title: Effects on enteric methane production and bacterial and archaeal communities by the addition of cashew nut shell extract or glycerol-an in vitro evaluation.
abstract: The objective of the study was to evaluate the effect of cashew nut shell extract (CNSE) and glycerol (purity >99%) on enteric methane (CH4) production and microbial communities in an automated gas in vitro system. Microbial communities from the in vitro system were compared with samples from the donor cows, in vivo. Inoculated rumen fluid was mixed with a diet with a 60:40 forage:concentrate ratio and, in total, 5 different treatments were set up: 5mg of CNSE (CNSE-L), 10mg of CNSE (CNSE-H), 15mmol of glycerol/L (glycerol-L), and 30mmol of glycerol/L (glycerol-H), and a control without feed additive. Gas samples were taken at 2, 4, 8, 24, 32, and 48h of incubation, and the CH4 concentration was measured. Samples of rumen fluid were taken for volatile fatty acid analysis and for microbial sequence analyses after 8, 24, and 48h of incubation. In vivo rumen samples from the cows were taken 2h after the morning feeding at 3 consecutive days to compare the in vitro system with in vivo conditions. The gas data and data from microbial sequence analysis (454 sequencing) were analyzed using a mixed model and principal components analysis. These analyses illustrated that CH4 production was reduced with the CNSE treatment, by 8 and 18%, respectively, for the L and H concentration. Glycerol instead increased CH4 production by 8 and 12%, respectively, for the L and H concentration. The inhibition with CNSE could be due to the observed shift in bacterial population, possibly resulting in decreased production of hydrogen or formate, the methanogenic substrates. Alternatively the response could be explained by a shift in the methanogenic community. In the glycerol treatments, no main differences in bacterial or archaeal population were detected compared with the in vivo control. Thus, the increase in CH4 production may be explained by the increase in substrate in the in vitro system. The reduced CH4 production in vitro with CNSE suggests that CNSE can be a promising inhibitor of CH4 formation in the rumen of dairy cows.
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, SE-75323, Uppsala, Sweden. Electronic address: rebecca.danielsson@slu.se.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Danielsson
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, SE-75323, Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Werner-Omazic
authors.affiliation: Department of Agricultural Research for Northern Sweden, Swedish University of Agricultural Sciences, SE-901 83, Umeå, Sweden.
authors.forename: Mohammad
authors.initials: M
authors.lastname: Ramin
authors.affiliation: Department of Microbiology, Swedish University of Agricultural Sciences, SE-75007, Uppsala, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Schnürer
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, SE-75323, Uppsala, Sweden.
authors.forename: Mikko
authors.initials: M
authors.lastname: Griinari
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, SE-75323, Uppsala, Sweden.
authors.forename: Johan
authors.initials: J
authors.lastname: Dicksved
authors.affiliation: Department of Animal Nutrition and Management, Swedish University of Agricultural Sciences, SE-75323, Uppsala, Sweden.
authors.forename: Jan
authors.initials: J
authors.lastname: Bertilsson
mesh_terms: D031021:Anacardium / Q000737:chemistry*; D000818:Animals; D001105:Archaea / Q000145:classification / Q000378:metabolism; D001419:Bacteria / Q000145:classification / Q000378:metabolism; D018533:Biomass; D002417:Cattle; D004032:Diet / Q000662:veterinary; D004305:Dose-Response Relationship, Drug; D005232:Fatty Acids, Volatile / Q000096:biosynthesis; D005260:Female; D005285:Fermentation; D005990:Glycerol / Q000008:administration & dosage*; D008697:Methane / Q000096:biosynthesis*; D009754:Nuts / Q000737:chemistry; D010936:Plant Extracts / Q000008:administration & dosage*; D025341:Principal Component Analysis; D012417:Rumen / Q000382:microbiology; D017422:Sequence Analysis, DNA; D012820:Silage / Q000032:analysis*
chemical_list: D005232:Fatty Acids, Volatile; D010936:Plant Extracts; D008697:Methane; D005990:Glycerol
keywords: cashew nut shell extract; glycerol; in vitro; methane production