The effect of body condition and nutrition during late pregnancy on the performance of grazing ewes during lactation

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Abstract
Ewes with body condition scores of 2·6 (T) and 3·3 (F) on day 90 of pregnancy were allocated to one of two feeding regimes calculated either to maintain ewe body reserves (H) or to mobilize body reserves and produce a daily loss of 150 g in ewe body weight (L) during the last 8 weeks of pregnancy. Eight ewes with twin lambs from treatments TL, TH, FL and FH, and six ewes with single lambs from treatment TH, were grazed for the first 10 weeks of lactation at a mean daily herbage dry matter allowance of lOOg/kg live weight.Feeding treatments applied during pregnancy produced differences in ewe live weights and body condition scores at lambing (68·6, 72·4, 76·7, 831 (s.e. 2·40) kg and 1·9, 2·9, 2·8, 31 (s.e. 011) for treatments TL, TH, FL and FH respectively) that persisted through lactation, but had no effect on herbage organic matter intake by ewes (mean 21 (s.e. 0·05) kg/day) milk yield (2·4 (s.e. 0·13) kg/day), lamb growth rate (mean 245 (s.e. 4·7) g/day) or herbage intake by lambs in weeks 7, 8 and 10 (mean 0·23, 0·28 and 0·36 (s.e. 0·007) kg/day).Ewes with single lambs, when compared with ewes with twins, had similar intakes of herbage organic matter (mean 2·2 (s.e. 0·14) kg/day), produced 0·28 less milk (mean 1·7 (s.e. 010) kg/day) and increased in weight (mean 5·0 (s.e. 1·96) kg). Single lambs had significantly higher growth rates (322 (s.e. 13·1) g/day) overall but had similar intakes of herbage organic matter in weeks 7, 8 and 10 (means 0·25, 0·29 and 0·39 (s.e. 0·03) kg/day).The range of ewe body condition and feeding in late pregnancy examined in this experiment had little subsequent effect on milk production by the ewes suckling twin lambs, given a plentiful supply of herbage.