Factors affecting semen characteristics and scrotal circumference in Damascus bucks

This study was conducted to evaluate reproductive parameters in Damascus bucks, as influenced by several factors. Scrotal circumference and semen characteristics were assessed in 38 bucks, 17 of which were mature and a 21 yearlings. Body weight (BW), body condition score (BCS) and scrotal circumference were recorded monthly for a period of 1 year, together with semen collection for evaluation. Mature bucks weighed significantly (P < 0.01) more than yearlings and had a significantly (P < 0.01) larger scrotal circumference for the observation period. Sperm concentration, total sperm per ejaculate and viable sperm concentration were higher (P < 0.05) in mature bucks, while the percentage of abnormal sperm was less (P < 0.05) in the mature bucks. Month of the year significantly (P < 0.01) affected the body weight, scrotal circumference, mass motility, progressive motility, sperm concentration, the percentage of abnormal sperm, viable sperm concentration, ejaculate volume and total sperm output. In spring and summer both sperm quantity and quality were higher than that in winter or autumn. Repeatability values ranged from low (0.09) for percentage abnormal sperm and viable sperm concentration to high (0.74) for BW. Results show that season of year influences all parameters evaluated—indicating that optimal male performance may be obtained during the period of increasing day length. © 2003 Elsevier B.V. All rights reserved.