Effect of Cobalt Applications to Pasture on Herbage Digestibility

Abstract

THE importance and essential role of vitamin B₁₂ and cobalt, its precursor, in ruminant nutrition and metabolism have been described^1–3. Cobalt deficiency in sheep results in marked changes in the rumen microflora⁴, and although some difference in the efficiency of fibre digestion may thus be expected to follow, there is little evidence to support this. Marston et al.² state that the rate and course of carbohydrate fermentation are unaffected by low cobalt levels in the rumen. Other workers have reported that cobalt supplements increased the digestibility of fibre^5,6, while Becker and Smith⁷ found fibre digestibility to be reduced by cobalt supplementation, although the digestibility of ether extract and nitrogen-free extract increased.