title: In vitro effects of the thiopeptide A10255 on ruminal fermentation and microbial populations.
abstract: Experiments used unadapted mixed cultures of ruminal microorganisms in batch or continuous culture fermentation to investigate the effect of a thiopeptide, A10255, on ruminal fermentation and microbial populations. After 24 h of fermentation in batch culture, addition of A10255 (.5 to 20 ppm of the culture fluid) to 0, 45, 60, and 75% concentrate diets had no effect on total VFA but increased molar proportion of propionate and decreased butyrate. The molar proportion of acetate was decreased by treatment only in the 0 and 75% concentrate diets. The increase in molar proportion of propionate by 20 ppm of A10255 was less than the increase caused by a similar concentration of monensin. The same concentration of A10255 (20 ppm) decreased ADF digestion less than 20 ppm of monensin. In continuous culture, A10255 (33 mg/kg of dietary DM) did not affect total VFA concentration, culture pH, OM digestion, or ADF digestion. Ruminal bacterial populations of total anaerobes and lactate-producing, lactate-utilizing, cellulolytic and amylolytic bacteria were unaffected by treatment. However, molar proportions of acetate, butyrate, and isovalerate were decreased, and propionate was increased, by addition of A10255.
authors.affiliation: Delaware Agricultural Experiment Station, College of Agricultural Sciences, University of Delaware, Newark 19717-1303.
authors.forename: R S
authors.initials: RS
authors.lastname: Tung
authors.forename: L
authors.initials: L
authors.lastname: Kung
authors.forename: L L
authors.initials: LL
authors.lastname: Slyter
mesh_terms: D000085:Acetates / Q000378:metabolism; D000821:Animal Feed; D000818:Animals; D000900:Anti-Bacterial Agents; D001419:Bacteria / Q000187:drug effects / Q000378:metabolism*; D002087:Butyrates / Q000378:metabolism; D020148:Butyric Acid; D002417:Cattle; D005285:Fermentation / Q000187:drug effects*; D005503:Food Additives; D008297:Male; D008985:Monensin / Q000494:pharmacology; D010455:Peptides; D010456:Peptides, Cyclic / Q000494:pharmacology*; D011422:Propionates / Q000378:metabolism; D012417:Rumen / Q000187:drug effects / Q000382:microbiology* / Q000502:physiology
chemical_list: D000085:Acetates; D000900:Anti-Bacterial Agents; D002087:Butyrates; D005503:Food Additives; D010455:Peptides; D010456:Peptides, Cyclic; D011422:Propionates; D020148:Butyric Acid; C077327:A 10255; D008985:Monensin; C029658:propionic acid