Seasonal variations in semen quality of local and crossbred rams raised in the United Arab Emirates.

Abstract

A total number of 900 semen ejaculates were collected by means of artificial vagina from 10 rams (five local and five crossbreed 'local x chios'). Each ram was scheduled for semen collection three times per week at equal intervals for approximately two months in each season. At each collection, two separate successive ejaculates were obtained. Semen ejaculates were tested for volume, pH, mass motility, methylene blue reduction time (MBRT) and sperm-cell concentration per milliliter. Sex drive of rams was estimated by measuring the reaction time (RT). The time from the first to the second ejaculate was also recorded (TBE). Data of the two breeds show that the overall means for seminal attributes were 0.75 ml, 6.82, 4.2, 216.1 s and 5102.26 x 10(6) sperm/ml, respectively. In both breeds the overall means for RT and TBE were 43.7 and 152.3 s, respectively. Excluding ejaculate volume and MBRT, breed of ram was without significant effect on the investigated seminal characters, and sex drive parameters. Semen of the second ejaculate was significantly (P < 0.01) less in volume, greater in motility, closer to neutrality, less in sperm-cell concentration. MBRT of the two ejaculates differed nonsignificantly. However, characteristics of the second ejaculate fell within the normal range of high quality semen. Although the tested rams are continuous breeding animals, yet seasonal variations in semen characteristics were observed. The best-quality semen occurred in winter (volume, 0.77 ml; pH, 6.95; motility, 4.53; MBRT, 3.24 min. and sperm concentration, 4932.72 x 10(6)/ml). According to the known indices of semen quality of the ram, semen of the other seasons is judged to be of good quality. The mean RT for both breeds was less than one minute. Breed effect on RT and BET was insignificant. Season of the year exerted a significant (P < 0.01) effect on RT. The shortest time was recorded in summer, whereas the longest one was that of autumn. This indicates that the high ambient temperature of summer, prevailing in this locality, did not decrease the sexual activity of the tested rams.