Supplements for Merino weaner sheep grazing mature pastures in summer and autumn

Abstract

Two grazing experiments were conducted to study the short term effects (up to the following shearing in November) on Merino weaner sheep of supplementing senescent perennial ryegrass-subterranean clover pasture with oaten grain, lupin grain and soya bean meal from January to the beginning of April. In the first experiment, weaners grazed hay aftermath or mature uncut pasture. The supplements given daily were: none, oaten grain 0.28 kg/sheep, lupin grain 0.24 kg, soya bean meal 0.15 kg, soya 0.10 kg + lupin 0.08 kg, lupin 0.16 kg +soya 0.05 kg. The second experiment was designed to produce a response curve, relating the amount of lupin grain supplement (0-0.35 kg/sheep in 50 g increments) offered daily to weaners on hay aftermath, to their growth and wool production. A further group was given 0.25 kg oaten grain/sheep. In the first experiment, the difference between pastures was apparent in liveweight at the end of supplementation in early April (24-8-22.0 kg), liveweight in August (31 SO-29.2 kg), wool growth during supplementation (0.89 and 0.70 kg) and greasy fleece weights (4.2 and 3.8 kg) (hay aftermath and uncut pasture respectively). Supplemented groups were 2-3 kg heavier than unsupplemented ones but differences between groups given different supplements were not significant except those between lupin and oat fed weaners on hay aftermath at the end of supplementation. Fleece weights were not significantly affected by the type of supplementation but animals on predominantly soya bean meal supplements had higher greasy fleece weights than the controls. Liveweights at the end of supplementation in experiment 2 did not respond to increased amounts of lupin grain above 0.2 kg and there was no significant response in wool growth to increments of lupin grain. Liveweights at shearing were significantly different only in groups offered the largest (0.35 kg) and the smallest (0.05 kg) amounts of lupin grain. Sheep in the control group were lighter than all others except those given the smallest amount of lupin grain. The only significant difference in greasy fleece weights (0.7 kg) was between those from control sheep and sheep given the highest level of supplementation. In both experiments there was evidence of substitution of oaten grain for pasture, but this did not significantly reduce liveweights or fleece weights relative to those of sheep in groups receiving the same amount of energy in lupin grain. Final liveweights were influenced as much by liveweights at the start of the experiments as by the type or amount of supplement offered to the weaners in summer.