Influence of supplementation on the performance of gestating ewes grazing wheat stubble pastures

Abstract

A 3 month field trial was conducted with 72 F1 D'Man X Sardi ewes grazing wheat stubble at a stocking rate of 24 ewes ha −1 to study the effects of concentrate supplementation (Group A, no supplementation; Group B, sunflower meal after 4 weeks of grazing; Group C, sunflower meal after 4 weeks followed by sunflower meal plus barley after 8 weeks of grazing) on biomass, diet quality, ewe liveweight and ewe reproductive performance. Supplementation had no effect on available stubble throughout the trial. Stubble biomass decreased cubically ( P < 0.05) with time of grazing. Residual wheat grain had totally disappeared by Week 8 of grazing. Eighty percent of the crop residue biomass had disappeared by the end of the 12 week grazing period. Chemical composition and in vitro organic matter digestibility (IVOMD) of esophageal extrusa samples were not affected by supplementation. Crude protein and IVOMD decreased quadratically ( P < 0.01) with time of grazing, whereas neutral detergent fiber increased linearly ( P < 0.01). All ewes maintained or gained weight during the initial 4 weeks of grazing. Thereafter, unsupplemented ewes lost weight. Weight changes of B and C ewes during Weeks 5–8, 9–12 or 1–12 were similar. However, a tendency toward higher weight gain was observed for C ewes. Concentrate supplementation tended to increase fertility and lamb crop but not prolificacy rate.