title: Effects of extracts of Humulus lupulus (hops) and Yucca schidigera applied alone or in combination with monensin on rumen fermentation and microbial populations in vitro.
abstract: BACKGROUND
  β-Acids in hops (Humulus lupulus) and saponins in yucca (Yucca schidigera) have been found to possess antimicrobial properties similar to that of monensin and could be an alternative to in-feed antibiotics. The effects of monensin (MON) and ethanol extracts of hops (HE) and Y. schidigera (YE) alone and in combination with MON were assessed on ruminal microbial composition and fermentation in vitro of a barley-based diet.
  
  
  RESULTS
  All treatments decreased (P < 0.05) CH4 production (per unit of dry matter), microbial protein (mg), and NH3 -N accumulation. All treatments reduced (P < 0.01) the acetate:propionate (A:P) ratio and molar proportions of butyrate, but increased (P < 0.01) those of propionate, whereas those of acetate decreased (P < 0.001) with addition of MON (10 µg mL(-1)) and combined with HE or YE. Methane produced per unit of true digested dry matter decreased (P < 0.001) with all treatments except YE. Monensin reduced (P < 0.001) proportions of 16S rRNA copies of Ruminococcus flavefaciens, but increased (P < 0.01) those of Selenomonas ruminantium. Hops extract alone or combined with MON reduced (P < 0.01) proportions of R. flavefaciens but combined with MON tended (P < 0.1) to increase those of S. ruminantium. Yucca extract combined with MON increased (P < 0.01) the proportions of R. flavefaciens and S. ruminantium. All treatments except MON (2.5 µg mL(-1)) reduced (P < 0.01) the relative abundance of methanogens.
  
  
  CONCLUSIONS
  Hops extract and YE altered rumen microbes and fermentation in a manner similar to MON with many responses being additive when applied in combination.
authors.affiliation: Lethbridge Research Centre, Agriculture and Agri-Food Canada, Lethbridge, Alberta, Canada.
authors.forename: Nelmy
authors.initials: N
authors.lastname: Narvaez
authors.forename: Yuxi
authors.initials: Y
authors.lastname: Wang
authors.forename: Tim
authors.initials: T
authors.lastname: McAllister
mesh_terms: D019342:Acetic Acid / Q000378:metabolism; D000143:Acids / Q000494:pharmacology; D000641:Ammonia / Q000378:metabolism; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001419:Bacteria / Q000187:drug effects* / Q000235:genetics; D001426:Bacterial Proteins / Q000378:metabolism; D020148:Butyric Acid / Q000378:metabolism; D004032:Diet; D005285:Fermentation; D001467:Hordeum / Q000378:metabolism*; D027582:Humulus; D000432:Methanol / Q000378:metabolism; D064307:Microbiota / Q000187:drug effects; D008985:Monensin / Q000494:pharmacology*; D010936:Plant Extracts / Q000494:pharmacology*; D011422:Propionates / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000378:metabolism; D012417:Rumen / Q000378:metabolism*; D012418:Ruminants; D045857:Ruminococcus / Q000187:drug effects / Q000235:genetics; D012503:Saponins / Q000494:pharmacology; D020357:Selenomonas / Q000187:drug effects / Q000235:genetics; D027623:Yucca
chemical_list: D000143:Acids; D000900:Anti-Bacterial Agents; D001426:Bacterial Proteins; D010936:Plant Extracts; D011422:Propionates; D012336:RNA, Ribosomal, 16S; D012503:Saponins; D020148:Butyric Acid; D000641:Ammonia; D008985:Monensin; C029658:propionic acid; D019342:Acetic Acid; D000432:Methanol