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The aim of the current study was to investigate the effects of injecting estrus-synchronized ewes with vitamin E and selenium (Se) on their reproductive performance. Awassi ewes (n = 74) were randomly assigned into one of two groups. Group one (control, n = 36) did not receive vitamin E/Se injections, and group two (vitamin E/Se, n = 38) received 13.6-mg/kg BW of vitamin E plus 0.045-mg/kg BW of Se. Concurrent with estrus-synchronization program, vitamin E/Se injections were given at the time of insertion, withdrawal, and 19 days after withdrawal of intravaginal sponges. At all injection times, serum samples were collected (20 ewes per group) to measure Se contents. Pregnancy rates were evaluated by progesterone assay and by ultrasonography, respectively, at days 19 and 40 after sponge removal. Lambing rate, singles and twins%, sex ratio (M:F), and birth weight were recorded at lambing. Vitamin E/Se injections did not affect (P 0.25) BW at lambing or BW change of ewes from breeding to lambing. Vitamin E/Se injections tended (P = 0.08) to decrease total pregnancy losses from 44.8 to 24.3%, subsequently, injections positively improved (P 0.05) pregnancy rates determined by progesterone assay (from 80.6 to 97.4%) and ultrasonography (from 63.9 to 86.8%). Although overall fertility was not affected, vitamin E/Se injections markedly increased the percentage of ewes that lambed after only one service from 64.0 to 93.3%. Singles and twins%, lamb sex ratio, and birth weight of lambs were not affected (P 0.20) by vitamin E/Se injections. Under conditions of our study, multiple injections of vitamin E/Se improved the reproductive performance of estrus-synchronized ewes. |
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