PSII-A-2 Correlations between Reactive Oxygen Species and Functional Measurements of Spermatozoa from Beef Bulls

Reactive oxygen species (ROS) have effects on characteristics of spermatozoa, including mitochondrial membrane potential, acrosomal integrity, and structural abnormalities that can influence spermatozoa function. The objective was to determine correlations between sperm response to ROS and functional sperm measurements using ejaculates collected as part of bull breeding soundness exams (BSE). Semen samples were collected from Angus and Charolais bulls (403 ± 11 d of age; n=46) over three days during yearling BSEs. A veterinarian evaluated spermatozoa for percent motility and normal morphology, and percentage progressive motility was measured using an iSperm® analyzer. If ejaculates met minimum thresholds for passing a BSE, they were diluted to 70 million cells/mL using BoviFree® and sent overnight for flow cytometry evaluation. Flow cytometry assays including acrosome and cell membrane integrity, mitochondrial energy potential, and oxidation status. Data were analyzed using Pearson’s correlation coefficients in SAS. Percentage live spermatozoa with positive ROS status was correlated (r = 0.53; P < 0.001) with percentage progressive motility. Percentage live spermatozoa with negative ROS status was moderately correlated with percentage spermatozoa exhibiting secondary abnormalities (r = 0.33; P = 0.02) and tended to be lowly correlated (r = 0.28; P = 0.06) with percentage spermatozoa exhibiting primary abnormalities. Percentage live spermatozoa that had disrupted acrosomes was strongly correlated (r = 0.66; P < 0.001) with percentage live spermatozoa with negative ROS and also moderately negatively correlated (r = -0.31; P = 0.04) with percentage live spermatozoa with positive ROS. Percentage live spermatozoa with positive ROS status was correlated (r = 0.58; P < 0.001) with percentage of spermatozoa with active mitochondrial membranes. Live spermatozoa with positive ROS were strongly correlated (P< 0.001) with live spermatozoa (r=0.94) and live spermatozoa with intact acrosome (r=0.92). These data confirm previous research that shows the detrimental effects of ROS on spermatozoa function.