Effect of injecting 2- and 3-year-old ewes with selenium and selenium-vitamin E on reproduction and rearing of lambs

The experiment was conducted on 150 Polish Merino ewes divided into six groups. Three groups consisted of 2-year-old ewes, before their First lambing and three groups of the 3-year-old ewes after the first lambing. Within each age category, one group of ewes was treated with 5 ml 0.1% sodium selenate and 250 mg vitamin E while the third one was a control group. The effect of i.m. injection of Se and Se plus vitamin E on oestrus, fertility, prolificacy, number of lambs reared, the weight of lambs at birth and the live weight gain for 28 days was investigated. The blood plasma was sampled twice before injection, the mean Se concentration in 2-year-old ewes were 1.7 and 1.47 mumol l(-1) and in 3-year-old were 1.11 and 1.37 mumol l(-1), respectively. The corresponding values for vitamin E concentration were 3.47 and 5.73 mumol l(-1) in younger and 3.38 and 5.0 mumol l(-1) in older ewes. Two consecutive injections of Se (before mating and lambing) significantly (p < 0.05) increased incidence of oestrus (100%), fertility (100%, p < 0.01), lamb body weight at day 28 (10.9 kg, p < 0.01) and daily weight gain for 28 days (241.8 g, p < 0.01) in 3-year-old ewes compared with controls (76, 68%, 9.4 kg, 197.7 respectively). Administration of Se also significantly (p < 0.05) increased daily weight gain in first 4 weeks of life (220.1 g) in lambs of 2-year-old dams (186.1 g for controls), but decreased (p < 0.05) lamb live weight at birth (3.9 kg versus 4.3 kg in controls). In contrast, the injection of Se plus vitamin E did not significantly increase reproduction and rearing performance in 2- nor 3-year-old ewes. (C) 2002 Published by Elsevier Science B.V.