T.J. TIERNEY¹ and W.J. TAYLOR²

¹Queensland Department of Primary Industries, Coolum Research Station, 4573 Coolum.
²Queensland Department of Primary Industries, P.O. Box 689, Rockhampton 4700

Abstract

The reproductive performance of Hereford cows and growth rates of cross-bred calves grazing pangola grass (Digitaria decumbens) fertilised annually with a mean 390 kg N ha^–1 for three and a half years are reported. A six paddock rotational system and a set-stocking management system, both with an overall stocking rate of 6.25 breeders hd^–1 were compared. There was no significant difference between the pasture systems in either cow or calf performance. Mean pregnancy and weaning rates, weaning weight and calf liveweight weaned per cow joined were 90 and M%, 197 and 151 kg respectively. Calf mean daily gain from birth to weaning was 0.67 kg. Years affected calf birth weights, calf gain to 71 days and to weaning, cow weights and gestation length. Older cows were heavier, conceived earlier, had longer gestation lengths, had heavier calf birth weights, higher calf gains to 71 days and to weaning and heavier calf weaning weights than younger cows. Lactating cows gained less and were lighter at weaning than non-lactating cows. The only animal factor influenced by the grazing system was a longer gestation length in the rotation compared to the set-stocking. Male calves were heavier at birth, had higher gains to 71 days and heavier weaning weights.
Pasture availability was generally greater on the rotation than the set-stocking. Pasture nitrogen in vitro digestibility and faecal nitrogen and phosphorus remained similar on both systems. Weed invasion in the rotation system was much less than in the set-stocking system.