Bacteriological Studies of Bovine Semen. I. Numbers of Bacteria and the Relation to Fertility

Summary 1. Wide variations were found in the bacterial plate counts of semen from various bulls and in the counts of semen collected at different times from the same animal. The plate count on 202 ejaculates from 36 bulls ranged from less than 100 to more than 3 million organisms per ml., with an average of 200,000 per ml. 2. No significant differences were observed in the plate counts of first and second ejaculates collected in succession from the same bull. Plate counts for 91 paired ejaculates showed 220,000 bacteria per ml. for first ejaculates and 130,000 per ml. for second ejaculates. 3. There was no apparent relationship between the average plate counts of semen and the general fertility level of bulls. 4. There was no important relationship between the age of bulls and the average plate count of semen.