Time Required for Spermatozoa to Remain in the Vagina of the Ewe to Ensure Conception

Abstract

Oestrous ewes (N = 202) were inseminated with O· I ml of semen containing 500 X 106 motile spermatozoa and the spermatozoa were flushed from their vaginae either immediately or 0'25, 0'5, I, 2, 4 and 8 h after insemination. Pregnancy was determined by returns to service and laparoscopy. Some ewes became pregnant (l0' 71 %) after spermatozoa had been flushed from the vagina only seconds after insemination and about 40% of ewes became pregnant after spermatozoa had been in the vagina for 15 min. Maximum conception (55%) was achieved when spermatozoa had been in the vagina for at least 2 h. It was concluded that the losses of spermatozoa that occur from the vagina will not influence the chance of a ewe conceiving because sufficient spermatozoa to ensure a normal conception move up the reproductive tract before large losses from the vagina take effect.