Influence of Yolk-Citrate, Yolk-Glycine, Whole Milk, and Skimmilk Extenders Containing Glycerol on Motility of Bovine Sperm at 37 and 5° C.

Sixteen semen samples were extended 1:50 in 14 extenders with 7.5% glycerol added by direct and step-wise procedures to give 28 different extender treatments. Aliquots of each treatment were stored at 37 C. for 12 hr. and at 5 C. for seven days. Yolk-2.9% citrate, yolk-2.0% citrate, yolk-2.9% glycine, whole milk, and skimmilk were the basic extenders, together with mixtures of these at 1 : 1 in all possible pair combinations. Direct glycerolation generally gave better results than stepwise, as evaluated by progressive sperm motility, but these effects were not significant by seven days of storage at 5 C. Independent of glycerolation method, progressive motility at 37 C. was significantly higher in yolk-2.9% citrate and its combinations than in yolk-2.0% citrate and its comblnations, but the reverse was true at 5 C. Extenders composed solely of milk constituents performed favorably at 5 C. and poorly with prolonged 37 C. storage. No single extender or combination of two basic extenders gave similar results, as time and temperature of storage and method of adding glycerol were varied.