The fertility of stallions
Cutler, R.S.
Veterinary Record 94(3): 55
1974
ISSN/ISBN: 0042-4900 PMID: 4856261 Document Number: 77094
Semen samples taken from the penis of two aged stallions immediately after service contained 85% non-motile spermatozoa at the first covering of the season. Using the stallions at 2-day intervals, the number of non-motile spermatozoa dropped, and at the 4th to 6th covering it was often as low as 15%. In another two stallions (8-10 years old) the number of non-motile spermatozoa did not drop below 85%, and these stallions were largely infertile; one did fertilize a mare on a day when semen moltility was 25%. Some young stallions started their first season with 60% motile spermatozoa, and this figure increased over a fortnight (4-6 coverings) to 80%. In some experienced stallions the motility figure did not vary at all while in others it improved by about 10% in the early part of the season. Old stallions with a motility figure of 75% or more proved fertile.