Abstract
It is very important to control bacterial contamination of bull semen not only for maintaning good fertility in artificial insemination by the semen but for preventing genital infection in the cow served by it. For this purpose sulfanilamide, penicillin and dihydrostreptomycin are customarily added to semen diluents. Since 1957 I have been studied on the prevention of bacterial contamination of bull semen.
The purpose of the work presented here was to investigate the actual condition of bacterial contamination of original bull semen. A total of 221 semen samples collected from breeding bulls were used as meterial. The results obtained were as follows;
1) Degree of the bacterial contamination of original bull semen was considerably high, the number of bacteria recovered being from 2×103/ml to 1.7×107/ml. In 48 (21.7 %) of the 221 semen samples examined, the number of bacteria was over 106/ml (Table 1).
2) The number of bacteria in semen from the bull in which preputial douche had been performed before semen collection decreased markedly as compared to that without preputial douch (Table 1 and Fig. 1). The effect of the preputial duoche for preventing bacterial contamination of semen was confirmed experimentally (Table 2).
3) From 219 original semen samples 750 strains of bacteria were recovered as shown in Table 3. Almost all of them were determined as non-pathogenic or saprophytic bacteria. It was supposed that the bacteria were derived primarily from the preputial cavity of the bull.
