title: Monensin, virginiamycin, and flavomycin in a no-roughage finishing diet fed to zebu cattle.
abstract: Two experiments were designed to evaluate the effects of monensin, virginiamycin, and flavomycin on growth performance, carcass characteristics, apparent total tract nutrient digestibility, and rumen fermentation of zebu cattle fed a no-roughage finishing diet (whole shelled corn [WSC] based). In Exp. 1, 100 crossbred bulls (; 392 kg [SD 46.8] average initial BW) were blocked by initial BW in a 101-d feedlot trial. Five treatments were evaluated using 4 pens per treatment (5 bulls/pen): monensin at 30 mg/kg DM, virginiamycin at 25 mg/kg DM, monensin at 20 mg/kg DM plus virginiamycin at 25 mg/kg DM, flavomycin at 4.4 mg/kg DM, and monensin at 20 mg/kg DM plus flavomycin at 2.2 mg/kg DM. There were no differences in growth performance (final BW, ADG, DMI, and G:F; ≥ 0.527) and carcass characteristics (HCW, dressing percent, and 12th-rib fat; ≥ 0.235) among treatments. In Exp. 2, 7 ruminally fistulated steers were used in a 7 × 7 Latin square design to evaluate the 5 treatments of Exp. 1 and 2 additional treatments: monensin at 30 mg/kg DM plus virginiamycin at 25 mg/kg DM and monensin at 20 mg/kg DM plus flavomycin at 4.4 mg/kg DM. Experimental periods were 14 d in length (9 d of adaptation and 5 d of measurements). Apparent total tract DM, OM, CP, and NDF digestibilities were similar among treatments ( ≥ 0.224). There was no treatment effect ( ≥ 0.253) in rumen fermentation responses (ruminal pH, rumen ammonia nitrogen, VFA, and number of protozoa). In conclusion, no evidence of benefits to cattle fed a no-roughage WSC-based diet was found to support the use of monensin combined with virginiamycin or flavomycin in the doses tested herein.
authors.forename: B J M
authors.initials: BJ
authors.lastname: Lemos
authors.forename: F G F
authors.initials: FG
authors.lastname: Castro
authors.forename: L S
authors.initials: LS
authors.lastname: Santos
authors.forename: B P C
authors.initials: BP
authors.lastname: Mendonça
authors.forename: V R M
authors.initials: VR
authors.lastname: Couto
authors.forename: J J R
authors.initials: JJ
authors.lastname: Fernandes
mesh_terms: D000821:Animal Feed / Q000032:analysis; D000824:Animal Nutritional Physiological Phenomena; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D001455:Bambermycins / Q000494:pharmacology*; D001823:Body Composition / Q000187:drug effects; D002417:Cattle; D004032:Diet / Q000662:veterinary*; D004043:Dietary Fiber; D004063:Digestion / Q000502:physiology; D005285:Fermentation; D041981:Gastrointestinal Tract / Q000187:drug effects; D008297:Male; D008985:Monensin / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D061209:Proton Ionophores / Q000494:pharmacology; D012417:Rumen / Q000378:metabolism; D014769:Virginiamycin / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D004043:Dietary Fiber; D011500:Protein Synthesis Inhibitors; D061209:Proton Ionophores; D014769:Virginiamycin; D001455:Bambermycins; D008985:Monensin