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

Abstract

The purpose of this study was to examine the relationships between blood plasma free and total testosterone (FT and TT) and some seminal markers. Semen ejaculates and blood samples were collected early in the morning at weekly intervals for 2 years from 10 Manchego rams. The semen ejaculated were tested 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. The relationship between the two types of testosterone and sperm concentration, fructose and citric acid was investigated. The coefficients of correlation 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. Plasma testosterone peaked in the second week of September and this week was defined as week 0. Maximum coefficients of correlation between free testosterone 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 observed to occur following the free testosterone peak after 7 (fructose and sperm concentration) and 5 (citric acid) weeks, between mid-October and early November. Maximum coefficients of correlation between free and total testosterone 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, like those of free testosterone, were observed to occur following the total testosterone peak after 9 (fructose and sperm concentration) and 11 (citric acid) weeks between mid and late November. Results demonstrate that both free testosterone and total testosterone influence fructose and citric acid secretion even within the breeding season, and that the chemical composition of seminal plasma depends on the type of circulating testosterone that is considered. There were no significant effects of either free testosterone or total testosterone on sperm concentration.