Reversibility of the reproductive toxicity of gossypol in peripubertal bulls

Gossypol has been shown to impair sperm production in male ruminants. The purpose of this study was to determine if the adverse effects of gossypol on spermatogenesis in peripubertal bulls were reversible. Twenty-eight crossbred Angus bulls were allocated into treated and control groups at 11 months of age. For 8 weeks, treated bulls were fed a ration containing 8mg of free gossypol per kilogram of body weight per day while control bulls were fed a soybean meal ration free of gossypol. At 28-days intervals, scrotal circumference was measured and semen collected to assess sperm motility and morphology. Seven control and seven treated animals were castrated 56 days after the start of the experiment and the testes were examined histologically. The remaining bulls were fed a gossypol-free diet for 210 days prior to castration. There were significant increases in primary and secondary sperm abnormalities in treated bulls 28 and 56 days after gossypol feeding. The number of sperm with proximal droplets was significantly higher in gossypol-treated bulls, suggesting testicular degeneration. There was no significant effect on the sperm motility, scrotal circumference, or histopathological characteristics of the testes. Four weeks after the end of gossypol feeding, primary and secondary abnormalities were still increased in gossypol-treated bulls, however in subsequent collection periods the percentage of abnormalities were similar between groups. At 210 days, there was no treatment effect on scrotal circumference, and histological characteristics of the testes were not different between groups. The deleterious effects of gossypol on the morphological characteristics of spermatozoa were reversible. Gossypol (8mg/kg per day for 56 days) increased sperm abnormalities but the effects were reversible.