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Relationships Between Feedlot Health, Average Daily Gain, and Carcass Traits of Angus Steers

08 January 2013

K-State University

Performance and quality are possible for beef producers if the welfare of the animal can be maintained, according to a Kansas State University report. Through having few health challenges and sufficient nutrition large, well marbled carcasses can be achieved.

Introduction

Morbidity reduces performance and quality grade, but the effects of morbidity on quality grade independent of its effect on carcass fatness are rarely documented. As feedlot cattle fatten, a greater proportion of their daily carcass gain goes to fat deposition, and greater carcass fat is consistent with greater marbling score. Higher-grading cattle are often assumed to have reduced feedlot performance. Objectives of this research were to document the impacts of various animal and non-animal factors on feedlot average daily gain, health, and carcass traits in Angus steers and to correlate quality and yield grade components of carcass with live performance.

Experimental Procedures

Angus steers (n = 17,919) fed at a single commercial feedlot in southwestern Kansas from 1997 through 2007 were used to correlate average daily gain, health, and carcass traits. Factors of interest were health status, average daily gain, quality grade, and yield grade. Health status categories were as follows: no treatment, single treatment, 2 treatments, and more than 2 treatments for respiratory or other diseases. Animals were also grouped by rate of gain, quality grade, and yield grade.

Calves had been fully preconditioned for a minimum of 30 days prior to delivery to the feedlot. Some groups were placed in backgrounding lots or on pasture at or near the ranch of origin for 60 to 150 days with their original ranch herdmates. Cattle were not commingled with calves from other ranches prior to delivery to or following arrival at the feedlot. Animals were observed daily for morbidity by feedlot personnel. All health evaluators were professional feedlot personnel.

The general manager of the feedlot visually evaluated the animals for degree of finish 60 to 80 days after administration of the terminal implant. Animals determined to be adequately finished were shipped to the packing plant. Animals not shipped with the first marketing group were evaluated for finish again 14 to 21 days later, and those meeting the criteria were shipped. A third group was subsequently shipped an additional 14 to 21 days after the second marketing group. Carcass data were evaluated by USDA personnel.

Main Effects of Number Treatments for Morbidity on Feedlot Performance and Carcass Traits for Angus Steers fed in a Single Kansas Feedlot from 1997 Through 2007

1 Treated: Includes all health treatments received while at feedlot.
2 SEM = largest standard error in the analysis.

Main Effects of Quality Grade on Feedlot Performance and Carcass Traits for Angus Steers Never Treated for Disease Fed in a Single Kansas Feedlot from 1997 Through 2007

1 SEM = largest standard error in the analysis.
2 Includes all health treatments received while at feedlot.

Effects of Yield Grade on Feedlot Performance and Carcass Traits for Angus Steers Never Treated for Respiratory Disease Fed in a Single Kansas Feedlot from 1997 Through 2007

1 SEM = largest standard error in the analysis.
2 Includes all health treatments received while at feedlot.
3 Includes all steers in the complete dataset. Animals that were treated for disease were removed from analysis of all other variables.

Correlation Coefficients (Pearson) of Various Traits in Angus Steers fed in a Single Kansas Feedlot from 1997 Through 2007 (P < 0.01)

1 Includes all health treatments received while at feedlot.
2 Prime = 4, Choice = 3, Select = 2, Ungraded = 1.

Implications

The strong inter-relationship between average daily gain, yield grade, and quality grade suggests that beef producers who are attempting to raise and market highly marbled beef do not need to choose between the genetics for performance versus genetics for marbling, but instead can select for high-performance cattle with high marbling potential. If producers reduce opportunities for nutritional stress (for example, nutrient restriction or health challenges), then ensure that the cattle are fed to their target fat content endpoint, they will more consistently achieve both excellent performance and quality grade.

January 2013

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