Characteristics of Mycoplasma strains isolated from stallion semen.

Eleven mycoplasma strains were isolated from the semen of 24 stallions. Eight of these strains were identified as Mycoplasma equigenitalium. Three strains which hydrolized arginine could not be identified. The growth inhibition test with immune sera against M. arginini and M. equirhinis was negative. Antibiotic sensitivity test showed that all strains were sensitive to four antibiotic of tetracycline group (oxytetracyclin, minocycline, transcycline and vibramycin). Lincomycin and gentamycin appeared to be the most active against all the strains. Comparative analysis of routine semen examination did not reveal any difference between ejaculates infected with mycoplasma and free of these organisms. However, the levels of certain biochemical components of the semen plasma (glycerylphosphorylcholine, ergothioneine, fructose and of the semen plasma (glycerylphosphorylcholine, ergothioneine, fructose and total protein) from mycoplasma-positive ejaculates were significantly lower than in the semen plasma from mycoplasma free ejaculates.