Abstract
The effects of caffeine on the motility of frozen-thawed bull spermatozoa from 4 different bulls and their ability to fertilize in vitro matured oocytes was assessed. Frozen-thawed semen was divided into two groups. One group was incubated for 6 h in BO solution either with or without 2.5 mM caffeine. During the incubation period, the motility for each bull was observed at 0.5 h intervals. The other group was used to inseminate in vitro matured bovine oocytes. The addition of caffeine to the BO solution did not stimulate the motility of all bulls. The percentage of embryos that cleaved by the third day after insemination varied between bulls. In one bull, the percentage of cleaved embryos was significantly lower (P<0.05) than for the other bulls in the presence of caffeine. This percentage was also significantly lower (P<0.05) than that in the absence of caffeine in the same bull. These results indicated that caffeine do not stimulate the motility of frozen-thawed bovine spermatozoa in the BO medium, and that caffeine is not necessarily useful for the induction of in vitro sperm capacitation.
