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 (M) and tylosin (T). 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 (EOB). Treatments were: 1) Control: no additives added to the steam-flaked corn-based finishing total mixed ration (TMR); 2) EOB: proprietary essential oil blend (Ralco Nutrition, Marshall, MN) added at 3 g/d; 3) EOB + M + T: EOB added at 3 g/d plus M and T (Huvepharma, Peachtree City, GA) at 42.4 and 8.5 g/ton, respectively; 4) M + T: M and T added at 42.4 and 8.5 g/ton, respectively; and 5) EOB + M: 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 (P > 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 (P > 0.10) for all treatments. Steers fed Control consumed greater (P < 0.05) overall study DMI compared with steers fed M + T with steers fed the remaining treatments being intermediate but different (P < 0.05) or similar (P > 0.05). Overall, study feed efficiency was lowest (P < 0.05) for steers fed Control compared with steers fed the remaining treatments being similar (P > 0.10). Dressing percentages were greater (P < 0.05) for steers fed EOB compared with steers fed the remaining treatments. Steers fed M + T demonstrated the lowest (P < 0.05) liver abscesses compared with steers fed Control and EOB with steers fed EOB + M + T being intermediate and similar (P > 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.