The present study was designed to investigate the efficacy of royal jelly (RJ) and propolis (P) on semen quality and fertility of New Zealand White (NZW) rabbit bucks, under Egyptian summer conditions. Thirty NZW rabbit bucks and 60 hybrid nonparous females were used in the present study. Rabbit bucks were randomly divided to 3 groups (10 bucks per group), bucks were administered orally with 0.5 mL of a solution/ kg body weight (BW), once weekly for 6 weeks; which contained: 1) water for control (C-group), 2) 400 mg royal jelly (RJ) dissolved in 0.25 mL water + 0.25 mL bee honey for (RJ-group), 3) 10 mg propolis (P) was suspended in 0.5 mL water for (P-group). The current study demonstrated that NZW rabbit bucks received either royal jelly or propolis showed significant (P<0.05) increase of reaction time, ejaculate volume, percentage of sperm progressive motility, sperm-cell concentration and seminal plasma fructose concentration compared to control group. On the other hand, percentages of dead and abnormal spermatozoa increased significantly (P<0.05) for control group compared to the other two groups. Blood plasma concentration of testosterone increased significantly (P<0.05) for both royal jelly and propolis treated bucks compared to Control. Otherwise, plasma concentrations of cholesterol, aspartate amino transferase (AST) and alanine amino transferase (ALT) were reduced significantly (P<0.05) for royal jell and propolis groups compared to control group. Rabbit bucks treated with either royal jelly or propolis showed better fertility (higher conception rate and litter size) than control bucks.
Conclusively, the results of the present study showed that royal jelly or propolis could be used beneficially to improve semen quality and fertility of rabbit bucks under Egyptian summer conditions. This improvement was also mirrored on better liver functions as observed with lower concentrations of AST and ALT.