A total of 141 heifers and cows, predominantly Holsteins, was used to compare fertility of sperm entering and leaving the epididymis. Testicular and eauda epididymal sperm were obtained through indwelling cannulae while ejaculated sperm were collected before surgery on seven Holstein bulls. After deposition of 200 X 106 sperm in the uterine body, 106 females were killed on day 4 of a natural estrous cycle. Percentages of fertilized ova were 0% for testicular sperm, 84% for cauda epididyreal sperm, and 94% for ejaculated sperm. Fertilizing capacity of cauda epididymal and ejaculated sperm was not significantly different. In contrast to observations for the other sperm types, testicular sperm were not detected on ova recovered on day 4. Testicular sperm also were not associated with five other ova, or in oviduct flushings, recovered 12 to 14 h after uterine body inseminations. However, epididymal or ejaculated sperm were plentiful in ova and flushings from two cows killed 13 to 14 h after insemination. The infertility of testicular sperm may result from intrinsic factors, a failure of sperm transport into the oviducts, or unusually rapid elimination of testicular sperm from the oviducts.
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Amann et al. (1974) studied this question.
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