Correlation between blood plasma levels of free and total testosterone andconcentrations of some seminal markers in adult Manchego rams

The purpose of this study was to examine the relationships between blood pl asma free and total testosterone (FT and TT) and some seminal markers. Seme n ejaculates and blood samples were collected early in the morning at weekl y intervals for 2 years from 10 Manchego rams. The semen ejaculated were te sted for sperm concentration (SC), seminal plasma samples were analyzed for fructose (F) and citric acid (CA) concentrations and blood plasma samples were assayed for free testosterone and total testosterone concentrations. T he relationship between the two types of testosterone and sperm concentrati on, fructose and citric acid was investigated. The coefficients of correlat ion between maximum values of free testosterone and total testosterone and the values of fructose, citric acid and sperm concentration, corresponding to 0, 1 and 2, until 13 weeks after testosterone peaks were observed. Plasm a testosterone peaked in the second week of September and this week was def ined as week 0. Maximum coefficients of correlation between free testostero ne and fructose, sperm concentration and citric acid were 0.98 (P < 0.001), 0.44 (P < 0.01) and 0.89 (P < 0.001), respectively. These values were obse rved to occur following the free testosterone peak after 7 (fructose and sp erm concentration) and 5 (citric acid) weeks, between mid-October and early November. Maximum coefficients of correlation between free and total testo sterone and fructose, sperm concentration and citric acid were 0.98 (P < 0. 001), 0.24 (P < 0.05) and 0.82 (P < 0.001), respectively. These values, lik e those of free testosterone, were observed to occur following the total te stosterone peak after 9 (fructose and sperm concentration) and 11 (citric a cid) weeks between mid and late November. Results demonstrate that both fre e testosterone and total testosterone influence fructose and citric acid se cretion even within the breeding season, and that the chemical composition of seminal plasma depends on the type of circulating testosterone that is c onsidered. There were no significant effects of either free testosterone or total testosterone on sperm concentration. (C) 1999 Elsevier Science B.V. All rights reserved.