title: In vitro gas production kinetics and short-chain fatty acid production from rumen incubation of diets supplemented with hop cones (Humulus lupulus L.).
abstract: The aim of this study was to assess the effects of hop cones (Humulus lupulus L.) from two varieties Aurora and Dana, differing in their α- and β-acid contents, on rumen microbial activity measured with in vitro gas production kinetics and short-chain fatty acids (SCFA) production. Hop cones were added to the total mixed dairy cow ration (CONT) in concentrations simulating a cow's daily intake of 50, 100 and 200 g of hop cones - the concentrations of hop cones expressed on a substrate basis were 43, 82 and 153 mg/g of substrate. Substrates were anaerobically incubated in glass syringes, and gas production kinetic parameters were determined by fitting data with the Gompertz model. Gas produced after 24 h (Gas24), maximum fermentation rate (MFR) and time of maximum fermentation rate (TMFR) were calculated from the estimated gas production kinetic parameters. After 24 h of incubation, the fermentation liquids of each substrate were taken for the determination of SCFA. Increasing the hop cone concentration decreased the total potential gas production, Gas24, MFR and shortened TMFR. The highest hop cone concentration significantly decreased acetic and butyric acid productions and total SCFA production after 24 h of incubation, but not propionic acid production, resulting in a decreased ratio between acetic acid and propionic acid.
authors.affiliation: 1Department of Animal Science, Biotechnical Faculty,University of Ljubljana,Groblje 3,SI-1230 Domžale,Slovenia.
authors.forename: A
authors.initials: A
authors.lastname: Lavrenčič
authors.affiliation: 1Department of Animal Science, Biotechnical Faculty,University of Ljubljana,Groblje 3,SI-1230 Domžale,Slovenia.
authors.forename: A
authors.initials: A
authors.lastname: Levart
authors.affiliation: 2Slovenian Institute of Hop Research and Brewing,Cesta Žalskega tabora 2,SI-3310 Žalec,Slovenia.
authors.forename: I J
authors.initials: IJ
authors.lastname: Košir
authors.affiliation: 2Slovenian Institute of Hop Research and Brewing,Cesta Žalskega tabora 2,SI-3310 Žalec,Slovenia.
authors.forename: A
authors.initials: A
authors.lastname: Čerenak
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D000821:Animal Feed / Q000032:analysis; D000818:Animals; D002087:Butyrates / Q000378:metabolism; D002417:Cattle / Q000502:physiology*; D019587:Dietary Supplements; D005232:Fatty Acids, Volatile / Q000378:metabolism*; D005260:Female; D005285:Fermentation; D027582:Humulus; D007700:Kinetics; D011422:Propionates / Q000378:metabolism; D012417:Rumen / Q000378:metabolism / Q000382:microbiology
chemical_list: D002087:Butyrates; D005232:Fatty Acids, Volatile; D011422:Propionates; C029658:propionic acid; D019342:Acetic Acid
keywords: microbial activity