Associations between Rumen Bacteria and Feed Efficiency in Beef Cattle

• Author / Creator

  Hernandez-Sanabria, Emma

• 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.

• Subjects / Keywords

  • PCR-DGGE
  • Rumen bacteria
  • Multivariate statistical analysis
  • RFI
  • Beef cattle

• Graduation date

  Fall 2011

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy in Animal Science

• DOI

  https://doi.org/10.7939/R36615

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.