The Effect of Bacteria on the Fertility of Bovine Semen

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Abstract
The problems associated with the presence of bacteria in semen have received considerable attention in recent years. Various workers (3, 6, 9, 14) have re- ported on the number of bacteria found in bull semen collected with an arti- ficial vagina. The number in undiluted semen has been found to range from less than 100 to 22,000,000 bacteria per milliliter and in diluted samples from 200 to 3,400,000 organisms per milliliter. Gunsalus et al. (14) have shown that cleaning of bulls materially affects the bacterial count, however. Foote and Salisbury (11) found more bacteria in the first than in subsequent ejaculates and fewer organisms in the semen from bulls of known high fertility than in the semen from other bulls studied. In contradiction to these findings, Almquist et al. (6) found no significant differences between the count~ on 91 first and 91 second ejaculates and no significant relationship between fertility and the number of bacteria present in the undiluted semen. The types of organisms which have been isolated from semen by various workers (9, 10, 14) are Pseudomonas, Streptococcus, Micrococcus, Bacillus, dip- theroids, coliform organisms, actinomycetes and yeast. Dondero (9) has pointed out that the sources of bacteria in diluted bull semen are many, i.e., the genital tract of the bull, surface areas, non-sterile diluter, etc. The possibility of certain bacteria having a detrimental, direct effect on sperm has received some attention. Edmondson et al. (10) found that hemolytic bacteria decreased the length of time semen could be stored, whereas certain non-hemolytic organisms increased the storage time from 1 to 4 days over the controls. Gunsalus et al. (14) noted that E. coli improved the motility of sper- matazoa in semen samples into which it was inoculated. Clinical observations by Williams (22) and Gunsalus et al. (14) have indi- cated that bulls harboring bacteria such as Streptococcus viridans or Pseudo- monas aeruginosa often may have a low breeding efficiency. These and other organisms have been isolated by several workers (13, 14, 23) from bulls that were practically or completely sterile. Similarly, the work of several investi- gators (7, 21, 22) has shown that certain organisms, many of which frequently are found in semen, often are associated with conditions in cows such as vagini- tis, cervicitis, metritis, salpingitis, ovarian bursitis or tubo-ovarian abscesses.