Plasma Hormonal Levels of Rams are Affected by Sexual Activity and Confinement in a Semen Collection Centre

Two experiments were carried out to determine the effect of sexual activity and confinement in a semen collection centers (SCC) on plasma hormonal concentrations of rams. In experiment 1, rams were introduced into the flocks (active, n=29) or not, remained stabled with no access to the ewes (inactive, n=22). In experiment 2, animals were either at commercial flocks (n=89) or at a SCC (n=62). Rams were divided into active (n=65), and inactive (n=86). Plasma progesterone concentrations were not affected by sexual activity, management or breed. Plasma testosterone (P<0.001), progesterone (P<0.05), estradiol (P<0.05) and cortisol (P=0.01) concentrations were significantly affected by sexual activity, and testosterone (P<0.05) and progesterone (P<0.05) also by breed. Plasma estradiol concentrations were significantly modified by activity (P<0.001), management (P<0.001) and breed (P<0.05). Plasma cortisol levels were only affected by place (P=0.001). Plasma hormonal levels under study were affected by sexual activity when rams are in the flock. The higher levels of plasma cortisol presented by rams allocated in the SCC could indicate some degree of stress, although the absence of correlation between semen quality and hormonal levels suggests that restrain does not affect semen characteristics.