Monensin, virginiamycin, and flavomycin in a no-roughage finishing diet fed to zebu cattle1

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.

Effect of increasing monensin sodium levels in diets with virginiamycin on the finishing of Nellore cattle

“…No effect was observed in the carcass traits when the additives were combined. This result agrees with the study of Lemos et al (2016) which observed no effect of VM and MON association on carcass traits. Similarly, Silva et al (2004) suggested that the combination of VM and ionophores may have a synergistic effect on ADG, but without exerting substantial effects on carcass traits.…”

“…This result agrees with the study of Lemos et al . () which observed no effect of VM and MON association on carcass traits. Similarly, Silva et al .…”

Carcass traits of sheep fed banana pseudostem hay

“…In experiments with feedlot calves, no differences were found for hot carcass weight or hot carcass yield of animals supplemented with virginiamycin (MONTANO et al, 2015;LEMOS et al, 2016;NAVARRETE et al, 2017). In a trial with feedlot sheep receiving 60: 40 concentrate: roughage ratio diets, treatments using banana pseudostem hay as roughage provided better results compared to those with Cynodon sp.…”

Fatty acid profile and carcass traits of feedlot Nellore cattle fed crude glycerin and virginiamycin

“…Rogers et al (1995) demonstrated, in a series of dose-response trials (19 mg to 27 mg VM/kg DM) with steers and heifers, that VM enhanced the average daily gain (4.6%), and gain to feed ratio (3.6%). However, studies describing the effect of VM on meat traits are still limited in beef cattle (Lemos et al, 2016;Salinas-Chavira et al, 2009), and, to our knowledge, no previous study has described fatty acid profiles of meat from feedlot Nellore cattle supplemented with VM. The utilization of microbes that are directly fed to livestock, such as Megasphaera elsdenii, could be an alternative for antibiotics such as VM, by reducing ruminal accumulation of lactate (Counotte, Prins, Janssen, & Debie, 1981).…”