Testicular Morphometry and Histological Changes in Rabbit Bucks Fed Cottonseed Cake-Based Diets Supplemented with Vitamin E

Sixty-four(64) weanling rabbit bucks, aged 5-6 weeks and averagely weighing 511.98g, were randomly allocated to eight treatment combinations comprising four levels (0, 5, 10 and 15%) of cottonseed cake (CSC) and two levels (0, 30mg / kg diet) of vitamin E supplementation with eight replicates in a 2x4 factorial experiment. Animals were fed the treatment diets for a total of 20 weeks. At the end of the feeding trial, 3 rabbits per treatment were slaughtered and their reproductive organs carefully dissected out; separated into different components and measured. Left testis was fixed in Bouin’s fixative and later processed for histological assessment. Data on testicular morphometry were analyzed by ANOVA using the General Linear Model (GLM) appropriate for a 2 x 4 factorial experiment. Paired testis weight was significantly (P < 0.05) affected by the interaction of CSC and vitamin E supplementation. Paired testis length, paired testis width and paired testis volume were not significantly (P > 0.05) influenced by the CSC and vitamin E interaction. Paired epididymal weight was not significantly (P > 0.05) affected by the interaction. However, at 0% CSC, paired epididymal length was significantly (P < 0.05) smaller for the supplemented bucks than for the non-supplemented. The testes of bucks fed the control diet, both the supplemented and non-supplemented, did not show any histological alterations in the seminiferous tubules. There was normal spermatogenesis. Bucks that were fed 5, 10 and 15% CSC without vitamin E supplementation showed severe erosion and degeneration of germinal epithelium of the seminiferous tubules. No mature and morphologically normal spermatozoa were noticeable. Supplementing CSC-based diets with vitamin E corrected the degeneration caused by the CSC diets to the seminiferous tubules. It was concluded that prolonged feeding of CSC to rabbit bucks had deleterious effect on the testicular histology and consequently on spermatogenesis. However, vitamin E supplementation countered the adverse effect of the CSC. Rabbit bucks intended for breeding should not be fed CSC unless adequately supplemented with vitamin E.