Evaluating the effects of an essential oil feed additive on production efficiency, carcass attributes, and beef steak quality in feedlot steers

Abstract

The antimicrobial and antioxidant properties of essential oil (EO) present them as potential alternatives to conventional feed additives in feedlot cattle. Therefore, the objective of this research was to evaluate the effects of a dietary essential oil blend (EOB), administered alone or in combination with monensin (M) and tylosin (T), on finishing steer growth performance, carcass characteristics, and subsequent meat quality attributes of longissimus lumborum steaks. Four hundred cross-bred steers (initial BW 368.7 ± 11.0 kg) were utilized in a randomized complete block design and assigned to one of five dietary treatments: 1) Control (no additives); 2) EOB (3 g/d); 3) EOB+M+T; 4) M+T; or 5) EOB+M. Performance and carcass data were collected for all steers. Following harvest, two striploins per pen from a subset of pens (n=4/treatment) from the Control, EOB, and M+T treatments were collected, aged for 21 days, and analyzed for a suite of meat quality characteristics. While the overall average daily gain (ADG) was similar (P > 0.10) among treatments for the entire feeding period, steers fed EOB-supplemented diets demonstrated periods of improved early growth. Steers fed Control, and EOB had greater (P < 0.05) overall dry matter intake (DMI) than those fed M+T. Feed efficiency was lowest (P < 0.10) for Control steers compared to all other treatments. Regarding carcass characteristics, steers supplemented with EOB had a greater (P < 0.10) dressing percentage (64.3%) compared to all other treatments. Conversely, the incidence of liver abscesses was lowest (P < 0.10) for steers fed M+T compared to Control, EOB, and EOB+M treatments. In the subsequent meat quality analysis, dietary treatments were similar (P > 0.05) on instrumental color, pH, lipid oxidation, metmyoglobin reducing activity, microbial populations, shear force, or fatty acid profiles of steaks aged for 21 days. These results indicate that supplementing an EOB in finishing steer diets can improve early growth rates and dressing percentage, with feed conversion similar to ionophore-based treatments. However, the EOB did not reduce the incidence of liver abscesses. Furthermore, the EOB inclusion did not influence the quality or shelf-life characteristics of the final meat product. This suggests that essential oil blends may serve as a viable production enhancer in beef finishing systems without altering beef quality attributes. However, they may not fully replace the liver abscess control provided by tylosin.