Evaluation of five Mediterranean annual pasture species during early growth

Abstract

Pasture factors causing differences in the liveweight gain of sheep stocked at 10 sheep ha-l on continuously grazed swards of five annual species were examined during autumn and early winter. Differences in liveweight gain were due to the availability of the pasture species for prehension by grazing sheep, and depended on the weight of pasture offered and also on the growth form of the grazed plants. Subterranean clover and the volunteer species, silver grass and erodium, rapidly assumed a prostrate form under continuous grazing, thereby restricting apparent intake. Wimmera ryegrass changed less in growth form in response to grazing and for this reason liveweight gain on ryegrass in autumn was better than on clover, silver grass, and erodium. These species differences were reflected in the "critical" weight of herbage required for sheep to maintain their liveweight. Critical weight was lowest in the erect-growing Wimmera ryegrass (c. 130 kg ha-l) and highest (635 kg ha-l) in the prostrate erodium.