[The optimal selenium supplementation in reproducing sows]

In two trials with sows of German Landrace at different dietary selenium levels glutathione peroxidase activity (GSH-Px activity) in plasma was determined at day 60, 90 and 110 of gestation, day 5, 15 and 25 of lactation and day 7 post weaning. In three groups of five first-litter gilts receiving 0.1, 0.3 and 0.5 mg selenium per kg diet, GSH-Px activities dropped within the treatments, independent of dietary selenium, from day 60 of gestation to a minimum at day 5 and 15, respectively, of lactation and increased again after weaning. Highest enzyme activities were observed at the 0.5 level. In another trial, 127 reproductive cycles of sows in first, second and third parity, respectively, with 0.1, 0.5 and 0.9 mg dietary selenium were investigated. GSH-Px activity showed results comparable to those of the former trial. Selenium content of plasma increased linearly as dietary selenium increased. In all cases, results of GSH-Px activity and of plasma selenium were confirmed by regression analysis. Reproductive performance ameliorated with increasing dietary selenium. Especially piglet's gain from birth to weaning and litter weight at weaning increased significantly. Furthermore, percentage of still born piglets showed a minimum at the selenium supplementation of 0.5 mg/kg diet. The pattern of GSH-Px activity in plasma and the improved reproductive performance of animals imply that the requirement of the sow during the reproductive cycle is met a level of 0.5 mg selenium per kilogram diet.