Location: Dairy Forage ResearchTitle: ARISA Analysis of Ruminal Bacterial Community Dynamics in Lactating Dairy Cows During the Feeding Cycle Author
Submitted to: Anaerobe
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/9/2009
Publication Date: 8/5/2009
Publication URL: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6W9T-4WS9BX0-1&_user=443835&_coverDate=07%2F15%2F2009&_alid=994024418&_rdoc=1&_fmt=high&_orig=search&_cdi=6691&_sort=r&_docanchor=&view=c&_ct=1&_acct=C000020958&_version=1&_urlVersion=0&_userid=443835&md5=430b304a5100379b1590594fd471a304
Citation: Welkie, D.G., Stevenson, D.M., Weimer, P.J. 2010. ARISA Analysis of Ruminal Bacterial Community Dynamics in Lactating Dairy Cows During the Feeding Cycle. Anaerobe. 16:94-100. Available: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6W9T-4WS9BX0-1&_user=443835&_coverDate=07%2F15%2F2009&_alid=994024418&_rdoc=1&_fmt=high&_orig=search&_cdi=6691&_sort=r&_docanchor=&view=c&_ct=1&_acct=C000020958&_version=1&_urlVersion=0&_userid=443835&md5=430b304a5100379b1590594fd471a304 Interpretive Summary: A cow’s rumen (first of four stomach compartments) contains trillions of bacteria that help the cow digest its feed and also provide a valuable source of protein for the cow. But the vast majority of bacterial species in the rumen of the cow have resisted isolation in pure culture (the traditional method of studying bacteria). Thus, we have little knowledge of the bacterial community composition in the rumen. In an effort to improve our ability to study rumen bacteria, we took advantage of differences among species in the size of a particular DNA segment (known as molecular markers) to track populations within the rumen bacterial community over the course of 4 feeding cycles in 2 cows. We found a total of 330 different “species”, nearly one-quarter of which were found in one cow or the other, but not in both, suggesting that individual cows vary substantially in their rumen bacterial populations. The bacterial community associated with feed particles was more stable than the community associated with the rumen liquid phase, reinforcing the importance of forages and particulate feed components (plant cell walls and starches) in promoting a healthy rumen bacterial population. The results of this study will serve as a foundation for efforts to more completely define interactions among important members of the rumen bacterial community in an effort to improve digestion efficiency.
Technical Abstract: The bovine rumen undergoes substantial changes in environmental conditions during the animal’s feeding cycle, but the effects of these changes on microbial populations has not been examined systematically. Two dairy cows fed a mixed forage/concentrate ration at 12 h intervals over 4 feeding cycles displayed substantial changes in ruminal pH and volatile fatty acid (VFA) concentrations. Automated ribosomal intergenic spacer analysis (ARISA) of solid- and liquid-associated bacterial populations in samples collected at 2, 4, 6, 9, and 12 h after feeding revealed a high degree of bacterial diversity (a total of 330 different operational taxonomic units, OTUs). Nearly one-quarter of the OTUs were detected in one cow but not in the other, and a substantial fraction of the OTUs were detected only in the liquid phase or the solid phase (15.4% and 7.3% respectively) of both rumina. Correspondence analysis indicated that by the end of each cycle, the bacterial community returned to a somewhat similar composition. This composition differed between cows and between solid or liquid phases, but overall the solid-associated population displayed less change in composition across feeding cycles. The data support the notion that biofilm communities display greater community stability than associated planktonic populations.