An essential oil blend fed for growth performance and carcass characteristics to feedlot steers

Some essential oils (EO) are known for having antimicrobial, antiviral, antifungal, and antioxidant characteristics that may be a feedlot antibiotic alternative to replace monensin sodium (<b>M</b>) and tylosin (<b>T</b>). Four-hundred cross-bred steers (BW 368.7 ± 11.0 kg) were blocked by initial BW and cattle source and randomly assigned to 1 of 5 treatments (8 pens/trt; 10 steers/pen) to evaluate an EO blend (<b>EOB</b>). Treatments were: 1) <b>Control</b>: no additives added to the steam-flaked corn-based finishing total mixed ration (<b>TMR</b>); 2) <b>EOB</b>: proprietary essential oil blend (Ralco Nutrition, Marshall, MN) added at 3 g/d; 3) <b>EOB + M + T:</b> EOB added at 3 g/d plus M and T (Huvepharma, Peachtree City, GA) at 42.4 and 8.5 g/ton, respectively; 4) <b>M + T:</b> M and T added at 42.4 and 8.5 g/ton, respectively; and 5) <b>EOB + M</b>: EOB and M added at 3 g/d and 42.4 g/ton. Individual BW were measured on two consecutive d at the start and conclusion and every 28 d during the experiment. Equal treatment pen replicates were transported to a commercial abattoir on 160, 174, and 182 d, respectively for collecting carcass data. Initial, interim 28-d periods, and final BW were similar (<i>P</i> > 0.50) among treatments However, during the 1^st 3 28-d time-period steers fed EOB along or in combination demonstrated greater average daily gain (ADG) compared with steers fed the remaining treatments. The study remaining time-periods and overall study ADG were similar (<i>P</i> > 0.10) for all treatments. Steers fed Control consumed greater (<i>P</i> < 0.05) overall study DMI compared with steers fed M + T with steers fed the remaining treatments being intermediate but different (<i>P</i> < 0.05) or similar (<i>P</i> > 0.05). Overall, study feed efficiency was lowest (<i>P</i> < 0.05) for steers fed Control compared with steers fed the remaining treatments being similar (<i>P</i> > 0.10). Dressing percentages were greater (<i>P</i> < 0.05) for steers fed EOB compared with steers fed the remaining treatments. Steers fed M + T demonstrated the lowest (<i>P </i>< 0.05) liver abscesses compared with steers fed Control and EOB with steers fed EOB + M + T being intermediate and similar (<i>P</i> > 0.10). Feeding finishing steers an EOB improved early growth rate and dressing percentage with similar feed conversions to M and T, but did not impact liver abscess incidences.