title: Disappearance of acetic acid from the bovine reticulorumen at basal and elevated concentrations of acetic acid.
abstract: Disappearance of acetic acid was quantified to determine whether removal of this acid from the reticulorumen is altered when ruminal acetic acid concentrations are elevated. Ruminally fistulated beef steers (n = 3 per experiment; BW = 320 +/- 9 kg) were fed eight times daily a 46% corn-based concentrate:54% mixed hay diet to meet maintenance energy requirements (3.5 kg of DM/d). In situ production of acetic acid, determined by pulsed-continuous infusion of [1-14C]acetic acid, was 530 mmol/h (CV = 12%). Disappearance from the reticulorumen (i.e., presumed absorption) was 460 mmol/h (CV = 2%) or 87% (CV = 2%) of ruminal production. Variation is described within an operational steady state. Acetic acid concentrations were increased by continuous infusion of unlabeled acetic acid into the reticulorumen. Ruminal disappearance (mmol/h) increased when this simulated production was elevated up to and exceeding in situ rates reported previously (530 to 2,700 mmol/h). These data suggest that two-thirds to three-fourths of ruminal acetate production disappeared across the reticuloruminal wall when concentration was elevated; the complement exited from the rumen with the liquid phase. The reticulorumen has an additional capacity to remove acetic acid; however, it does so with an apparent reduced efficiency at higher production rates. Liquid out-flow may affect the efficiency of reticuloruminal disappearance. Sites distal to the rumen become quantitatively important when ruminal acetic acid concentrations are increased.
authors.affiliation: Performance Enhancement Research, Upjohn Company, Kalamazoo, MI 49001.
authors.forename: J P
authors.initials: JP
authors.lastname: Peters
authors.forename: R Y
authors.initials: RY
authors.lastname: Shen
authors.forename: J A
authors.initials: JA
authors.lastname: Robinson
mesh_terms: D000042:Absorption; D000085:Acetates / Q000032:analysis / Q000378:metabolism*; D019342:Acetic Acid; D000818:Animals; D002417:Cattle; D008297:Male; D012044:Regression Analysis; D012159:Reticulum / Q000378:metabolism*; D012417:Rumen / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000085:Acetates; D019342:Acetic Acid