Location: Dairy Forage ResearchTitle: Host specificity of the ruminal bacterial community in the dairy cow followng near-total exchange of ruminal contents Author
Submitted to: Journal of Dairy Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2010
Publication Date: 12/1/2010
Publication URL: http://hdl.handle.net/10113/48596
Citation: Weimer, P.J., Stevenson, D.M., Mantovani, H., Man, S. 2010. Host specificity of the ruminal bacterial community in the dairy cow followng near-total exchange of ruminal contents. Journal of Dairy Science. 93:5902-5912. Interpretive Summary: The microbial community of the rumen is essential for converting feedstuffs to volatile fatty acids and microbial cell protein used by the dairy cow, yet little is known of the potential specificity of the community for individual cows. We performed two near-total (~95%) exchanges of ruminal contents between two pairs of Holstein cows through their surgically implanted rumen fistulas, and tracked the changes in the composition of the ruminal bacterial community over time. Although the paired cows were fed the same ration, the ruminal bacterial community in each cow generally reassorted itself to more closely resemble that prior to the exchange. The results suggest that changing the ruminal bacterial community is fairly stable, and dairy producers who seek to improve the composition of the ruminal bacterial community (e.g., through the feeding of probiotic microbes) need to consider this resiliency when attempting to modify the community.
Technical Abstract: The purpose of this study was to examine the stability and host specificity of a cow’s ruminal bacterial community following massive challenge with the ruminal microflora from another cow. In each of two experiments, one pair of cows was selected on the basis of differences in ruminal bacterial community composition (BCC), determined by automated ribosomal intergenic spacer analysis (ARISA), a culture-independent “community fingerprinting” technique. Each pair of cows was then subjected to a one-time exchange of >95% of ruminal contents without changing the composition of a corn silage/alfalfa haylage-based TMR. In experiment 1, the two cows differed (P<0.01) in pre-feed ruminal pH (mean = 6.88 vs. 6.14) and pre-feed total VFA concentration (mean = 57 vs 77 mM), averaged over 3 d. Following exchange of ruminal contents, ruminal pH and total VFA concentration in both cows returned to their pre-exchange values within 24 h. Ruminal BCC also returned to its original profile, but this change required 14 d for one cow and 61 d for the other cow. In experiment 2, the two other cows differed (P <0.01) in pre-feed ruminal pH (mean = 6.69 vs. 6.20) and total VFA concentration (mean = 101 vs. 136 mM). Following exchange of ruminal contents, the first cow returned to its pre-exchange pH and VFA values within 24 h; the second cow’s rumen rapidly stabilized to a higher pre-feed pH (mean = 6.47) and lower pre-feed VFA concentration (mean = 120 mM) that was retained over the 62-d test period. Both cows reached somewhat different BCCs than prior to the exchange. However, the BCC of both cows remained distinct and was ultimately more similar to that of the pre-exchange BCC than of the donor animal BCC. The data indicate that the host animal can quickly re-establish its characteristic ruminal pH and VFA concentration despite dramatic perturbation of its ruminal microbial community. The data also suggest that ruminal BCC displays substantial host specificity that can re-establish itself with varying success when challenged with a microbial community optimally adapted to ruminal conditions of a different host animal.