Survival of spermatozoa in the genital tract of the mare

With insemination of approximately 2 billion sperms, pregnancy resulted from inseminations up to 6 days prior to ovulation, but not when inseminations were made earlier, or on the day after ovulation. 2. Ovulation was induced in one mare by injecting pregnancy urine extract when a large follicle was present in one ovary, although the mare remained anoestrous, as judged by vaginal and cervical secretions. This mare became pregnant from an insemination 2 days prior to the induced ovulation.