title: The HOS test and its relationship to fertility in the stallion.
abstract: The hypo-osmotic test has been used successfully on equine semen and was considered to be a simple and accessible method which could be a useful addition to routine equine semen analysis. It was therefore of interest to determine whether the hypo-osmotic test is significantly correlated to proposed criteria of fertility. The stallions were divided into two groups on the basis of threshold levels of fertility. A significant difference (P<0.05) was found between the two groups for the following parameters: progressive motility, morphologically normal spermatozoa, percentage of swelling with the hypo-osmotic test, percentage of pregnant mares and number of services per pregnancy. The hypo-osmotic test provided a simple evaluation of membrane function and the results obtained show stallions with low swelling scores (<40%) to be of doubtful fertility. The hypo-osmotic test was not correlated with percentage of pregnant mares but showed a tendency to correlate with the number of services per pregnancy, therefore it could be an additional method for evaluating stallion fertility. Further studies are needed to confirm this observation.
authors.affiliation: Area of Theriogenology, Faculty of Veterinary Sciences, University of Buenos Aires, Argentina.
authors.forename: D M
authors.initials: DM
authors.lastname: Neild
authors.forename: M G
authors.initials: MG
authors.lastname: Chaves
authors.forename: M
authors.initials: M
authors.lastname: Flores
authors.forename: M H
authors.initials: MH
authors.lastname: Miragaya
authors.forename: E
authors.initials: E
authors.lastname: Gonzalez
authors.forename: A
authors.initials: A
authors.lastname: Agüero
mesh_terms: D000818:Animals; D005298:Fertility; D006736:Horses / Q000502:physiology*; D008297:Male; D009995:Osmosis; D013094:Spermatozoa / Q000502:physiology*