Effect of essential oils on performance, liver abscesses, carcass characteristics and meat quality in feedlot steers

Essential oils (EO) are secondary metabolites derived from plants that have antimicrobial properties which may prevent liver abscesses in feedlot cattle. Seventy-two Angus × Simmental crossbred steers (358 ± 7.6 kg initial BW) were blocked by weight and breed composition and randomly allocated to 3 treatments (4 pens/treatment, 6 steers/pen) to determine the effects of an EO blend or tylosin on performance, liver abscesses, carcass characteristics and meat quality. Treatments were delivered in a premix with dried distillers grains with solubles (DDGS) that were top-dressed daily at a rate of 454 g/steer daily (CON: no additives, TYL: 90 mg/steer daily tylosin, and EO: 1 g/steer daily essential oil blend). The basal diet contained (DM basis) 54% cracked corn, 26% DDGS, 14% corn silage and 6% supplement. Steers were slaughtered at two different time points when a target weight of 624 kg was achieved. Longissimus lumborum muscle samples were taken caudal from the last rib on the right side of each carcass for pH, tenderness, purge and cook loss, and lipid oxidation analyses. Statistical analyses were conducted using the MIXED procedure of SAS. Performance characteristics, including weight, ADG, DMI and gain:feed, did not differ among treatments (P ≥ 0.54). Similarly, no differences were observed in carcass characteristics (P ≥ 0.19). Steers fed EO tended to have an increased prevalence of liver abscesses in the A category (P = 0.10) as compared to CON and TYL. Purge loss was decreased (P = 0.02) for EO steaks compared to CON and TYL, but there were no differences in cook loss, Warner-Bratzler shear force, pH or lipid oxidation among treatments (P ≥ 0.32). In conclusion, an EO blend or tylosin in the diet of finishing steers did not affect growth performance or carcass characteristics, and little difference was observed in liver abscess incidence or meat quality attributes.