Effect of electroejaculation on progesterone and cortisol excretion in bovine semen

Artificial vagina (AV) and electroejaculation (EE) are the 2 methods used to obtain semen from bulls. The purpose in the present study was to evaluate these 2 methods of collection when 2 markers, cortisol and progesterone, were injected IV. During period 1 (control measurement), semen was obtained by EE at 0, 20, 60, 120, and 180 minutes. In period 2, bulls were injected (3 days later) with a mixture of cortisol (113 mg) and progesterone (100 mg), and then samples were obtained by EE. In period 3, cortisol and progesterone were injected (3 weeks later), and samples were obtained by AV. Seminal plasma concentrations of cortisol and progesterone were maximal at 20 minutes in EE and AV collections. Seminal plasma concentrations of progesterone and cortisol were roughly 50% less in EE than in AV collection. However, the total excretion of progesterone and cortisol per collection was similar in both techniques. Excretion of cortisol was 14 to 33 times greater than that of progesterone. It was concluded that concentrations of markers in the EE were significantly less than those in AV collection. For this reason, total excretion and concentration of marker in semen should be accounted for when conducting excretion studies.