Severe heat stress is recognized as a factor that severely influences the semen quality and antioxidant status of rabbits. In this context, fresh onion juice (FOJ) may be a safe and useful option to improve reproductive performance. This research was designed to evaluate the anti-stress effects of FOJ on physiological and semen parameters in heat-stressed bucks. Thirty-six V-line rabbit bucks were randomly distributed into three groups. The bucks received FOJ orally at different doses [0 (water), 1.5, and 3 ml/kg live body weight] every 2 days over a period of 2 months, with 3 weeks as an adaptation period. FOJ treatments significantly improved semen characteristics, such as libido, mass and individual sperm motility, semen concentration, sperm viability, and acrosome reaction with increased initial seminal fructose, via the oral administration of 1.5 and 3 mL FOJ/kg body weight, compared with the findings in control bucks. Seminal plasma antioxidant status was significantly enhanced by FOJ treatments. It was concluded that the oral administration of FOJ under severe heat stress can improve bucks' semen characteristics and sex hormone concentrations except for testosterone, and it is considered a good strategy for improving the heat resistance of rabbit bucks, possibly due to its antioxidant activity.
Keywords: Fresh onion juice; physiological parameter; rabbit; semen characteristic; sex hormone.