Aust. J. Bioi. Sci., 1976, 29, 545-55 Ejaculated spermatozoa from rams given intramuscular injections of

The free amino acid content of rete testis fluid, epididymal fluid, vesicular fluid and ejaculated seminal plasma was studied in the ram, bull and rat, and a comparison made with the blood plasma of the same species. The amino acid content of human seminal plasma and the various fractions of the boar ejaculate was also determined.Glutamic acid was found to be the predominant amino acid in the secretions of the reproductive tract of the ram and bull. It is present in high concentrations in the rete testis fluid of both species, and is further concentrated along the tract. In the rat glycine and alanine are the predominant amino acids in the rete testis fluid, while glutamic acid is the principal amino acid in epididymal fluid, as in the other species studied. Glycine is also the principal amino acid in human seminal plasma. The concentration of amino acids is greatest in the sperm-rich fraction of the boar ejaculate.The breakdown of protein to amino acid was studied in ram and bull semen. This is at least partly due to enzymically induced changes.