VITAMIN-E TREATMENT OF WEANER SHEEP .1. THE EFFECT OF VITAMIN-E SUPPLEMENTS ON PLASMA ALPHA-TROCOPHEROL CONCENTRATIONS, LIVEWEIGHT, AND WOOL PRODUCTION IN PENNED OR GRAZING SHEEP

Vitamin E supplements were investigated in terms of their effect on li veweight and wool production, and their effectiveness in increasing pl asma alpha-tocopherol concentrations and preventing nutritional myopat hy. In the first pare of the study in both pen and grazing experiments , commercially available preparations were compared. In a pen experime nt, 3 different treatments, intramuscular oily injection, oral drench, and dried supplement added to feed, were compared, and in grazing she ep, an intramuscular oily injection and the oral drench were compared. The intramuscular oily injection was slow to increase the plasma conc entrations of alpha-tocopherol in the pen experiment and did not preve nt deficiency of vitamin E and the development of subclinical myopathy in grazing experiments. Both oral treatments increased the plasma alp ha-tocopherol concentrations in the pen experiment, and although the r epeated oral drench did not increase the plasma alpha-tocopherol conce ntrations in the grazing experiment, the treatment prevented the devel opment of subclinical nutritional myopathy. In the second part of the study, experimental treatments of aqueous preparations of vitamin E an d the effect of selenium supplements were tested in grazing sheep. Aqu eous injections of 2000 mg of vitamin E acetate by intramuscular and s ubcutaneous routes in December and February were successful in both ra pidly increasing and maintaining plasma alpha-tocopherol concentration s in grazing weaner sheep. Injections of aqueous emulsions of vitamin E acetate could be the most useful preventative treatment for nutritio nal myopathy if problems of tissue damage can be overcome. None of the vitamin E supplements increased liveweight gain in any of the experim ents, and there was no increase in wool quantity or quality in any of the grazing experiments. When selenium and vitamin E supplementation w ere compared, selenium-supplemented sheep had greater wool length and fibre diameter over summer-autumn than vitamin E treated or control sh eep. Vitamin E supplements are costly, so unless particular flocks are susceptible to vitamin E responsive myopathy, this study suggests tha t there is little economic justification for using vitamin E as a supp lement over the summer.