Microorganisms in the rumen of cattle fed a constant ration
1957
Hungate, R. E.
Direct microscopic and culture counts were made on samples of rumen contents obtained by stomach tube from each of 25 cows at monthly intervals during 3 months. The ration was timothy hay plus various amounts of cottonseed meal, rolled barley, and salt. No correlation between different rations and differences in the microbiota could be detected. Streptococcus bovis was identified by its rapid growth in the feed medium and showed counts ranging between 2 × 10⁵ and 1.4 × 10⁸. Most animals showed a S. bovis count between 1 and 20 million with an average of about 10 million per milliliter. The characteristics of some rumen strains are described. The cellulose-digesting bacteria were referable to four chief groups and the numbers of each were recorded. The cellulolytic cocci varied in almost every character studied. Two types were distinguished as representing the greatest divergence. Ruminococcus albus n. sp. differs from R. flavefaciens in being Gram-negative, forming little or no yellow pigment, and producing no succinic acid. A cellulose-digesting sporeformer, Clostridium lochheadii n. sp., was found in many of the samples. It was extremely active in digesting cellulose, exceeding in this respect the species of anaerobic cellulose digesters previously isolated. Spores were formed in abundance but rapidly disintegrated and many strains were lost before subculture. Clostridium longisporum n. sp. was encountered during the investigation and is described.
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