Comparative aspects of copper metabolism in sheep and deer (Cervus elaphus)

Ten yearling red deer stags (Cervus elaphus) and ten yearling Coopwerth wether sheep were offered ryegrass-white clover silage in amounts close to maintenance energy requirement. For six of each species, the diet was enhanced with 4.8 mg Mo and 2.4 g S/kg DM. Liver biopsy samples were obtained during weeks 1, 6, and 12. Five of each species were then offered the basal diet and the remainder, the basal diet supplemented with 4 mg Cu/kg DM. Liver biopsy samples were taken four and a half weeks later. Plasma samples were taken weekly for analysis of total and trichloroacetic acid (TCA) soluble copper. The mean initial liver copper concentration in sheep was 11- fold greater than in deer. Both diets induced liver copper depletion, and there was a trend for a greater rate of depletion on the Mo-S enhanced silage. The rate of depletion was 7-fold greater in sheep than in deer. In both species, highly significant linear relationships were observed between initial liver copper concentration and rate of liver copper depletion. During copper repletion, the rate of increase in liver copper in the supplemented groups tended to be greater in sheep than in deer. The mean estimate of endogenous loss of copper LW/d) was 1.43 ± 0.39 and 8.35 ± 1.71 in deer respectively. Calculated minimum values for availability of copper were 0.061 and 0.037 for deer respectively. (ug Cu/kg and sheep, fractional sheep and A TCA insoluble plasma copper fraction appeared toward the end of the depletion phase in sheep but not in deer. This fraction disappeared rapidly during repletion