Effect of ejaculation frequency on spermatozoa survival in diluted semen from Pleven Blackhead rams

The effect of ejaculation frequency on spermatozoa survival in diluted Pleven Blackhead ram semen was investigated. Thirty-two ejaculates were examined. From each ram 4 ejaculates were collected at 10-min intervals in the morning and in the afternoon. Semen parameters, namely, color, density, transparency, volume, concentration, motility, and abnormal sperm, for each ejaculate were determined. The sperm motility was assessed from the moment of dilution up to 60 min at 10-min intervals, then again at 90 min and 120 min. The semen characteristics were determined by means of "Motic Image Plus" equipment and the data were processed statistically. Sperm volume and concentration in semen samples decreased gradually with increase in ejaculation frequency. The values were significantly lower for the 4th ejaculate compared to preceding ones (P < 0.05). The highest survival rate (P < 0.05) of sperm was found in the 2nd ejaculate, and this trend was preserved up to the second hour. Up to 50 min after dilution, the sperm motility did not change considerably, after which it was found to be reduced (P < 0.05). The frequency of ejaculation and the period of semen collection had an impact on sperm motility in extended and short-time stored semen from Pleven Blackhead rams. The spermatozoa in a 2nd ejaculate showed higher survival rates and could be recommended for additional processing.