Abstract
To investigate a means for evaluating bull fertility, analysis of frozen-thawed bull sperm migration in the medium with or without bovine cervical mucus was carried out. Sperm were prepared by thawing frozen-semen from 4 bulls, which showed different conception rates of 71, 43, 43 and 1% by non-return rate post AI. Media with 50% cervical mucus and with 1% BSA were prepared to make a test column. A horizontal column of 21 cm length had specific shape and composition on a 60-mm Petri dish, and was used to analyze the migration characteristics of the sperm. After 2 h incubation, viability and migration of the sperm were examined. There was correlation between bull fertility and sperm migration in the media containing cervical mucus: the migration in the medium with cervical mucus of sperm from the bull with low fertility was lower than those of the other bulls with high fertility. After a single wash, the migration in medium without cervical mucus of sperm with high fertility was significantly higher than that of sperm with low fertility. The migration of sperm increased with the number of washes. This study confirmed that sperm viability after migration in a medium varied with different media used and was positively correlation with bull fertility in the medium containing cervical mucus. We concluded that the Petri dish-based horizontal column may be a useful tool for analyzing sperm migration as a predictor of bull fertility.
