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Prepartum supplement level and age of weaning: II. Effects of developmental programming on performance and carcass composition of steer progeny
Objectives were to determine the effects of prepartum cow supplement level and age of weaning on growth performance, feed efficiency, glucose and insulin concentrations, and carcass characteristics of steers (yr 1, n = 134; yr 2, n = 147). Mature multiparous Angus × Simmental cows were used in a split-plot design that included 3 supplement levels (supplement = 70% dried distiller’s grains plus solubles (DDGS) and 30% soybean hulls; fed 103 ± 11 d prepartum to 3 ± 11 d postpartum): no supplement (NS), 2.16 kg/d∙hd-1 (LS), 8.61 kg/d∙hd-1 (HS) and 2 ages of weaning: early at 80 ± 11 d of age (EW); normal at 188 ± 11 d of age (NW). Dam prepartum supplement level did not affect (P ≥ 0.15) growth performance, respiratory health, or carcass traits with the exception of percentage ≥ Average Choice. A greater (P = 0.03) percentage of steers from cows fed HS graded ≥ Average Choice when compared to steers from cows fed NS. Early weaning increased (P < 0.01) initial BW and final BW and reduced (P < 0.01) G:F compared to normal weaning. A yr × wean interaction (P = 0.02) occurred for ADG; early weaning resulted in reduced (P < 0.01) ADG compared to normal weaning in yr 2. Although EW steers were younger (P < 0.01) at harvest, they had greater (P ≤ 0.02) HCW, yield grade, backfat, and marbling scores compared to NW steers. A yr × wean interaction (P ≤ 0.04) occurred for quality grade distribution; carcasses from EW steers had increased (P < 0.01) proportions ≥ Low Choice and ≥ Average Choice than carcasses from NW in yr 2. The EW steers had greater (P ≤ 0.04) occurrence of single medical treatments and death due to respiratory disease than NW steers. A yr × wean interaction (P = 0.03) occurred for insulin concentration and insulin:glucose; EW steers had greater (P < 0.01) insulin concentrations and insulin:glucose than NW steers in yr 1. These data suggest overfeeding supplement to the dam did not affect feedlot performance but did improve 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 effects may have an additive effect on developmental programming.
Keywords:
developmental programming, early weaning, maternal nutrition