The Detection of Morbidity using a Remote Sensing Ear Tag on Newly Received Steers and Feedlot Performance and the Effects of Feeding Experior and Optaflexx on Carcass Characteristics and Meat Tenderness in Beef Steers

Authors

• Lauryn O. Smidt, University of Nebraska-LincolnFollow

First Advisor

James C. MacDonald

Date of this Version

5-2026

Document Type

Thesis

Citation

A thesis presented to the faculty of the Graduate College at the University of Nebraska in partial fulfillment of requirements for the degree of Master of Science

Major: Animal Science

Under the supervision of Professor James C. MacDonald

Lincoln, Nebraska, May 2026

Comments

Copyright © 2026, Lauryn O. Smidt. Used by permission

Abstract

Two experiments were conducted to evaluate the effects of remote sensing health technology and growth-promoting feed additives on feedlot cattle performance, health outcomes, and carcass characteristics. In the first study, 638 crossbred steers (initial BW = 270 kg; SD = 18.6 kg) were used in a randomized block design to assess the effectiveness of a remote sensing ear tag (RST; HerdDogg, Seward, Nebraska) versus conventional pen-rider observation (PR) for detecting morbidity during a 35-d receiving period and subsequent 180-d finishing period. No differences were detected between PR and TAG for ending BW, average daily gain (ADG), dry matter intake (DMI), or feed efficiency during receiving (P > 0.53). However, a greater proportion of RST steers were treated at least once (42.2% vs. 31.7%; P = 0.01) and treated multiple times (P ≤ 0.10). Despite increased pulls, performance, and carcass outcomes during finishing were unaffected (P > 0.36), indicating that remote sensing increased treatment frequency without improving performance.

In the second study, 621 crossbred steers (initial BW = 308 kg; SD = 16.1 kg) were fed either Lubabegron (LUB; Experior; Elanco Animal Health; Greenfield, Indiana) or Ractopamine Hydrochloride (RAC; Optaflexx; Elanco Animal Health; Greenfield, Indiana) at 36 mg/steer daily or 300 mg/steer daily, respectively. Steers fed LUB had greater ADG, improved feed efficiency by 5%, and produced carcasses 10 kg heavier than RAC-fed steers (P < 0.01). However, LUB-fed steers had reduced marbling scores (P < 0.01) and lower proportions of USDA Prime, high choice, and mid choice carcasses (P < 0.01). Meat quality assessment of strip loins (n = 160) showed RAC-fed steers produced more tender meat at 7-d postmortem (P < 0.01), with greater redness and yellowness values (P ≤ 0.03). Overall, remote sensing tags improved morbidity detection but did not enhance performance, whereas feeding LUB increased carcass weight but had reduced marbling and tenderness compared to RAC.

Advisor: James C. MacDonald