Nutritional options and implications for maximum growth rate of steers.

摘要

Estimates of age and weight at mature size are required for development of decision-support and mathematical models to describe beef growth. Interim results from an experiment designed to quantify liveweight gain of steers from weaning to mature size are reported. Three groups of 28 steers were fed for 2 years from weaning (8 months) to 32 months old on the following treatments: resident, ryegrass-white clover based pasture (R); a high-quality pasture option based on annual ryegrass in winter and spring, and red clover and lotus in summer and autumn (HQ); and a 70% maize grain:30% silage diet offered under feedlot conditions (F). Average daily gain from weaning to 30 months and liveweight at 30 months were 0.69 and 709, 0.78 and 772, and 0.91 and858 kg for R, HQ and F treatments, respectively. Feedlot steers had a greater fat depth over the 12/13th rib than either of the pasture-fed treatments at the same age. In addition, both pasture groups showed seasonality in liveweight gain, with periods of low liveweight gain in late autumn and winter of the second and third years.