Effects of supplementation with vitamin E and selenium on the production of grazing weaner and hogget wethers

Abstract

hoc. Amt. Sot. Abm. Prod. 1994 Vol. 20 EFFECTS OF SUPPLEMENTATATION WITH VITAMIN E AND SELENIUM ON THE PRODUCTION OF GRAZING WEANER AND HOGGET WETHERS D.W. PETER, P. YOUNG and D.J. BUSCALL CSIRO Division of Animal Production, Private Bag, PO, Wembley, W.A. 6014 Although frank deficiencies of vitamin E (Vit E) can develop in sheep of adequate selenium (Se) status grazing dry feed (Steele et al. 1980) it is not known if marginal deficiencies of Vit E result in production losses similar to those which occur with Se. This was investigated over 2 years (1990/91; 1991/92) at Bakers Hill, Western Australia (WA), with wethers grazing pastures low in Se and also low in Vit E when dry. Four groups each of weaner and hogget wethers (n = 15/group) were grazed together and supplemented as follows: nil supplement (-Se/-E), or supplemented with Se alone (+Se/-E), with Vit E alone (-Se/+E) or both Se and Vit E (+Se/+E). Supplements were given orally by aqueous drench at 6 week intervals starting in December in both years. Se treatment (0.1 mg Se/kg liveweight as sodium selenite) continued until shearing in late September while Vit E treatment (100 mg Vit E/kg liveweight as RovomixE-20W'') ceased in June 1991 and May 1992. The sheep were fed lupin supplements during autumn. Greasy wool weight was recorded at shearing and a mid-side sample taken for determination of clean wool weight (CWW), fibre diameter (FD), staple length (SL) and staple strength (SS). Weaner sheep from 1990/91 were retained as ho gets in 1991/92 and combined with 4 groups of new weaner wethers. The most significant treatment effects of note occurred in 1990/91 since rain in February 1992 resulted in some green pasture during autumn in year 2; wool data from 1990/91 only are presented (Table 1). Weaner CWW in the -Se/-E group was lower in 1990/91 than in other treatment groups and associated with a significant Vit E x Se interaction (P < 0.05); FD and SS were not affected. These effects persisted in the hogget year, 1991/92, whereas in this year there were no effects of treatment on weaner CWW, FD or SS. Hogget CWW, FD or SL were not affected by treatment in 1990/91 but there was a highly significant Vit E x Se interaction with SS (P < 0.001). Se supplementation resulted in a higher SL in weaners in both years (P < 0.05). There was a significant Vit E x time interaction with liveweight in year 1990/91, with lower and higher liveweight gains in early spring after supplementation ceased in Vit E supplemented weaners (P c 0.05) and hoggets (P c 0.01) respectively. No effects of treatment on liveweight were observed in either age group in the second year. Table 1. Effects of Se and Vit E supplementation on clean wool weight (CWW), fibre diameter (FD), staple length (SL) and staple strength (SS) in 1990/91 (Mean with s.e.m. in parenthesis) The results suggest that marginal deficiencies of Vit E are unlikely to cause losses of production in grazing sheep provided their Se status is adequate. This work was supported in part by the WRDC. STEELE, P., PEET, R.L., SKIRROW. S, HOPKINSON, W. and MASTERS, H.G. (1980). Amt. Vet. J. 56: 529-32. 443