Effects of “marginal” deficiences of copper and selenium on growth and productivity of sheep

摘要

Abstract Six hundred 6–week–old Romney Marsh ewe lambs were individually allocated at random to one of four treatments and received (a) no treatment; (b) selenium (11.96 mg anhydrous sodium selenate); (c) copper (568 mg CuSO4.5H2O); or (d) copper plus selenium (as above), orally, at the commencement of the experiment, and at monthly intervals thereafter until the animals lambed at 2 years of age. At 11 months of age selenium–treated sheep were 9% heavier and clipped 12% more wool than untreated animals, and at 23 months of age they were 4% heavier and clipped 8% more wool. Fertility, as measured by barrenness in 2–year–old ewes, was unaffected by selenium therapy, but fecundity was significantly improved, the incidence of twinning being 8% higher in selenium–treated ewes. Significant (p<0.05) copper–selenium interactions occurred, in which live weight, fleece weight, and fecundity responses were induced by copper therapy, but only in selenium–treated sheep. At 11 months of age animals which had received b...