The effect of interaction of ewe and lamb genotype on milk production of ewes and on growth of lambs to weaning

Abstract

Single and twin purebred Scottish Blackface lambs born to Blackface ewes, and Suffolk cross lambs born to East Friesland × Blackface ewes, were removed from their dams at birth and cross-fostered to give all combinations of breed of ewe, breed of lamb and number of lambs suckled, with no ewe rearing her own lamb.Milk production was measured on 1 day/week for 14 weeks. The effect of ewe breed was significant in all weeks, with the East Friesland cross ewes having a higher peak and a more sustained level of production than the Blackface ewes. Ewes suckling twins produced more milk than those suckling singles. Breed-of-lamb effect was significant during the first 5 to 6 weeks of lactation, with crossbred lambs inducing a higher milk output than Blackface lambs, irrespective of the breed of ewe suckled. Beyond this stage, lactation potential of the ewe replaced demand by the lamb as the first limiting factor.Food intake by ewes during the first 6 weeks differed slightly with both ewe and lamb breed but there were larger differences associated with number of lambs suckled.The data suggest that lambs on higher milk intake consume a smaller proportion of solid feed but that, in all groups, live weight at 14 weeks of age was closely related to milk intake.