The Effect of Penicillin upon the Livability, Glycolysis, and Bacterial Content of Bovine Semen1,2

Abstract

Summary 1. The addition of 250, 500, and 750 Oxford units of penicillin per ml. of diluted semen did not significantly reduce the ability of spermatozoa to maintain motility during a storage period of 20 days. Levels of penicillin ranging from 1,000 to 2,000 units per ml. of diluted semen brought about a significant decrease in spermatozoan livability during a 20-day storage period. 2. In routine artificial breeding, semen is seldom used after holding more than 6 days. When compared with untreated control samples, no significant decrease in maintenance of spermatozoan motility during a 6-day storage period occurred as the result of addition of 250, 500, 750, or 1,000 units of penicillin per ml. of diluted semen, but higher levels of penicillin were deleterious. 3. Within the limits of laboratory experiment, the relation between spermatozoan livability and level of penicillin is well represented by a straight line, the mean percentage of motile spermatozoa during storage for 20 days decreasing by 0.9 per cent for each additional 250 units of penicillin. 4. Penicillin depressed the utilization of glucose at all levels studied (250 to 2,000 units per ml. of diluted semen), while the amounts of lactic acid which accumulated were not significantly affected. Addition of penicillin increased the percentage of glucose utilized which was recovered as lactic acid. 5. Penicillin retarded bacterial growth at all levels in both freshly diluted semen and diluted semen stored for 8 days, whereas considerable growth was found in the semen without penicillin. The initial plate counts for the five ejaculates studied ranged from 200 to 960,000 bacteria per ml. of undiluted semen, with a mean of 364,000 bacteria per ml. 6. There was no appreciable loss in penicillin activity in diluted semen stored for 8 days and only a slight decrease in concentration after storage for 16 days at 4.5° C.