SUCCESSION OF STREPTOCOCCUS-BOVIS STRAINS WITH DIFFERING BACTERIOPHAGE SENSITIVITIES IN RUMENS OF 2 FISTULATED SHEEP

The bacteriophage sensitivity of the S. bovis population resident in the rumens of 2 fistulated sheep was monitored for 112 days. During this time 3 changes in the bacteriophage sensitivity of S. bovis occurred in the absence of detectable bacteriophages. Identical changes in bacteriophage sensitivity occurred simultaneously in both animals, and except for the relatively short periods of changeover in phage sensitivity, the S. bovis population in the rumens of the 2 sheep was homogeneous with respect to phage sensitivity.