Abstract

The main purpose of this study was to evaluate the influence of photoperiod on the seminal traits of crossbreed wool-producing rams throughout one year period. For the effect of photoperiod (PTP), two periods were considered: Decreasing daylight length (summer and autumn) and the other, increasing daylight length. For this study, 5 Baluchi × Moghani (BL × MG) and 5 Arkharmerino × Moghani (AM × MG) rams were used. Semen collection started from first of October 2010 to end of September 2011. After a training period of 2 weeks, semen ejaculates were evaluated for volume, total sperm/ejaculate (TSE), concentration (SC), color, wave motion (WM), percentage of progressive motility (PM), percentage of live sperm (LS) and abnormal sperm (SAB), pH, methylene blue reduction time (MBRT) and semen index (SI). Analysis of the year long data showed that semen with the best quality was collected in September to November (P < 0.05). Significant seasonal variations of semen traits were observed for all seminal traits except for PM, LS and MBRT. Yet, no statistical differences were found between the crosses (P > 0.05). Although, there were significant seasonal changes in seminal traits of the crosses, the fresh semen showed adequate quality to be used for artificial or natural insemination throughout the year. PTP was found to influence semen production in two genetic groups at 38°02' N, 46°27' E and an altitude of 1567 m above sea level of Iran. However, these effects were not detrimental to the use of rams for breeding purposes throughout the year.

Key words: Genetic group, crossbreed ram, photoperiod, seasonal variation, spermatozoa