184 Effect of breeding season on testicular morphometrics, spermatogenesis, and sperm quality in sheep.

Abstract Reproductive efficiency in rams is influenced by seasonal variations. The aim was to investigate the effects of the breeding versus the non-breeding season on testicular morphometrics, sperm quality, and testicular histopathology in sheep. A total of 28 testicles were collected from slaughtered rams during two different seasons: namely, breeding (September to November, n=10) and non-breeding (July to August, n= 18). Testicular morphometric parameters, including testicular and epididymal weights and lengths were recorded. Epididymal spermatozoa were recovered and evaluated for their motility (by CASA), viability and abnormalities (by eosin-nigrosin), and membrane integrities (using hypo-osmotic swelling test; HOS). Sections from testicles and epididymides were also prepared for histopathological examination. Data were analyzed by student t-test and Chi-Square test. Results showed that testicular and epididymal wights and lengths were higher (P< 0.05) in breeding than in non-breeding seasons. Sperm motility was higher (P< 0.05) in the breeding than in non-breeding seasons (75.0% vs. 55.0%). Percentages of live spermatozoa and sperm with intact membrane (HOS+) were also higher (P< 0.05) in the samples collected during the breeding season than those retrieved in non-breeding Samples collected during breeding season had lower (P< 0.05) sperm abnormalities than those obtained during the non-breeding season. Histopathological analysis revealed that 100% of of the samples collected during the breeding season exhibited moderate to normal spermatogenesis, however, 22% of the samples collected during the non-breeding season showed poor or arrested spermatogenesis with reduced or absent sperm storage indicating degeneration in the seminiferous tubules of the testicles. These findings confirm that rams experience significant seasonal changes in testicular function, sperm production, and sperm quality. Testicular and epididymal growth peak during the breeding season, while spermatogenesis and sperm motility decline in the non-breeding season. The data suggest that rams exhibit seasonal reproductive adaptations, with some experiencing temporary infertility in the non-breeding months due to lower motility, decreased viability, and increased abnormalities. These results provide valuable insights for optimizing breeding management strategies in sheep production.