Effect of Essential Oils or Tylosin on Performance, Liver Abscesses, Carcass Characteristics and Meat Quality in Feedlot Steers

Use of antibiotics for liver abscess prevention has been hindered by the implementation of the veterinary feed directive. Essential oils (EO) are secondary metabolites derived from plants that have antimicrobial properties that may prevent liver abscesses. Seventy-two 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 was top dressed daily at a rate of 0.45 kg/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 average pen weight of approximately 624 kg was achieved. Longissimus muscle samples were taken caudal from the last rib on the right side of each carcass for tenderness and purge loss analyses. Statistical analyses were conducted using the MIXED procedure of SAS. Performance characteristics, including weight, days on feed, ADG, DMI and gain:feed, did not differ among treatments (P≥0.37). 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. There were no differences in Warner-Bratzler shear force among treatments (P=0.32). In conclusion, inclusion of 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 data or meat quality attributes.