Rumen fermentation and methanogenesis are vital metabolic processes in cattle and are carried out by microbial populations that are affected by dietary factors such as secondary metabolites, nutritional composition and degradability. The aim of this study was to monitor populations of total bacteria, total methanogens and Butirivibrio fibrisolvens in the rumen of Lucerne heifers fed on diets typical of intensive silvopastoral systems (ISS) or of a traditional (control) system. Rumen contents (RC) were collected orally from eight heifers consuming 100% Cynodon plectostachyus (control) and 76% C. plectostachyus + 24% Leucaena leucocephala (ISS) following a crossover design and DNA was extracted and quantified by quantitative PCR. Populations & [Log10 (ng g-1 RC)& ] were 5.6 and 5.8 for total bacteria (p = 0.5343), 3.6 and 3.5 for B. fibrisolvens (p = 0.4742) and 5.0 and 5.3 for total methanogens (p = 0.2661) respectively in control and ISS diets. However, when measured in a separate parallel study, enteric methane emissions (g kg-1 of fermented dry matter) were significantly reduced with the inclusion of L. leucocephala. This fact indicated the importance of investigating the structure, function and interactions of populations beyond quantitative analysis to determine how diet affects rumen microbial populations and their function.
bacteria; diversity; legume; methanogens; Real Time Polymerase Chain Reaction (RT-PCR)
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