title: Effect of the combination of monensin and isoacids on rumen fermentation in vitro.
abstract: Effects of isoacids, monensin, or a combination of them on fermentation by mixed rumen bacteria were investigated using a continuous culture technique. The culture was allowed to stabilize for 4 d before treatments were imposed. Comparisons between treatments were made on d 11 and 12 of the culture. Isoacids (equal proportions of isobutyric, 2-M-butyric, isovaleric, and valeric acids) at 15 mg/dl of culture media increased acetate (6.17 vs. 5.48 meq/dl) and total VFA production (8.93 vs. 7.87 meq/dl) compared with that of controls. Monensin at 150 micrograms/dl reduced acetate (3.74 vs. 6.02 meq/dl) and VFA (6.84 vs. 8.54 meq/dl) but increased propionate (2.28 vs. 1.74 meq/dl) relative to control. The combination of isoacids and monensin increased acetate relative to monensin alone (5.24 vs. 3.74 meq/dl) but did not alter the effect of monensin on propionate concentration (2.32 vs. 2.28 meq/dl). It is concluded that monensin decreases acetate production by 35% and when isoacids are added to the cultures containing monensin, acetate production is restored.
authors.affiliation: Michigan State University, East Lansing 48824.
authors.forename: P
authors.initials: P
authors.lastname: Kone
authors.forename: P F
authors.initials: PF
authors.lastname: Machado
authors.forename: R M
authors.initials: RM
authors.lastname: Cook
mesh_terms: D000818:Animals; D002087:Butyrates / Q000494:pharmacology; D020148:Butyric Acid; D002417:Cattle / Q000382:microbiology*; D005232:Fatty Acids, Volatile / Q000494:pharmacology*; D005260:Female; D005285:Fermentation / Q000187:drug effects*; D045782:Hemiterpenes; D058610:Isobutyrates; D008985:Monensin / Q000494:pharmacology*; D010421:Pentanoic Acids / Q000494:pharmacology; D012417:Rumen / Q000382:microbiology*
chemical_list: D002087:Butyrates; D005232:Fatty Acids, Volatile; D045782:Hemiterpenes; D058610:Isobutyrates; D010421:Pentanoic Acids; D020148:Butyric Acid; C008216:isovaleric acid; C020380:isobutyric acid; D008985:Monensin; C038780:n-pentanoic acid