Abstract:
Animal production in Australia THE PRODUCTIVITY AND SELENIUM STATUS OF WEANER SHEEP SUPPLEMENTED WITH SELENIUM AND VITAMIN E DURING SUMMER D.W. PETER* and R.A. HUNTER* It is now evident that lambs and young sheep in low selenium (Se) regions in Australia may suffer from subclinical Se deficiency, i.e., appear healthy but show improved production following Se supplementation (McDonald 1975; Peter 1980), and that there are other factors beside Se involved in outbreaks of white muscle disease (Gabbedy et al. 1977). Since vitamin E and Se are complementary in action and the vitamin E intake of sheep grazing dry summer pastures may be low, the effects of selenium and vitamin E supplementation on the selenium status, live weight and wool production of weaner sheep during summer/autumn on a property in south-western Western Australia were investigated. Sixty Corriedale lambs were divided into three equal groups (A, B and C) at weaning in October. Animals in groups B and C received 1 mg Se by injection at weaning and three weeks later, after all animals were shorn, were given an intra-ruminal Se pellet ('Permasel', TVL Aust. Pty. Ltd.). Group C animals also received intra-muscular injections containing 1000 IU of a-tocopherol acetate in an oil base ('Forte', Hardocks Pty. Ltd.) at 14-day intervals throughout. Animals were weighed and blood samples collected at monthly intervals until June when animals were shorn and greasy fleece weights recorded. TABLE 1 Se concentrations in plasma and plucked pasture NO overt signs of Se deficiency were observed nor were there any effects of treatment on either live weight or wool production. All animals lost weight during summer with positive gains overall from November to June of 5.0 5 0.6, 5.5 +0.6 and 4.8 + 0.7 kg (mean + SE) for groups A, B and C respectively. Selenium concentrations in untreated animals were however within the reported range of animals with either white muscle disease or which showed improved production following Se supplementation. Therefore it appears that factors other than selenium may be involved in the occurrence of subclinical as well as clinical Se-deficiency. Because of the availability of green pasture in most months it is unlikely that the vitamin E intake of the animals in this trial was limiting. Further studies involving the vitamin E/selenium nutrition of weaners during summer are required. GABBEDY, B-J., MASTERS, H., and BODDINGTON, E-B. (1977). MCDONALD, J.W. (197%. Aust. Vet.-Z J. 51: 433. (in press). 53: Aust. Vet. J, C 482. PETER, D.W. (1980). Aust. J. Agric. Res. *CSIRO, Division of Animal Production, Wembley, W.A. 452 6014. --.
