A COMPARISON OF GROWTH-RATES AND CARCASS QUALITY OF STEERS RECEIVING MAIZE SILAGE AS A SUPPLEMENT TO ANNUAL PASTURE OR AS A COMPONENT OF A FEEDLOT RATION

We tested the hypothesis that liveweight gain per hectare could be dou bled in beef steers grazing irrigated annual pastures by increasing st ocking rate from 2.5 to 5.0 steers/ha and supplementing the heavier st ocked treatments with maize silage offered at either 2.4 or 5.6 kg dry matter/steer.day to replicated groups of 4 steers. During an average period on feed of 172 days, liveweight gain was substantially increase d, from 245 kg/ha to either 464 or 576 kg/ha, when maize silage was fe d to steers at 2064 or 4816 kg dry matter/ha, in association with an i ncrease in stocking rate from 2.5 to 5.0 steers/ha. However, such prod uction systems increased the chance of feed shortages, particularly in exceptionally wet winters such as the one experienced in the experime nt. Increasing the rate of supplementary feeding without increasing st ocking rate may not be economically viable. Other strategies, such as lot feeding steers, were also tested. Diets where maize silage constit uted either 46% dry matter (with the balance of the diet comprising wh eat grain, cottonseed meal, urea, bentonite, vitamins and minerals) or 97% dry matter (with the balance of the diet comprising urea, vitamin s and minerals) led to steers achieving liveweight gain of 1.34 and 0. 93 kg/steer.day respectively. Carcasses from steers eating maize silag e fed at pasture or maize silage as a component of lot-fed diets had a t least as adequate fat cover and as good eating quality as carcasses from steers grazing at 2.5 steers/ha.