Effect of vitamin E or propolis supplementation on semen quality, oxidative status and hemato-biochemical changes of rabbit bucks during hot season

This study was designed to determine the effects of supplementation of vitamin E or propolis to bucks’ diets on semen quality, oxidative status and hemato-biochemical changes during summer season. Thirty adult male New Zealand white rabbits were randomly allocated into three equal groups, 10 bucks each. Bucks received a maintenance diet supplemented by vitamin E (150 mg/kg diet, E-group) or propolis (150 mg/kg diet, P-group) or not supplemented (control, C-group) for ten consecutive weeks. Semen and blood samples were collected to analyze semen quality traits and hemato-biochemical parameters, respectively. Ambient temperature and relative humidity were recorded daily and used to estimate the temperature humidity index (THI). Results indicated that bucks in the E- and P-groups had better libido (lower reaction time, P<0.05) and higher sperm concentration and viability than the control group (P<0.01). These enhancements were parallel to an increase in blood plasma testosterone concentrations in the vitamin E and propolis-treated groups (P<0.01). Additionally, concentrations of seminal plasma total protein and initial fructose were significantly increased in the semen of both treated-groups. For blood components, either vitamin E or propolis supplementation enhanced hematopoiesis including the number of red blood cells, hematocrite value and hemoglobin concentration (P<0.01). Also, concentrations of blood plasma glucose and high density lipoprotein (HDL) were increased, while those of blood plasma cholesterol and triglycerides were decreased (P<0.01) in both treated-groups. Supplementation with vitamin E or propolis enhanced (P<0.01) oxidative status of the blood plasma, whereas propolis-treated bucks had the highest value of total antioxidant capacity followed by vitamin E treated-bucks. Also, malondialdehyde activity was lower (P<0.05) in the propolis-treated bucks compared with the control, while bucks of the E-group were intermediate. In summary, inclusion of vitamin E or propolis in male rabbits' diets during the hot season could be used effectively to mitigate negative impacts of elevated temperature on semen quality, oxidative status and hemato-biochemical features.