Effect of Cobaltic Oxide Pellets on the Vitamin B₁₂ Content of Ewes' Milk

Abstract

EVIDENCE that the provision of cobalt-containing supplements to ruminants will increase the vitamin B₁₂ content of their milk is conflicting. Harper et al. ¹ and Moinuddin et al. ² found that cobaltized mineral mixtures given to ewes fed on dry rations significantly increased vitamin B₁₂ levels in the milk. Other workers³, however, have reported that supplementary feeding with cobalt-containing trace element mixtures had no effect on the vitamin B₁₂ content of cows' milk when the animals were either stall-fed or grazed on pasture. According to Shrimpton and Duckworth⁴ extra cobalt given to grazing ewes either as a drench or in a mineral supplement failed to increase the vitamin B₁₂ content of the milk; but it seems doubtful whether any response would have been expected under the particular conditions of their trials.