Emily Croft's MSc Defence

These studies evaluated the effects of metabolizable energy (ME) intake and parity of Angus-Simmental cows during late gestation on cow and calf performance and metabolism. Primiparous (n = 47) and multiparous (n = 109) pregnant Angus-Simmental beef cows were allocated to dietary treatments providing 80 (LME; n = 54), 100 (CME; n = 51) or 120% (HME; n = 51) of their predicted ME requirements 53 days prior to calving. Diets were formulated to meet or exceeded metabolizable protein requirements. After parturition, a common ration was fed. Cows that received HME mobilized less fat prepartum than cows that received LME. Supplementation of ME did not affect cow or calf performance postpartum. Primiparous cows had relatively greater mobilization of body reserves than multiparous cows, and their calves grew slower. These studies demonstrate that supplemental ME during late gestation can improve energy deficits relative to ME restricted cows prepartum, but not postpartum.