The rôle of the breed of dam and of the breed of lamb in determining the copper status of the lamb. 1. Under a dietary regime low in copper

Abstract

ABSTRACTThe relative importance of the breed of lamb and the breed of dam in determining the copper status of the lamb until 24 weeks of age was investigated by transferring embryos within and reciprocally between Scottish Blackface and Welsh Mountain ewes. A diet low in Cu (2·4 mg/kg dry matter (DM) was fed both to the ewes from mating onward and subsequently to their lambs.At birth, lambs with Welsh dams had greater concentrations of Cu in their livers than lambs with Blackface dams. This difference, although reduced, still remained at 9 weeks of age (weaning), when lambs with Welsh dams also had greater concentrations of Cu in plasma.By 24 weeks of age, Welsh lambs, irrespective of their dams' breed, had greater concentrations of Cu in both liver and plasma than Blackface lambs, although the average Cu concentration in the liver was below 10 mg/kg DM in both breeds.Results are also given for concentrations of Cu in kidney, brain and milk.The experiment suggests the importance of maternal breed in determining the susceptibility, both of the foetus and of the young lamb to problems associated with Cu deficiency.