Effect of supplementary feeding and herbage mass on the intake and performance of grazing ewes in early lactation

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Abstract
1. Two experiments were conducted to examine the effects of a cereal-based supplement and herbage mass on the intake and performance by Border Leicester × Scottish Blackface ewes nursing twin lambs in early lactation.2. In one experiment 16 ewes, individually penned, were given one of four amounts of supplement (0, 320, 640 and 960 g organic matter per ewe per day) and offered ad libitum freshly-cut perennial ryegrass herbage (organic-matter digestibility 82%). Intake of herbage and total organic matter digestibility declined linearly with increasing intake of supplement (0·84 g organic matter of herbage per g organic matter of supplement and 0·50 percentage units per 100 g organic matter of supplement respectively).3. In the second experiment three amounts of supplement (0, 480 and 960 g organic matter per ewe per day) were offered individually to groups of seven ewes grazing a perennial ryegrass sward of high digestibility, maintained at herbage masses of either 500 or 750 kg organic matter per ha. A further group of seven unsupplemented ewes were grazed on the same sward maintained at 1500 kg organic matter per ha. Intakes of herbage and digestible organic matter by ewes, and lamb live-weight gain, were all significantly greater and ewe live-weight loss significantly less at herbage masses of 750 and 1500 tha n at 500 kg organic matter per ha (P <0·05). The mean decline in herbage intake was 0·93g organic matter per g organic matter supplement consumed. Amount of supplement had no significant effect on lamb live-weight gain at either weight of herbage nor on ewe live-weight loss at the 750 kg organic matter per ha herbage mass. At 500 kg organic matter per ha herbage mass, intake of digestible organic matter was significantly greater and ewe live-weight loss was significantly less for 960 than for 0 and 480 g organic matter per day amounts of supplement (P <0·05).