Seasonal variation in semen characteristics, scrotal circumference and libido of Persian Karakul rams

The aim of the present studywas to evaluate seasonal changes in semen characteristics of Persian Karakul rams. Six Karakul rams (3–4 years old) were trained to serve the artificial vagina. Semen collection was performed every 2 weeks, commencing in January (at onset of winter) to December (end of autumn) 1999. Semen ejaculates were evaluated for volume, total sperm output, mass motility and the percentage live sperm. Moreover, changes in the scrotal circumference, body weights, libido and plasma testosterone concentrations of the rams were also recorded at 2-week intervals. The semen was characterized by a mean (±S.D.) ejaculate volume of 1.2 ± 0.3ml, a mean (±S.D.) mass motility of 3.8 ± 0.8, and a total number of 4442±1247 (×106) sperm per ejaculate for the observation period. The overall mean (±S.D.) scrotal circumference recorded was 32.0 ± 1.2 cm. Seasonal variations (P < 0.05) were recorded for semen volume, mass motility, scrotal circumferences and plasma testosterone concentrations, but not for the total sperm output. In conclusion, albeit there were seasonal changes in semen characteristics of Karakul rams, the semen has the capability and quality to be used for artificial insemination all year round. Semen of superior quality and quantity was especially collected in late summer and throughout autumn. © 2003 Elsevier B.V. All rights reserved