Seasonal variations in certain physical and biochemical attributes of semen from Cholistani bulls

In the present study, effects of stress-free and stressful seasons on certain physical and biochemical attributes of semen of Cholistani AI bulls were investigated. A total of 382 ejaculates from six bulls were collected at weekly intervals during four seasons viz. stress-free autumn (October-November), stressful winter (December-January), stressful dry summer (May-June) and stressful wet summer (July-August). These ejaculates were evaluated for various physical and biochemical attributes. Overall mean values (plus minus SEM) for ejaculatory volume, number of ejaculates per bull, mass motility, individual sperm motility, sperm concentration, number of doses of semen frozen per bull, percentages of live, morphologically normal sperm and those with intact acrosome were 4.92 plus minus 0.14 mL, 1.89 plus minus 0.02, 2.26 plus minus 0.06, 63.51 plus minus 1.03%, 989.73 plus minus 27.4 million/mL, 208.26 plus minus 8.42, 86.74 plus minus 0.55%, 86.34 plus minus 0.51% and 86.64 plus minus 0.48%, respectively. In general, all the parameters revealed significantly (P less than 0.05) better results in stressful seasons as compared to stress-free season. Overall mean values for Na+, K+, cholesterol and glucose in the seminal plasma were 102.79 plus minus 3.95 & 36.65 plus minus 0.99 mEq/L, 152.02 plus minus 3.17 & 127.22 plus minus 3.65 mg/dL, respectively. Amongst these, Na+ was higher (P less than 0.05) during dry summer, whereas K+ was higher in dry summer and winter. Cholesterol and glucose were elevated (P less than 0.05) during dry summer season. Correlation analysis revealed significant positive correlations between mass and individual sperm motility, morphologically normal and live sperm and sperm acrosome integrity and live sperm (P less than 0.01). Among biochemical attributes of seminal plasma, Na+ and K+, cholesterol and K+ and glucose and Na+ were correlated (P less than 0.01). Considering seminal plasma biochemical constituents and physical attributes, only seminal plasma cholesterol was positively correlated with ejaculatory volume (P less than 0.01). In conclusion, various physical and biochemical attributes of Cholistani bull semen were better in stressful seasons as compared to stress free season.