Liveweight, ovulation rate, and wool growth responses of light and heavy ewes to differential feeding

Abstract

Abstract Two experiments were conducted to test the liveweight, ovulation rate, and wool growth responses (second experiment only) of light and heavy 4-tooth Romney ewes, selected from large flocks (n = 1400, 1750) and offered 2 pasture allowances (1.2 vs 4.0 kg total DM/ewe per day) for 41-44 days. Mean herbage mass of pastures before grazing was 3220-3560 kg total DM/ha; with compositions of 70-85% grass, 12-20% clover, and 3-10% dead material on a dry matter basis. Starting liveweights (fasted) of the light and heavy ewes were 37.5 vs 49.2 kg (P<0.001, Expt 1) and 40.7 vs 55.4 kg (P<0.001, Expt 2). On an allowance of 4.0 kg DM/ewe per day, the light and heavy ewes in both experiments gained 6-8 kg over the trial period, but on 1.2 kg DM/ewe per day the light ewes gained 1.2–1.5 kg compared with ( −1. 1)–( + 0.6) kg by the heavy ewes (significant allowance X starting liveweight interactions (P<0.01, Expt 1; P<0.001, Expt 2)). Mean ovulation rates were significantly greater (P<0.001) in the heavy ewes (d...