Objective measurement of sperm motility based upon sperm penetration of Accudenz.

When a suspension of rooster sperm was overlaid upon 6% (wt/vol) Accudenz, immotile sperm did not enter but motile sperm entered rapidly. The absorbance of the Accudenz layer increased as a result. These phenomena were used to measure sperm motility objectively at body temperature. The intra-assay coefficient of variation (CV) was 2.6% (n = 3). When roosters (n = 36) were ejaculated repeatedly and sperm motility data analyzed by two-way ANOVA, a male effect was observed (P < or = 0.001). When roosters were ranked by mean motility scores (n = 3 evaluations per male) and representative males selected as semen donors, a difference in fertility (P < or = 0.001) was observed between males characterized by minimal and maximal sperm motility. Frequency analysis with data from a second flock of roosters (n = 100) revealed a normal distribution. Roosters categorized by average sperm motility (n = 18) or sperm motility greater than one standard deviation above the mean (n = 17) were selected for further analysis by repeated measurements. A split-plot ANOVA revealed a difference between categories (P < or = 0.0001) and variation among males within a category (P < or = 0.0001). In contrast, sperm motility was independent of time and there was no interaction between category and time. Thereafter, five roosters from each group were ejaculated weekly and interassay CV estimated with semen pooled by category (n = 3 observations per category). During this interval, sperm motility of average roosters was 55 +/- 5.9% of that of roosters within the high motility category. Interassay CV were 18.1 and 9.2% for roosters originally categorized by average and high sperm motility, respectively. The assay described has potential for: 1) selecting males based on sperm motility, and 2) standardizing the measurement of poultry sperm motility.