Seasonal variation in semen quantity and quality traits of Iranian crossbred rams

Abstract

Evaluation of the seasonal changes in seminal traits of 10 crossbred rams (2-6 year old) was the main purpose of the present study. The crossbred rams consisted of 5 Ghezel×Baluchi (GH×BL) and 5 ArkharMerino×Ghezel (AM×GH). Semen was evaluated for volume, total spermatozoa per ejaculate (TSE), spermatozoa concentration (SC), semen colour, wave motion, sperm progressive motility, percentage of live and abnormal spermatozoa, semen pH, methylene blue reduction time (MBRT) and semen index. Semen index of GH×BL and AM×GH rams in autumn was greater than in spring. Best semen quality was observed in late summer and first autumn month. In AM×GH rams the highest values of TSE, SC and semen colour were recorded during winter. However, there were no significant differences between autumn and summer months except for the semen colour (P<0.05). In both the genetic groups the highest and the lowest values of wave motion, progressive motility and live spermatozoa were observed during autumn and spring, respectively. The data showed that the optimal performance of the crossbred rams has been obtained in late summer and the beginning autumn. Seasonal variations of semen characteristics were observed for all of the seminal traits except for the wave motion and MBRT. In conclusion, there were seasonal variations between the crosses in seminal traits and the semen has the capability and quality to be used for AI in breeding programmes throughout the year.