INFLUENCE OF METFORMIN ON GROWTH DYNAMICS, SEMEN QUALITY, AND BLOOD TESTOSTERONE LEVELS OF RABBIT BUCKS REARED IN HOT TROPICAL CONDITION OF SOUTHEASTERN NIGERIA

Heat stress is one of the environmental factors that affect rabbit health and reproduction.Therefore, inexpensive methods to enhance sperm production and functions in heat-stressed rabbits have gained attention.One of these methods involved the use of metformin, that has proven antioxidant properties, to mitigate the negative consequences of heat-induced oxidative stress in rabbits reared in hot tropical conditions of Nigeria was investigated.Thirty-six rabbit bucks aged 10 to 12 months were divided into 3 groups (CD1, CD2, and CD0), with each group having 12 rabbits with three replications in a completely randomized design (CRD).Rabbits in the CD1 group were given metformin at 12.5 mg/kg body weight (BW) once daily for 5 days, while those in the CD2 group received metformin at 12.5 mg/kg BW twice daily for 5 days.Rabbits in the CD0 group served as the control and received normal saline for the same period.Semen and blood samples were collected from one rabbit in each replicate at the end of the experiment and analyzed statistically.Results revealed that feed intake, feed conversion ratio (FCR), and body weight gain (BWG) of rabbits exposed to heat stress were not affected by metformin administration.However, sperm motility and active motile cells were enhanced by metformin in the CD2 group.Likewise, sperm with abnormal morphology (big head, headless, pin head, and bent neck) were significantly lower in the CD1 and CD2 than in the CD0 group.In contrast, rabbits in the CD0 group produced sperm with shorter tails than those in the CD1 and CD2 groups.Results also showed significantly increased serum testosterone in the CD1 and CD2 than in the CD0 group.It is concluded that metformin at 12.5 mg/kg BW twice daily for 5 days improved serum testosterone, sperm motility, and active motile sperm cells and reduced the production of sperm with abnormal morphology in rabbits reared in hot tropical conditions of Nigeria.