The Effect of Streptomycin upon the Livability and Bacterial Content of Bovine Semen

Abstract

Summary 1.The additions of 100, 250, 500, 750 and 1,000 γ of streptomycin per ml. of diluted semen did not significantly affect the livability of bull spermatozoa during a 20-day storage period. Levels of 1,250, 1,500 and 2,000 γ per ml. of diluted semen brought about a significant decrease in spermatozoan livability during a storage period of 20 days. 2.A significant linear relationship was found between spermatozoan livability and concentration of streptomycin. The mean percentage of motile spermatozoa during storage for 20 days decreased by 0.5 per cent for each addition of 250 γ of streptomycin. 3.Streptomycin inhibited bacterial growth in diluted semen as compared with untreated controls. Levels above 100 γ per ml. were especially effective; the greatest antibacterial activity was obtained in freshly diluted semen and diluted semen stored for 8 days. The initial plate counts for ten ejaculates studied ranged from 2,000 to 350,000 bacteria per ml. of fresh, undiluted semen, with a mean of 73,000 bacteria per ml. 4.There was no significant loss in streptomycin activity in diluted semen stored for 8 and 16 days at 4.5° C.