Characteristics and seasonal variation in the semen of Markhoz bucks in western Iran

Abstract

The aims of the present study were to evaluate if seasonality in semen characteristics and plasma testosterone concentrations exist in Markhoz male goats. Ten Markhoz (Angora) bucks were housed and fed according to standard recognized practices. During the observation period, semen was collected monthly with the aid of an electro-ejaculator and examined microscopically immediately after collection. Physical parameters of semen and the semen index were recorded. Blood samples were also taken monthly throughout the observation period and the plasma testosterone concentration monitored. Bucks demonstrated a higher semen quality ( P < 0.05) in autumn and summer (semen index of 965 × 10 6 and 752 × 10 6 ml −1, respectively), compared to spring and winter (semen index of 606 × 10 6 and 512 × 10 6, respectively). This coincided with a higher ( P < 0.05) plasma testosterone concentration in autumn and summer (8.1 and 10.1 ng ml −1, respectively), compared to that obtained in spring (3.0 ng ml −1) and winter (2.5 ng ml −1). During autumn and summer, the ejaculate volume (average of 1.2 and 1.0 ml), sperm output (1159 × 10 6 and 1005 × 10 6 sperm ml −1), sperm mass motility (4.2 and 4.3), sperm progressive motility (83.9 and 82.0%) and percentage live sperm (90.7 and 88.2%, respectively) of the bucks were higher ( P < 0.05) than in the spring (0.6 ml, 880 × 10 6 sperm ml −1, 3.3, 71.5% and 80.2%) and winter (0.7 ml, 863 × 10 6 sperm ml −1, 4.0, 71.5% and 84.9%, respectively). During autumn and summer, the percentage of sperm abnormalities (5.0 and 9.2%) was significantly lower than that in spring (12.9%) and winter (11.2%). The semen pH was slightly alkaline being significantly ( P < 0.05) lower in the autumn (7.1) than in spring (7.3). Data showed season of the year to influence all semen parameters evaluated—indicating that optimal buck performance may be obtained in late summer and autumn. It can thus be said that Markhoz bucks have distinct seasonal spermatogenic activity, with poorer semen characteristics being recorded during winter and spring. This may be a critical obstacle when implementing an intensive breeding system of three kidding seasons in 2 years, with natural mating being implemented.