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U.S. Department of Agriculture, Beltsville, Maryland 20705
Abstract
Eight ewes in each of four groups were injected subcutaneously immediately prior to natural mating with 0, 30, 150, or 750 µg of estradiol-17ß. The ewes were necropsied 3 days after mating and the ova were examined. None of the three doses of estradiol reduced ovum fertilization significantly, but the 750-µg dose decreased the number of accessory sperm cells in the zonae pellucidae. Eight other ewes in each of four groups were treated with the same doses of estradiol-17ß and necropsied 25 days later. None of the estradiol treatments significantly reduced the rate of pregnancy.
The results indicated that doses of 30 or 150 µg of estradiol, injected immediately prior to mating, were not detrimental to sperm transport, ovum fertilization, or embryo survival for 25 days. The dose of 750 µg of estradiol may have reduced the efficiency of sperm transport.
1 Reproduction Laboratory, Animal Physiology and Genetics Institute, Agricultural Research Center.
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