The relationship in ewes between voluntary food intake during pregnancy and forage intake during lactation and after weaning

Abstract

ABSTRACT(1) Voluntary intake of forage was measured in 31 Scottish Blackface ewes for the last 14 weeks of pregnancy, throughout lactation, and 15 weeks subsequently. During pregnancy 15 ewes were given hay and 16 dried grass (apparent dry-matter digestibilities in vitro were 51 and 69·6% respectively). All ewes were given the same dried grass during lactation and after weaning (digestibilities 75 and 73% respectively). Body fat was estimated from tritiated water space.(2) Pregnant ewes consumed twice as much digestible dry matter from dried grass (1028 g) as from hay (502 g). Intakes of ewes with twin and single foetuses were similar.(3) During lactation the mean daily intakes of dried grass were 2278, 2610,2612 and 2722 g dry matter respectively, for ewes that had been given dried grass in pregnancy and had single and twin lambs, and for those that had been given hay and had singles and twins. Differences between dried grass and hay were consistently significant (P < 0·01).(4) After weaning the intakes declined rapidly but their ranking remained similar.(5) Lamb birth weights were affected by nutrition during pregnancy, lamb growth rates within twins or singles were not influenced by maternal nutrition during pregnancy or lactation. Differences in ewe intakes during lactation were reflected in ewe body-weight changes.(6) For all ewes, up to 64% of the variation in intake during lactation could be related to factors prevailing before and at lambing (pregnancy diet, ewe weight and fat content) and during lactation (lamb gain and ewe weight change).