Effect of reproductive season and semen collection on the concentration of some reproductive hormones of Awassi rams

Abstract

The study was conducted to estimate the concentration of Follicle Stimulating Hormone (FSH), Interstitial Cell Stimulating Hormone (ICSH) and Testosterone (T) in Awassi ram serum, the effect of reproductive seasons and semen collection on the concentration of these hormones. Six Awassi rams, aged 3-4 years and weighted 55-60 kg, were used in this study. Artificial vagina was used for semen collection every two weeks along the study period (July 2010 to February 2011). Semen samples were evaluated immediately after collection to determine volume, mass, individual motility and sperm concentration. Blood samples were collected before and after 30 min. of semen collection. The concentration of T was evaluated by ELISA, and concentration of FSH and ICSH were determined using the Immunofluorescence assay. Results showed that the average concentration of T, FSH and ICSH were 2.33 ± 0.22, 1.60 ± 0.20 and 0.53 ± 0.17 ng/ml, respectively. There was no significant variation between rams in all three determined hormones. The concentration of T and ICSH was highly significant (P<0.05) in autumn than in summer and winter. There was a significant (P<0.05) variation observed in concentration of T between summer and winter, while no variation in FSH concentration between the year seasons. The concentration of T during the reproductive season was highly significant (P<0.001) than its concentration out of season. There was a significant (P<0.001) increase in T concentration after semen collection. The concentration of T and ICSH has a positive relationship with ejaculate volume, and negative relationship with other semen parameters. The relationship was negative between FSH and sperm concentration and positive with other sperm parameters. Only a significant (P<0.05) negative correlation (r = -0.773) was observed between T and sperm concentration. The relationship was negative between T and ICSH and positive between T and FSH, and a significant (P<0.001) negative correlation (r = -0.663) was observed between ICSH and FSH. It be concluded that the higher sexual activity of Awassi rams was in autumn especially in October, and only the T was affected by reproductive season and increased after semen collection.