.01) for EW steers compared to NW steers. For steer progeny, dam prepartum supplement level did not affect (P ≥ 0.15) growth performance, respiratory health, or carcass traits with the exception of percentage grading Average Choice or greater. A greater (P = 0.03) percentage of steers from cows fed HS graded Average Choice or greater when compared to steers from cows fed NS. Early weaning increased (P < 0.01) steer initial BW and final BW and reduced (P < 0.01) G:F compared to NW steers. A significant (P = 0.02) yr × age of weaning interaction occurred for ADG. In yr 1, EW and NW steers had similar (P = 0.78) ADG; but, in yr 2, EW steers had reduced (P < 0.01) ADG compared to NW steers. The EW steers were younger (P ≤ 0.01) at harvest and had greater (P ≤ 0.02) HCW, yield grade, backfat, and marbling scores compared to NW steers. A yr × age of weaning interaction (P ≤ 0.04) occurred for percentage of steers grading Low Choice or greater and grading Average Choice or greater. In yr 2, early weaning resulted in increased (P < 0.01) proportions of steers grading Low Choice or greater and grading Average Choice or greater, but there were no differences (P ≥ 0.81) in yr 1. The EW steers had greater (P ≤ 0.04) occurrence of single health treatments and mortality due to respiratory disease compared to NW steers. In yr 1, insulin concentration and insulin:glucose was greater (P < 0.01) for EW steers than NW steers, but there were no differences (P ≥ 0.42) in yr 2. In this trial, prepartum supplementation and early weaning improved cow BW, BCS, and reproduction. Although feeding high levels of supplement increased BW and BCS, it did not negatively affect calving ease, milk production, or reproduction. Minimal effects of dam prepartum supplement level on calf performance up to weaning were observed. Early-weaning improved calf growth up to time of normal weaning but had inconsistent effects across years on ultrasound measurements. These data indicate that feeding a high level of supplement to the dam did not affect feedlot performance but did improve iv steer quality grades. Although EW steers had increased respiratory illness, they were younger at harvest and had greater HCW and marbling scores compared to NW steers. The absence of supplement level × wean interactions indicates that these strategies, dam supplementation and early weaning, may have an additive effect on developmental programming