Effect of season on sperm oestrual-mucus penetration in buffaloes

Abstract

The study was conducted to understand the effect of season on sperm oestrualmucus interaction in buffaloes through in vitro sperm penetration test in summer (n=35) and winter (n=55). The oestrual mucus was collected at the time of AI by recto-vaginal method. Sperm penetration tests (SPT) and biochemical analysis of oestrual mucus were performed to establish its relation with sperm-penetration distance (SPD). The in vitro SPD differed significantly between the 2 .seasons (21.22±1.08 mm/20 min in summer vs 32.67±1.28 mm/1.28 mm/20 min in winter). Biochemical studies of oestrual mucus revealed significantly higher contents of Na, Cl, Cu and Mn during winter than that in summer whereas pH was lower in winter. The K, Ca, Mg and Zn contents of mucus varied nonsignificantly between the 2 seasons. The SPD values were significantly correlated with oestrual mucus levels of Na, Cl, Ca and Mg during winter. A similar correlation was observed between SPD value and levels ofNa and Cl in summer. Significantly low conceptions occurred during summer than that in winter. The buffaloes that conceived during winter and summer had significantly different concentration of Na, Cl (higher) and Ca (lower) in their oestrual mucus than those failed to conceive. The Kconcentration was lower and Mg, Cu, Zn and Mn were higher in oestrual mucus of conceived buffaloes. From the present study, it was concluded that season influenced certain biochemical constituents of oestrual mucus, thereby, altering sperm mucus penetration and resulting in poor conception during summer.