An assessment of the effects of ruminal selenium pellets given to young sheep grazing selenium-deficient pastures

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Abstract
Extract The ability of a heavy pellet containing cobaltic oxide to release cobalt when lodged in the reticulo-rumen of the sheep was first described by Dewey et al. (1958) Dewey, D. W. , Lee, H. T. and Marston, H. R. 1958. Provision of cobalt to ruminants by means of heavy pellets. Nature, Lond., 181: 1367–1371. [Google Scholar] . However, investigation has shown that, at least in some situations, treatment with cobaltic oxide pellets may have two disadvantages. First, pellets may acquire a deposit of calcium phosphate, thus tending to seal the pellet off from the, reticulo-rumen environment (Andrews et al., 1958 Andrews, E. D. , Hartley, W. J. and Grant, A. B. 1968. Selenium-responsive diseases of animals in New Zealand. N.Z. vet. J., 16: 3–17. [Taylor & Francis Online] [Google Scholar] ; Dewey et al., 1958 Dewey, D. W. , Lee, H. T. and Marston, H. R. 1958. Provision of cobalt to ruminants by means of heavy pellets. Nature, Lond., 181: 1367–1371. [Google Scholar] ; Millar and Andrews, 1964 Drake, C. , Grant, A. B. and Hartley, W. J. 1960. Selenium and animal health. Part 2: The effect of selenium on unthrifty weaned lambs. N.Z. vet. J., 8: 4–10. [Taylor & Francis Online] [Google Scholar] ). Secondly, some sheep may eventually lose their pellets by regurgitation (Millar and Andrews, 1964 Watkinson, J. H. 1966. Fluorimetric determination of selenium in biological material with 2,3-diaminonaphthalene. Analyt. Chem., 38: 92–97. [Crossref], [PubMed], [Web of Science ®] [Google Scholar] ).