Abstract
This study examined differences in the penetration of various batches of mixed cervical mucus by bull spermatozoa. Mucus was collected from different numbers (2, 2, 3, 4 or 7) of cows or heifers in estrus and a part of the sample was individually, and the rest was mixed, and stored frozen. The distance traveled by the most advanced sperm cell in frozen-thawed mucus during incubation at 38 C for 10 min was measured (sperm penetration). Variation of sperm penetration in the individual mucus samples was reduced by mixing but the difference among the batches of mixed mucus was significant (p<0.0002). Nevertheless, the number of animals from which mucus was collected and mixed did not seem to influence the sperm penetration of the different batches. Unexpectedly it was observed that some individual and mixed mucus samples had reduced viscosity after freezing and thawing and sperm penetration in the mixed mucus samples showed a significant, negative correlation with the proportion of mucus of reduced viscosity contained in the batch (r=-0.969, p<0.01). These results suggest that the difference in the sperm penetration of mixed mucus may probably be rather independent of the number of mucus donors.
