Weight responses of sheep to cobalt and selenium in relation to vitamin B₁₂ and selenium concentrations in liver and kidney

Abstract

Weight responses to both cobalt and selenium supplements were obtained when young sheep were grazed alternately on paddocks representative of the soil types Kopua silt loam and Dannevirke silt loam. The selenium response, although statistically significant, was small compared with that due to cobalt.

Weight responses showed no cobalt and selenium interaction. There was no evidence that vitamin B₁₂ concentrations in liver or kidney were affected by selenium dosing (or selenium responsiveness) or that cobalt dosing (or cobalt deficiency) had an effect on selenium concentrations in liver. On the other hand, cobalt-deficient sheep, on an average, accumulated significantly more selenium in their kidneys than did those in which cobalt deficiency had been prevented.

The small and possibly intermittent selenium weight response was associated with an average selenium concentration in pasture of 0.048 µ/g on a dry-weight basis (range 0.037–0.067 µ/g).

Present results suggest that selenium levels in liver are likely to have greater diagnostic value than levels in kidney. The mean of selenium concentrations in the livers of selenium-responsive sheep was 0.12 µ/g on a wet-weight basis.