This Is AuburnElectronic Theses and Dissertations

Effects of Ractopamine Hydrochloride on Color Attributes and Meat Quality in Yearling Heifers Across Days on Feed




Hunter, Erin

Type of Degree



Animal Sciences


Recent research with the use of β-agonists has been inconclusive from a meat quality standpoint. Therefore, the objective of this study is to evaluate the inclusion of RAC across 5 DOF in 72 crossbred yearling heifers and how it effects meat quality. Heifers were individually fed twice a day at the Auburn University Beef Cattle Evaluation facility. Heifers were divided based on initial height and weight, and randomly assigned to one of the following DOF groups: 79 (n = 16), 100 (n = 16), 121 (n = 16), 142 (n = 16), or 163 (n = 7). Within these 5 groups, heifers were randomly assigned to a treatment of either 300 mg∙hd-1∙d-1 RAC-HCl (RAC; Elanco Animal Health, Greenfield, IN) for the final 35 d prior to harvest or a control group (CON; 0 mg∙hd-1∙d-1 RAC). Twenty-four hours postmortem, boneless loins were removed from the right side of each animal, vacuum-packaged, and aged for 21 d in the cooler (2oC). After 21 d, 7 strip steaks (2.54 cm thick) were cut for sensory analysis, WBSF, and lipid oxidation analysis. The main effect of RAC had no effect (P > 0.05) on meat quality. Hot carcass weight was lowest (P < 0.05) for DOF group 79 compared to other DOF treatment groups. Backfat thickness and KPH was highest (P < 0.05) in DOF groups 121 and 142. Intermediate fiber area was highest (P < 0.05) for DOF group 121. The percentage of red fibers was highest (P < 0.05) for DOF group 121. Compared to all other treatments, DOF group 163 RAC steaks were less tender for initial and sustained tenderness. RAC supplementation had no effect on carcass characteristics and there were no deleterious effects on meat quality factors by the addition of RAC into the diet.