Evaluation of Palm Oil as an Ingredient in Finishing Beef Cattle Diets on Performance, Carcass Characteristics, and Meat Quality, and the Composition of Spayed Heifers to Intact Heifers Fed Melengestrol Acetate on Feedlot Performance and Carcass Characteristics

Authors

• Tate S. Johnson, University of Nebraska-LincolnFollow

First Advisor

James C. MacDonald

Second Advisor

Galen E. Erickson

Committee Members

Jess Sperber, Jessie Morrill

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 Professors James C. MacDonald and Galen E. Erickson

Lincoln, Nebraska, May 2026

Comments

Copyright 2026, Tate S. Johnson. Used by permission

Abstract

Heifers represent a large proportion of cattle placed in feedlots, making pregnancy management an important consideration for maintaining performance and carcass value. Melengestrol acetate (MGA) is commonly included in feedlot diets to suppress estrus and prevent pregnancy in intact heifers during the finishing period. Alternatively, spaying has historically been utilized as a management practice to allow heifers to graze alongside breeding cattle without the risk of pregnancy. Despite its historical use, there is limited contemporary research comparing the growth performance and carcass characteristics of spayed heifers with intact heifers managed with MGA under modern feedlot conditions. Therefore, a commercial study was conducted to evaluate the effects of spaying heifers at feedlot arrival compared with intact heifers fed MGA throughout the finishing period.

In recent years, fat prices have reached historic high levels due in part to increased demand from the biofuel industry. Palm oil is the most widely produced vegetable oil in the world and does not qualify for biofuel credits in the United States. As a result, palm oil may be available at a reduced cost relative to traditional fat sources, creating interest in its potential inclusion in cattle finishing diets. However, there is limited research evaluating palm oil as an ingredient in feedlot diets. Therefore, a finishing study was conducted to evaluate different fractions of palm oil as an ingredient in cattle feed compared to no fat or tallow in performance, carcass characteristics, and beef quality measures. The three types of palm oils used consisted of crude palm oil, crude high oleic palm oil, and refined, bleached, and de-odorized palm olein.

All diets containing added fat observed an improvement in efficiency compared to the no added fat diet. No differences in carcass characteristics were observed. Additionally, no differences were observed in steak color when measured over a 7 d period or steak tenderness. This study indicates that feeding palm oil does not negatively affect cattle performance or beef quality measures. Results of the spayed heifer experiment indicate that spaying heifers into the feedlot suppresses DMI early in the feeding period which leads to reduced gain and lighter ending body weights compared to intact heifers fed MGA.

Advisors: James C. MacDonald and Galen E. Erickson