Abstract:
The aim of this study was to quantify the effects of nutrition during pregnancy and lactation on birth weight and growth to weaning of Piedmontese and Wagyu sired calves. This research was also conducted to provide animals for long-term studies on the consequences of growth early in life. During 2 breeding cycles, Hereford cows were managed within low or high pasture-based nutritional systems from about 80 days of pregnancy to parturition. During lactation, the calves and their dams remained on the low or high nutritional system or crossed over to the alternative system. From commencement of the nutritional treatment during pregnancy until parturition, and then during lactation, cows on low nutrition lost an average of 45 and 23 kg liveweight, respectively, and those on high nutrition gained 55 and 40 kg, respectively. Calves of Wagyu sires weighed less at birth (31.0 v 35.9 kg, s.e. = 0.31 kg) and weaning (182 v. 189 kg, s.e. = 2.26 kg) than those of Piedmontese sires. Calves of cows on low nutrition during pregnancy weighed less at birth than those of cows on high nutrition (32.5 v. 35.2 kg, s.e. = 0.32 kg). Low nutrition during pregnancy adversely influenced birth to weaning ADG (676 v. 759 g, s.e. = 9.2 g), weight gain (145 v. 160 kg, s.e. = 2.1 kg) and liveweight (177 v. 195 kg, s.e. = 2.3 kg) of calves at weaning. The nutritional system during lactation had greater effects on ADG (618 v. 816 g, s.e. = 9.2 g), weight gain (131 v. 174 kg, s.e. = 2.1 kg) and liveweight (164 v. 207 kg, s.e. = 2.3 kg) of calves at weaning than the nutritional system during pregnancy. Overall, the responses to the nutritional treatments were consistent for the progeny of both sire-genotypes.