Photoperiod as a factor for studying fluctuations of seminal traits during breeding and non-breeding seasons

The main purpose of this study was to evaluate the influence of the photoperiod on the seminal traits of crossbreed wool-producing rams throughout one year period. For the effect of photoperiod, two periods were considered: decreasing daylight length (summer and autumn) and increasing daylight length (winter and spring). For this study, 5 Baluchi × Moghani (BL × MG) and 5 Arkharmerino × Moghani (AM × MG) rams were used. Semen collections were performed from first of October, 2010 to the end of September, 2011. After a training period of 2 weeks, semen ejaculates were evaluated for volume, total sperm count/ejaculate (TSE), sperm concentration, semen color, wave motion, percentage of progressive motility, percentage of live and abnormal sperm, pH, methylene blue reduction time (MBRT) and semen index (semen volume × sperm concentration/ml × live sperm% × progressive motility%). Analysis of the yearlong data showed that semen samples with the best quality were collected in September to November (P 0.05), significant seasonal variations of semen traits were observed for all seminal traits except for progressive motility, percentage of live sperm and MBRT. Although there were significant seasonal changes in seminal traits of the crosses; the fresh semen showed adequate quality to be used for breeding purposes throughout the year.