HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Thorley, C. M. Articles by Bryant, M. P. Search for Related Content PubMed Articles by Thorley, C. M. Articles by Bryant, M. P.

Modification of the Rumen Bacterial Flora by Feeding Cattle Ground and Pelleted Roughage as Determined with Culture Media with and Without Rumen Fluid

National Institute for Research in Dairying, Reading, England and Department of Dairy Science, University of Illinois, Urbana

ABSTRACT

The numbers and kinds of predominating bacteria and most probable numbers (MPN) of cellulolytic bacteria were determined in an experiment designed as a 2 x 2 Latin square, with two nonlactating cows fed diets ad libitum consisting of artificially dried grass and the same grass ground and pelleted. Two nonselective anaerobic roll tube media—a rumen fluid medium (Medium 98-5) and one in which rumen fluid was replaced by volatile fatty acids, heme, and small amounts of yeast extract and trypticase (Medium 10) were used to obtain colony counts and to isolate strains for presumptive identification. The mean colony count for Animal D, 15.2 x 10⁹ per gram, was significantly higher than that for Animal C, 11.1 x 10⁹ per gram. Counts were highly significantly higher when animals were fed ground grass (15.7 x 10° per gram) as compared to long grass (10.5 x 10⁹ per gram), and there was a highly significant difference between mean counts on Medium 10 (15 x 10⁹ per gram) and Medium 98-5 (10.7 x 10⁹ per gram). Much of the difference in counts for both culture media and diets was due to the much higher mean counts on Medium 10 (20.7 x 10⁹ per gram) as compared to Medium 98-5 (10.9 x 19⁹ per gram) when ground grass was fed. The MPN of cellulolytic bacteria were similar for the two animals when long grass was fed and for Animal C when either diet was fed. These counts were depressed when Animal D was fed ground grass. The presumptive identification of 74 to 109 strains of predominating bacteria, isolated from each medium inoculated from each animal on each diet, showed a remarkable similarity in distribution of species in the two animals when long grass was fed. The distribution of species changed when ground grass was fed and under this condition distribution in the two animals was different. The results indicate that changes in the rumen fermentation which occur when high levels of ground forage are fed are partially owing to changes in the distribution of microbial species present and show that Medium 10 is an excellent medium for enumeration and isolation of diverse species of rumen bacteria.

¹ Present address: Department of Pharmacy, City of Liverpool College of Technology, Liver-pool 3, England.

² N.I.R.D., Shinfield, Reading, England.