Comparison of extenders and storage temperature in chilling canine semen

Abstract This study aimed to compare the effects a commercial milk-based extender and a self-made egg yolk extender had on the quality of canine semen stored at two different temperatures, 5ºC or 15ºC. The ejaculate obtained was split into two aliquots of equal volume and diluted with the milk or egg yolk extender. The final concentration was 100×106 spermatozoa/mL. Diluted semen was placed in transport containers and maintained at final storage temperatures of 5ºC and 15ºC. The quality of the chilled semen was assessed 12, 24, and 36 hours after storage. Semen diluted with the milk extender had higher motility, vigour, and plasma membrane integrity (p<0.05) of the spermatozoa than that diluted with the egg yolk extender. No difference in the semen quality was observed between the stored temperatures in both the groups. The difference observed between the extenders could be due to the standard formulation of the commercial milk extender and the presence of glucose in the mixture. In conclusion, the milk extender was better than the egg yolk extender at preserving the motility, viability, and membrane integrity of chilled canine semen for up to 36 hours. The storage temperature did not seem to affect the semen quality, suggesting that canine semen can be refrigerated at 15ºC.摘要 本研究旨在比较商用奶基稀释液与自制蛋黄稀释液对犬精液在5℃和15℃两种不同温度下储存后的品质影响。采集的精液被等分为两份体积相等的分样，分别以奶基或蛋黄稀释液进行稀释，最终精子浓度调整为100×10^6个/毫升。稀释后的精液被置于运输容器中，分别维持在5℃与15℃的最终储存温度。分别于储存后12、24、36小时评估低温保存精液的品质。结果显示，相较于蛋黄稀释液组，奶基稀释液组的精子运动率、运动强度及质膜完整性均显著更高（p<0.05）。两组的储存温度对精液品质均无显著影响。两种稀释液间的品质差异可能源于商用奶基稀释液的标准化配方及其混合物中葡萄糖的存在。综上，在长达36小时的低温保存周期内，奶基稀释液在维持犬精液的活力、活率及膜完整性方面均优于蛋黄稀释液。储存温度似乎对精液品质无显著影响，这表明犬精液可在15℃条件下进行冷藏保存。