Influence of photoperiod on testicular activity in rams: Comparative reproductive, hormonal, and histological insights across seasons.

Background: The photo period has a great effect on the testicular efficiency of Rams, as it differs between breeding in comparison to, Non- Breeding periods. The male hormone also shows great variation according to the photo period. Aim: This study aimed to examine the seasonal variation in ram fertility (ultrasonographic, hormonal, histopathological). Methods: Throughout the breeding and non-breeding seasons, blood samples were collected weekly from the animals' jugular veins. On the same day as the measurement, 10 ml of blood from each animal was collected in Vacutainer tubes, and testosterone hormone, follicle stimulating hormone (FSH) , and leutinizing hormone (LH) concentrations were evaluated. Then, scrotal and testicular dimensions were recorded weekly. An ultrasound machine was used to image the testicles and epididymis of the ram in the standing position. For each animal, six representative fields were selected for morphometric analysis, and quantitative measurements were carried out. Results: The result dedicated to that season has a greater significant impact on testosterone levels and FSH and LH levels. A higher level of significant variation in testicular measurement was observed. The testicular parenchyma of both ram groups was uniformly echogenic (B-mode), but during the breeding season, the mediastinum testis was large in size and more clear compared to out of breeding. Ultrasonographic image of the tail of the epididymis. Appears to be enlarged and heterogeneous in the echotexture and less echogenic than the testis. Seminiferous tubules were lined with stratified epithelium, which comprised distinct phases of one row of spermatoic cells, huge primary and secondary smaller spermatocytes, and round spermatids clustered at the lumen of the tubules.Immunohistochemical studies showed that the androgen receptor antibody was expressed at the seminiferous tubules, particularly in Sertoli cells and myoid cells which appeared obviously in the breeding season. The immunoreaction for S-100 protein revealed strong S-100 expression in Sertoli cells, especially in their nuclei, which appeared darker in the breeding season. The strength of S100 protein immunoreactivity in Sertoli cells is somewhat reliant on the cyclical fluctuations of the seminiferous epithelium. Conclusion: The present study concluded that differences were evident in the hormonal profile, ultrasonographic findings, and histopathological characteristics of the tests, and this was associated with increased testicular activity and more active seminiferous tubules histologically in breeding season comparing to non-breeding seasons. These results confirm the strong seasonal influence on reproductive performance in rams.