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Associations between Rumen Bacteria and Feed Efficiency in Beef Cattle Open Access


Other title
Beef cattle
Rumen bacteria
Multivariate statistical analysis
Type of item
Degree grantor
University of Alberta
Author or creator
Hernandez-Sanabria, Emma
Supervisor and department
Guan, Leluo (AFNS)
Examining committee member and department
Zijlstra, Ruurd (AFNS)
Wang, Zhiquan (AFNS)
Oba, Masahito (AFNS)
Keddie, Andrew (Biological Sciences)
Firkins, Jeffrey Lynn (Ohio State University)
Department of Agricultural, Food and Nutritional Science

Date accepted
Graduation date
Doctor of Philosophy in Animal Science
Degree level
Feed efficiency affects profitability and sustainability in beef production systems. Since ruminal microbes play essential roles in feed digestion and conversion, the overall objective of this project was to investigate the association between ruminal bacteria and feed efficiency of beef cattle. PCR-Denaturing Gradient Gel Electrophoresis (PCR-DGGE) was applied to investigate ruminal microbial communities. A statistical model was developed to link the PCR-DGGE band patterns to host phenotypic measurements such as feed efficiency and rumen fermentation variables. Therefore, we determined how the numbers and species of ruminal bacteria present varied dependently as well as independently from diet and their associations with feed efficiency. Likewise, the impact of these interactions on the metabolic capacity and feed efficiency of the host was assessed. Study 1 demonstrated that particular bacteria in the rumen contributed to differences in feed efficiency when host was fed low energy diet. Study 2 evaluated whether structure of bacterial populations remained stable in spite of the dietary changes; we also determined how specific bacterial groups could impact the feed efficiency under low and high energy density diets. Populations of three bacterial species (Succinivibrio sp., Eubacterium sp., and Robinsoniella sp.) were identified to be correlated with feed efficiency measurements; their predicted metabolic mechanisms influencing feed efficiency were proposed (propionate synthesis, formate production and cross-feeding interaction with methanogens). Furthermore, host factors were elucidated in Study 3. Frequency analysis of bacterial PCR–DGGE bands showed that Prevotella sp. was abundant in Angus rumen liquid and contents while Clostridium sp. was present in contents and tissue from Charolais steers. Rumen tissue from Hybrid animals presented high frequency of Prevotella sp. but no species were particularly abundant in liquid, suggesting a strong association between host and the colonization of rumen bacteria. This is the first study linking rumen microbial diversity and microbial metabolites to host feed efficiency traits and their implications on individual variations in Residual Feed Intake of beef cattle.
License granted by Emma Hernandez-Sanabria ( on 2011-09-27T21:00:45Z (GMT): Permission is hereby granted to the University of Alberta Libraries to reproduce single copies of this thesis and to lend or sell such copies for private, scholarly or scientific research purposes only. Where the thesis is converted to, or otherwise made available in digital form, the University of Alberta will advise potential users of the thesis of the above terms. The author reserves all other publication and other rights in association with the copyright in the thesis, and except as herein provided, neither the thesis nor any substantial portion thereof may be printed or otherwise reproduced in any material form whatsoever without the author's prior written permission.
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