AUTOMATED-ANALYSIS OF STALLION SPERM MOTILITY AFTER THAWING

The quality of frozen stallion semen is evaluated after thawing by subjective estimation of the percentage of motile spermatozoa. When the mean % of motile spermatozoa of 3 straws from the same ejaculate is under 35 %, the ejaculate is rejected. The use of the Hamilton Thorn Motility Analyser (HTM) can be an objective mean to select frozen ejaculates. Establishment of correlations between the motility estimated by the INRA technician, and the characteristics of motility analysed by the HTM on the same ejaculates allowed us to test the reliability of the HTM measurements. The lack of correlations between the HTM characteristics of selected ejaculates and the fertility observed on the field, shows that the limit of acceptability of frozen semen (motility greater-than-or-equal-to 35 %) has selected a population of equal potential fertility. So the HTM wil be now << the eye of the technician >> for the selection of frozen semen of stallions from the National Studs.