title: Ruminal methane inhibition potential of various pure compounds in comparison with garlic oil as determined with a rumen simulation technique (Rusitec).
abstract: Ruminants represent an important source of methane (CH(4)) emissions; therefore, CH(4) mitigation by diet supplementation is a major goal in the current ruminant research. The objective of the present study was to use a rumen simulation technique to evaluate the CH(4)-mitigating potential of pure compounds in comparison with that achieved with garlic oil, a known anti-methanogenic supplement. A basal diet (15 g DM/d) consisting of ryegrass hay, barley and soyabean meal (1:0·7:0·3) was incubated with the following additives: none (negative control); garlic oil (300 mg/l incubation liquid; positive control); allyl isothiocyanate (75 mg/l); lovastatin (150 mg/l); chenodeoxycholic acid (150 mg/l); 3-azido-propionic acid ethyl ester (APEE, 150 mg/l); levulinic acid (300 mg/l); 4-[(pyridin-2-ylmethyl)-amino]-benzoic acid (PABA, 300 mg/l). Fermentation profiles (SCFA, microbial counts and N turnover) and H(2) and CH(4) formation were determined. Garlic oil, allyl isothiocyanate, lovastatin and the synthetic compound APEE decreased the absolute daily CH(4) formation by 91, 59, 42 and 98 %, respectively. The corresponding declines in CH(4) emitted per mmol of SCFA were 87, 32, 40 and 99 %, respectively, compared with the negative control; the total SCFA concentration was unaffected. Garlic oil decreased protozoal numbers and increased bacterial counts, while chenodeoxycholic acid completely defaunated the incubation liquid. In vitro, neutral-detergent fibre disappearance was lower following chenodeoxycholic acid and PABA treatments (- 26 and - 18 %, respectively). In conclusion, garlic oil and APEE were extremely efficient at mitigating CH(4) without noticeably impairing microbial nutrient fermentation. Other promising substances were allyl isothiocyanate and lovastatin.
authors.affiliation: ETH Zurich, Institute of Agricultural Sciences, CH-8092 Zurich, Switzerland. solivac6@gmail.com
authors.forename: Carla R
authors.initials: CR
authors.lastname: Soliva
authors.forename: Sergej L
authors.initials: SL
authors.lastname: Amelchanka
authors.forename: Stéphane M
authors.initials: SM
authors.lastname: Duval
authors.forename: Michael
authors.initials: M
authors.lastname: Kreuzer
mesh_terms: D000498:Allyl Compounds / Q000494:pharmacology*; D000818:Animals; D001419:Bacteria / Q000187:drug effects; D005285:Fermentation / Q000187:drug effects; D008697:Methane / Q000378:metabolism*; D008954:Models, Biological; D012417:Rumen / Q000502:physiology*; D013440:Sulfides / Q000494:pharmacology*
chemical_list: D000498:Allyl Compounds; D013440:Sulfides; C038491:allyl sulfide; D008697:Methane