The effect of mixing ejaculates from different bulls on motility characteristics and acid production of the spermatozoa in a constant environment

Abstract

Motility characteristics of bull spermatozoa in mixed ejaculates of different bulls were compared with those of the unmixed samples after 40-to 50-fold dilution with clarified standard egg-yolk—citrate buffer (pH 6·80 ± 0·05 at 37° C., 6·75 ± 0·05 at 22–23° C).Using the photo-electric equipment described by Rikmenspoel (1957b) and by Rikmenspoel & Van Herpen (1957) the mean velocity , the number of spermatozoa passing by a constant spot per time unit n, the total number of spermatozoa moving normally N, the velocity decrease with time ( — d/dt), the half-life period of the number of passages per time unit t½(n) and the half-life period of the total number of spermatozoa moving normally t½(N) were determined. For none of these characteristics was any statistical difference found between the actual results and the expected values based on calculation from the data obtained with the unmixed ejaculates.Acid production was investigated by accurate determination of pH change on incubation of samples diluted ten times with standard egg-yolk—citrate buffer containing 736 mg. added fructose per 100 ml. Again there was no statistical difference between the values found with the mixed semen samples and the expected values.It is concluded that differences observed by other authors must be due to the effect of environmental factors, i.e. to the semmal plasma, for which there is analogous evidence in human sperm physiology.