title: Influence of ruminal methane on digesta retention and digestive physiology in non-lactating dairy cattle.
abstract: Enteric methane (CH4) production is a side-effect of herbivore digestion, but it is unknown whether CH4 itself influences digestive physiology. We investigated the effect of adding CH4 to, or reducing it in, the reticulorumen (RR) in a 4×4 Latin square experiment with rumen-fistulated, non-lactating cows, with four treatments: (i) control, (ii) insufflation of CH4 (iCH4), (iii) N via rumen fistula, (iv) reduction of CH4 via administration of bromochloromethane (BCM). DM intake (DMI), apparent total tract digestibility, digesta mean retention times (MRT), rumen motility and chewing activity, spot breath CH4 emission (CH4exhal, litre/kg DMI) as well as CH4 dissolved in rumen fluid (CH4RRf, µg/ml) were measured. Data were analysed using mixed models, including treatment (or, alternatively, CH4exhal or CH4RRf) and DMI relative to body mass0·85 (rDMI) as covariates. rDMI was the lowest on the BCM treatment. CH4exhal was highest for iCH4 and lowest for BCM treatments, whereas only BCM affected (reduced) CH4RRf. After adjusting for rDMI, CH4RRf had a negative association with MRT in the gastrointestinal tract but not in the RR, and negative associations with fibre digestibility and measures of rumination activity. Adjusting for rDMI, CH4exhal had additionally a negative association with particle MRT in the RR and a positive association with rumen motility. Thus, higher rumen levels of CH4 (CH4exhal or CH4RRf) were associated with shorter MRT and increased motility. These findings are tentatively interpreted as a feedback mechanism in the ruminant digestive tract that aims at mitigating CH4 losses by shortening MRT at higher CH4.
authors.affiliation: 1Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty,University of Zurich,Winterthurerstr. 260,8057 Zurich,Switzerland.
authors.forename: Marie T
authors.initials: MT
authors.lastname: Dittmann
authors.affiliation: 3Sustainable Agriculture and Food Systems Research Division,Centre for Dairy Research,School of Agriculture, Policy and Development,University of Reading,PO Box 237,Earley Gate,Reading RG6 6AR,UK.
authors.forename: Kirsty J
authors.initials: KJ
authors.lastname: Hammond
authors.affiliation: 3Sustainable Agriculture and Food Systems Research Division,Centre for Dairy Research,School of Agriculture, Policy and Development,University of Reading,PO Box 237,Earley Gate,Reading RG6 6AR,UK.
authors.forename: Paul
authors.initials: P
authors.lastname: Kirton
authors.affiliation: 3Sustainable Agriculture and Food Systems Research Division,Centre for Dairy Research,School of Agriculture, Policy and Development,University of Reading,PO Box 237,Earley Gate,Reading RG6 6AR,UK.
authors.forename: David J
authors.initials: DJ
authors.lastname: Humphries
authors.affiliation: 3Sustainable Agriculture and Food Systems Research Division,Centre for Dairy Research,School of Agriculture, Policy and Development,University of Reading,PO Box 237,Earley Gate,Reading RG6 6AR,UK.
authors.forename: Les A
authors.initials: LA
authors.lastname: Crompton
authors.affiliation: 4Leibniz Institute for Zoo and Wildlife Research (IZW),Alfred-Kowalke-Str. 17,10315 Berlin,Germany.
authors.forename: Sylvia
authors.initials: S
authors.lastname: Ortmann
authors.affiliation: 5Rothamsted Research,North Wyke,Okehampton,Devon EX20 2SB,UK.
authors.forename: Tom H
authors.initials: TH
authors.lastname: Misselbrook
authors.affiliation: 6Institute of Animal Science,University of Bonn,Endenicher Allee 15,53115 Bonn,Germany.
authors.forename: Karl-Heinz
authors.initials: KH
authors.lastname: Südekum
authors.affiliation: 2ETH Zurich,Institute of Agricultural Sciences,Universitätsstr. 2,8092 Zurich,Switzerland.
authors.forename: Angela
authors.initials: A
authors.lastname: Schwarm
authors.affiliation: 2ETH Zurich,Institute of Agricultural Sciences,Universitätsstr. 2,8092 Zurich,Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Kreuzer
authors.affiliation: 3Sustainable Agriculture and Food Systems Research Division,Centre for Dairy Research,School of Agriculture, Policy and Development,University of Reading,PO Box 237,Earley Gate,Reading RG6 6AR,UK.
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Reynolds
authors.affiliation: 1Clinic for Zoo Animals, Exotic Pets and Wildlife, Vetsuisse Faculty,University of Zurich,Winterthurerstr. 260,8057 Zurich,Switzerland.
authors.forename: Marcus
authors.initials: M
authors.lastname: Clauss
mesh_terms: D000818:Animals; D002417:Cattle / Q000502:physiology*; D005243:Feces; D005260:Female; D005766:Gastrointestinal Contents; D005769:Gastrointestinal Motility / Q000502:physiology*; D006863:Hydrogen-Ion Concentration; D008409:Mastication; D008697:Methane / Q000378:metabolism*; D012417:Rumen / Q000502:physiology*
chemical_list: D008697:Methane
keywords: BCM bromochloromethane; BM body mass; CH4RRf methane in rumen fluid; CH4exhal methane emission; CP crude protein; DMI DM intake; Digestion; GIT gastrointestinal tract; MRT mean retention time; MRTsoluteRR MRT of solutes in the reticulorumen; Mean retention time; Motility; NDF neutral detergent fibre; Passage rate; RR; Rumination activity; iCH4
                  insufflation of methane; iN2
                  insufflations of nitrogen; rDMI relative DM intake; reticulorumen