AbstractsBiology & Animal Science

The purpose of this thesis is to determine if dietary and metabolic relationships exist between cobalt and selenium. Two groups of lambs were compared. The dams of one group of lambs received an alfalfa hay adequate in selenium and the dams of the other group received an alfalfa hay deficient in selenium. At six weeks of age the lambs were sacrificed and examined for lesions of white muscle disease. The heart, liver, kidney, and skeletal muscle were analyzed for cobalt and selenium. The lambs in the low selenium group had a much lower concentration of this element in these tissues and organs than lambs fed the normal selenium hay. There was no difference in selenium concentration of tissues and organs between low selenium lambs with lesions of white muscle disease and healthy low selenium lambs. The cobalt concentration of tissues was unaffected by selenium intake, but when symptoms of white muscle disease appeared, the cobalt concentration of the kidney was significantly lowered. In a second experiment, groups of weanling rats were fed a basal diet deficient in selenium. One group received a selenium supplement, a second group received a cobalt supplement, a third group received both the selenium and cobalt supplements, and a fourth group served as controls. Rats from these groups were injected with selenium-75 (as selenite) and cobalt-60 (as cobaltous chloride) and the effect of dietary treatments on the uptake of the radiotracers by various organs was determined. Dietary selenium did not affect the uptake of cobalt-60, while dietary cobalt did increase the uptake of selenium-75 in the muscle (significant at the 90% level).