Seasonal variation in sperm characteristics, antioxidant defence systems, seminal plasma testosterone and total proteins of beetal bucks

Fourteen mature Beetal bucks were randomly selected and evaluated for sperm attributes, oxidative stress, antioxidant defence systems, seminal plasma testosterone and total protein during two major seasons (summer and winter) of the year 2018–19. It was observed that bucks responded differentially to summer and winter stresses. Sperm counts were significantly (P<0.05) higher during winter (2.6±0.2x109/ml) than summer (1.7±0.1x109/ml). Individual motility and viability were significantly (P<0.05) improved in winter (69.9±3.0% and 78.4±1.4%) as compared to summer (59.7±2.1% and 68.5±2.8%). Malondialdehyde and superoxide dismutase (SOD) were significantly (P<0.05) higher during summer compared to winter. There was positive correlation between lipid peroxidation (LPO) and all sperm attributes and only viability during summer and winter, respectively. SOD was negatively correlated with sperm attributes during both the seasons. The means for the activities of catalase (CAT) and glutathione reductase (GRE) were quite opposite to LPO and SOD i.e. higher during winter as compared to summer and suggested that SOD was not utilized by the spermatozoa to reduce oxidative stress in summer and in return sperm attributes remained low. The higher activity of CAT and GRE during winter acted in conjunction with SOD for its utilization by spermatozoa to reduce the oxidative stress and enhance the sperm function in winter. CAT and GRE were positively and negatively correlated with all sperm attributes except plasma membrane integrity (PMI), volume and initial motility, acrosome integrity during winter, respectively. But, the correlations were negative for all sperm attributes (catalase) and positive for all attributes except PMI (GRE) during winter. The mean testosterone and total proteins levels were significantly (P<0.05) higher during summer as compared to winter. It was concluded that season influenced the semen quality in Beetal bucks and it was in general, better in winter than in summer.