Effect of herbage DM allowance on the immediate and longer term performance of young Friesian steers at pasture

Abstract

The cumulative effects of different levels of herbage DM allowance on pasture production and quality, and on immediate and longer term animal production by Friesian steers, were investigated in two experiments. In Experiment 1 allowances were 3.0, 4.5, 6.0, and 7.5 kg DM/100 kg live weight (LW) and in Experiment 2 aIlowances were 5.0, 7.5, 10.0, and 12.5 kg/lOO kg LW. Pasture production was not significantly affected by allowance in either experiment but utilisation, both per grazing and over the whole season (December to May) , declined significantly as allowance was increased. In vitro digestibility of pasture also declined as allowance increased; this was associated with a build-up of dead matter in the swards. Live-weight gain per animal was linearly related to allowance in Experiment 1 and curvilinearly related to allowance in Experiment 2 with little response above an allowance of 10.0 kg DM/100 kg LW. In both experiments carry-over effects were measured over 7-week periods during which cattle received a restricted pasture allowance together with wilted pasture silage ad libitum. Liveweight and carcass gains were high during these periods but no compensatory growth occurred.