The effects of pH, osmolarity and urine contamination on equine spermatozoal motility

Urospermia has been reported as a cause of infertility in numerous species. The detrimental effects of urine on spermatozoa are due, at least in part, to changes in pH and osmolarity. Semen was collected and subjected to cond itions of varying pH (Experiment 1), of varying osmolarity (Experiment 2), and various quantities and concentrations of urine (Experiment 3) and effec ts on motility were recorded. Finally, semen was contaminated with urine an d then either of 2 semen extenders was added, with or without centrifugatio n, in an attempt to alleviate the detrimental effect of urine on motility ( Experiment 4). The results of these experiments showed that alterations in pH and osmolarity negatively affected stallion sperm motility, Optimal pH a nd osmolarity appeared to be approximately 7.7 and 315, respectively. Conta mination of the ejaculate with urine significantly decreased sperm motility . Smaller quantities of dilute urine were less detrimental than larger quan tities of dilute urine, and dilute urine was less detrimental than more con centrated urine. The addition of semen extender restored the motility of ur ine contaminated semen to that of the uncontaminated control, however centr ifugation to remove urine provided no significant advantage. (C) 2001 by El sevier Science Inc.