Abstract
Five ejaculates were collected from each of three draft horse stallions. Gel-free semen was diluted with a skim milk (SM) and egg yolk extender (EY) to have a final concentration of 25% seminal plasma. In addition, diluted samples were centrifuged and resuspended with the correspDnding extender (5% seminal plasma). Samples were filled in loosely capped testtubes (4.5 ml) and stored for 72 h at +20°C or +5°C. The percentage of progressively motile spermatozoa was examined subjectively at 0 h, 24 h, 48 h and 72 h. There was no significant difference in the percentage of progressively motile spermatozoa at 0 h in semen samples diluted with either SM or EY (66% and 67%, respectively). When semen samples were stored at +20°C, spermatozoal motility was in the range of 15%-33% after 24 h and below 20% after 48 h and 72 h. Storage of diluted semen samples at +5°C preserved spermatozoal motilityconsiderably better than at +20°C. After 24 h, the percentage of progressively motile spermatozoa was in the range of 35% (SM, 25% seminal plasma) to 50% (EY, 5% seminal plasma). The combination of EY and 5% seminal plasma (centrifugation) was superior to all other treatments in preserving spermatozoal motility up to 72 h.
