The effect of frequent ejaculation in the ram on some semen characteristics

Abstract

(1) Series of 13 ejaculates per day for 10 successive days were collected from each of five Merino rams. Every third ejaculate was examined for volume, density, and fructose and citric acid concentrations — 250 samples in all. (2) The mean fructose and citric acid concentrations were 596 and 91 mg% respectively. While the mean fructose concentrations differed significantly (P < 0.001) during the successive 10 days of collection, the citric acid concentrations did not. Both seminal constituents declined with ejaculates within days (P < 0.01 ; P< 0.001). There were significant declines in mean volume and density and an increase in mean reaction time with successive days and with collections within days (P < 0.001). Rams differed significantly in all characteristics examined (P < 0.001). (3) Multiple factor analysis revealed that three factors were mainly responsible for variances in the characteristics studied during the 10 days and within days of collection. The variances in characteristics contributed to by sequence of ejaculates in individual rams over the 10 days were: 68–96% for volume, 90–100% for density, 28–98% for reaction time, and practically nil for fructose and citric acid concentrations. There were marked ram differences in contribution of the sequence of ejaculates to the within-day variance in volume (0–90%), density (0–98%), citric acid concentration (0–98%, and reaction time (0–97%). The ejaculates collected had practically no contribution to the within-day variance in fructose concentration. (4) The rams with relatively low sexual response (long mean reaction time) tended to ejaculate semen of relatively high volume and with high concentrations of fructose and citric acid.