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The role of the rumen and its microbial population in feed efficiency
The biological basis of feed efficiency has been attributed to processes such as protein turnover, tissue metabolism, activity, body composition, heat increment and digestibility. Much of the work that has been and is currently being conducted investigates the role of the ruminal microbial population as part of the explanation of the feed efficiency phenotype. Specific attention has been paid to the methanogenic bacteria and opportunities to simultaneously reduce greenhouse gas emissions from animals through selection for feed efficiency. The research available for review includes whole animal methane emissions measurements, by several techniques, and molecular characterization of the ruminal microbiome with specific attention to the Archaea. Additional work has identified differences in other populations of the rumen, specifically Bacterioidales and Prevotella, may be associated with the efficiency phenotype. The data available do not provide a simple relationship in which selection for feed efficiency has a concurrent reduction in methane emissions or other specific bacterial populations. Rather, the data identifies complex relationships between diet composition, feed intake patterns, level of intake, rumen size and physiology and many other factors associated with the animal and the ruminal fermentation.
Keywords: Feed efficiency, methane