0775 Effects of Maternal Dietary Restriction During the Second Trimester on Offspring Growth and Feedlot Performance

This study determined the impacts of maternal dietary insult during the second trimester on offspring growth and early feedlot performance. Angus-influenced commercial cows (n = 34) were naturally bred to a purebred Angus sire. During preparturition, individual cow served as the experimental unit for one-way ANOVA. During 84 d of mid gestation, cows were stratified into two groups, maintenance (n = 16) and restricted (n = 18), by initial weights (P = 0.804) and BCS (P = 0.723). Restricted cows were provided with lower forage biomass (1,662 kg/ha, DM) in comparison with maintenance (2,309 kg/ha, DM). Following the insult period, restricted cows had a mean BCS 1.55 lower (P = 0.001) than maintenance cows and a BW difference of 85.3 kg (P = 0.024). Dams were commingled and uniformly managed following mid gestation. Calves were weaned approximately 215 d of age and placed on a background diet for 7 wks before entering the feedlot phase where calves were kept in individual pens and fed a grower ration ad libitum. Calves BW were measured at birth, weaning, and every 28 d of the feedlot phase. Ultrasound was used for measurement of BF and REA during the feedlot phase. Calf temperament was evaluated at weaning and during the feedlot phase. Serum glucose, insulin, IGF-1, and cortisol were determined for calves at weaning, 1 wk before the feedlot phase, and the last day of the feeding trial. One-way ANOVA was used to determine impacts of fetal programming on calves. Individual calf served as the experimental unit. Calf BW at birth, weaning, and during feeding showed no differences (P ≥ 0.245). No differences were determined for ADFI (P ≥ 0.428), ADG (P ≥ 0.338), G:F (P ≥ 0.273), REA (P ≥ 0.285), or BF (P ≥ 0.416) during the feedlot stage. Concentrations of glucose (P ≥ 0.504), insulin (P ≥ 0.224), IGF-1 (P ≥ 0.107), and cortisol (P ≥ 0.709) were found to be similar at all time points. Restricted calves were found to be more excitable, with greater temperament scores at weaning (P = 0.026). Recent work has indicated that fetal programming alters progeny carcass characteristics. However, concerns for negative impacts on performance of progeny exist. This study determined little impact on calf performance during early feedlot stages