Vitamin B ₁₂ and cobalt in livers from grazing cobalt‐deficient lambs and from others given Various Cobalt Supplements

Abstract

Summary Vitamin B 12 and cobalt concentrations were determined in the livers of 4 groups of lambs. Three groups were grazed on cobalt‐deficient pastures. Of these groups one received no cobalt treatment and developed marked cobalt deficiency disease. Of the other two groups on cobalt‐deficient pastures, one received oral doses of cobalt and the other cobaltic oxide pellets. The fourth group was grazed on cobalttopdressed pastures. Vitamin B 12 concentrations in the livers of markedly cobalt‐deficient lambs ranged from 0.026 to 0.097 μg/g of wet tissue, with a mean of 0.062 μg/g. Cobalt dosing and cobaltic oxide pellets increased liver vitamin B 12 concentrations about fourfold and sevenfold respectively. Vitamin B 12 concentrations in the livers of animals from cobalt‐top‐dressed pasture were of an order similar to those for lambs given cobaltic oxide pellets. Effects of cobalt deficiency disease and of cobalt treatments on B 12 Co/total Co ratios are discussed. From all the information available it is concluded that vitamin B 12 concentrations should provide a more sensitive indication of the presence or absence of cobalt deficiency disease than do cobalt concentrations. For sheep a value of 0.20 μg/g is suggested as an approximation to the minimal liver vitamin B 12 concentration (“critical level”) consistently associated with freedom from cobalt deficiency disease. Tentative vitamin B 12 diagnostic criteria are given.