Biophysical and 1H magnetic resonance spectroscopy characteristics of fractionated stallion ejaculates

The composition of seminal plasma must be determined to assess the possible roles of sex gland secretions in survival of stallion spermatozoa. In the present study, an automated semen collection device and 1H magnetic resonance spectroscopy were used to analyse and compare the composition of seminal plasma from fractionated and nonfractionated stallion ejaculates. The contribution of each semen component to the ejaculate (sequence of production of component and concentration) was evaluated and its relationship to biophysical parameters was determined. 1H magnetic resonance spectroscopy was used to quantify molecules defined as markers of sex gland secretions: carnitine, glycerophosphorylcholine and choline for the epididymides; N-acetyl function of glycoproteins and spermine for the ampullae; acetic acid for the bulbourethral glands; and citric acid for seminal vesicles. The results from 32 ejaculates (four ejaculates from each of four stallions by two collection methods) demonstrated the reliability of the 1H magnetic resonance spectroscopy quantitation, the sequence of sex gland secretion contributions to the ejaculate (bulbourethral glands, epididymides, ampullae and seminal vesicles) and the concomitant appearance of the sperm-rich fraction with secretions from the epididymides and ampullae.