Selenium supplementation of grazing sheep. III. Effects of supplementation of ewes before and/or after lambing on the selenium status, blood enzyme activities and the growth of their lambs

Abstract

The effects of oral selenium administration to ewes during pregnancy and/or following parturition on ewe fertility, the selenium status of the ewes until lambing and of their lambs from birth to 70 days of age, on plasma enzyme activities and on lamb growth were investigated by using four groups of ewes grazing pasture in the low selenium region of New England. Selenium treatment prior to parturition resulted in significantly higher activities of erythrocyte glutathione peroxidase, i.e. a higher selenium status, of both the ewes and their lambs at lambing, though the selenium status of untreated ewes and their lambs was considered adequate. There were significant increases in the activities of erythrocyte glutathione peroxidase of lambs following selenium supplementation of their dams at parturition, whereas activities of lambs with untreated dams declined; depending on the selenium status of the dam, lambs received varying selenium supplements via milk. There were no significant effects of selenium treatment on ewe fertility or on the patterns of growth of the groups of lambs. However, from 49 days of age onwards, lambs whose dams received selenium at parturition were significantly heavier than lambs whose dams did not receive supplementary selenium. The results are discussed in relation to recommended schedules for oral selenium supplementation and the diagnosis of selenium inadequacy in grazing sheep.