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Vitamin B 12 , in the blood of grazing cobalt-deficient sheep

1966; Taylor & Francis; Volume: 9; Issue: 3 Linguagem: Inglês

10.1080/00288233.1966.10431545

1175-8775

E.D. Andrews, B. J. Stephenson,

Reproductive Physiology in Livestock

Abstract Ewes grazing cobalt-deficient pastures were given cobaltic oxide pellets (cobalt “bullets”) 23 weeks before lambing commenced. At intervals, blood samples, for vitamin B12 assay, were taken from groups of untreated and treated ewes, and later, from groups or subgroups of untreated lambs from treated or untreated ewes, and from sub-groups of lambs given cobalt bullets directly. Also, livers and kidneys of lambs that died at or near to birth were assayed for vitamin B12. Cobalt treatment of ewes resulted in markedly increased vitamin B12 concentrations in the livers and kidneys of newborn lambs. However, although cobalt treatment of the ewes ameliorated, or delayed, the onset of cobalt deficiency disease in their lambs, the disease among the latter developed five weeks before weaning, that is, by the time the lambs were three to four months old. Treatment with cobalt bullets greatly increased vitamin B12 concentrations in the sera of ewes and lambs. At what appeared to be incipient stages of cobalt deficiency the disease was associated with mean serum B12 values of 0.26 mμg per ml for ewes, and of 0.30 mμg per ml for lambs. Thereafter, mean figures fluctuated widely from time to time, and at some subsequent stages exceeded those associated with incipient deficiency. However, at or towards the end of the respective experimental periods, when the effects of the disease had become marked in ewes and acute in lambs, mean B12 concentrations in sera in both cases fell to levels of <0.20 mμg per ml.