title: Methane Production in Dairy Cows Correlates with Rumen Methanogenic and Bacterial Community Structure.
abstract: Methane (CH4) is produced as an end product from feed fermentation in the rumen. Yield of CH4varies between individuals despite identical feeding conditions. To get a better understanding of factors behind the individual variation, 73 dairy cows given the same feed but differing in CH4emissions were investigated with focus on fiber digestion, fermentation end products and bacterial and archaeal composition. In total 21 cows (12 Holstein, 9 Swedish Red) identified as persistent low, medium or high CH4emitters over a 3 month period were furthermore chosen for analysis of microbial community structure in rumen fluid. This was assessed by sequencing the V4 region of 16S rRNA gene and by quantitative qPCR of targetedMethanobrevibactergroups. The results showed a positive correlation between low CH4emitters and higher abundance ofMethanobrevibacter ruminantiumclade. Principal coordinate analysis (PCoA) on operational taxonomic unit (OTU) level of bacteria showed two distinct clusters (P< 0.01) that were related to CH4production. One cluster was associated with low CH4production (referred to as cluster L) whereas the other cluster was associated with high CH4production (cluster H) and the medium emitters occurred in both clusters. The differences between clusters were primarily linked to differential abundances of certain OTUs belonging toPrevotella. Moreover, several OTUs belonging to the family Succinivibrionaceae were dominant in samples belonging to cluster L. Fermentation pattern of volatile fatty acids showed that proportion of propionate was higher in cluster L, while proportion of butyrate was higher in cluster H. No difference was found in milk production or organic matter digestibility between cows. Cows in cluster L had lower CH4/kg energy corrected milk (ECM) compared to cows in cluster H, 8.3 compared to 9.7 g CH4/kg ECM, showing that low CH4cows utilized the feed more efficient for milk production which might indicate a more efficient microbial population or host genetic differences that is reflected in bacterial and archaeal (or methanogens) populations.
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences Uppsala, Sweden.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Danielsson
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences Uppsala, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Dicksved
authors.affiliation: Department of Microbiology, Swedish University of Agricultural Sciences Uppsala, Sweden.
authors.forename: Li
authors.initials: L
authors.lastname: Sun
authors.affiliation: Departamento de Producción Animal, Facultad de Ciencias Veterinarias, UNCPBA Tandil, Argentina.
authors.forename: Horacio
authors.initials: H
authors.lastname: Gonda
authors.affiliation: Department of Microbiology, Swedish University of Agricultural Sciences Uppsala, Sweden.
authors.forename: Bettina
authors.initials: B
authors.lastname: Müller
authors.affiliation: Department of Microbiology, Swedish University of Agricultural Sciences Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Schnürer
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences Uppsala, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Bertilsson
keywords: CH4; Methanobrevibacter; digestibility; microbial community; rumen