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Document Type

Thesis - University Access Only

Award Date

2001

Degree Name

Master of Science (MS)

Department

Animal Science

First Advisor

Donald Boggs

Abstract

Data from 749 steers enrolled in South Dakota State University's Calf Value Discovery (CVD) Program (1998, 1999, 2000) were used to investigate factors affecting health and value of feedlot steers. This analysis was conducted to evaluate how ranch of origin management (ROM) and feedlot health impact economic value and the occurrence of respiratory tract lesions (RTL) in feedlot steers at harvest. Preliminary observations from 1998 and 1999 data suggested ranch of origin management and health were associated with the occurrence of RTL in feedlot steers at harvest and net value. Groups of at least five steers from 82 owners entered the feedlots in November 1998, November 1999, and October 2000. Producers completed a survey at feedlot entry, which described health and management practices at the ranch of origin. Steers were fed in a single pen and were marketed on a grade and yield basis. At harvest, lungs were examined for evidence of RTL. Steers were classified based on the type and severity of lesions and then were categorized as having no lesions or having lesions. Logistic regression of SAS was employed to model factors affecting the occurrence of RTL at harvest. An ordinary least squares regression procedure was employed to analyze the data for the outcome net value. The dependent variable, net value was defined as: carcass revenue - feedlot cost. Overall fit of the regression model for net value was indicated by coefficient of determination R2 =0.7185. Analysis of results for health and ROM factors affecting RTL (Table 1) and net value (Table 2) are provided in the tables below. Factors in the table are defined as: a) creep - if the steer was creep fed prior to weaning at the ranch of origin; b) respiratory disease - if steer was treated for respiratory disease in the feedlot; c) prewean - days weaned prior to feedlot entry were categorized into seven categories: category 1=0 to 7 d, category 2=8 to 14 d, category 3=15 to 21 d, category 4=22 to 28 d, category 5=29 to 35 d, category 6=36 to 42 d, and category 7=>43 d; and d) weaning viral - a viral vaccination administered at weaning at the ranch of origin. Owner was found to be significant (P<.001) in both models. These data suggest ranch of origin management factors impact the occurrence of RTL, as well as net value of feedlot steers at harvest. A more thorough understanding of these factors could reduce the occurrence of RTL, improve feedlot performance and carcass quality, and may help producers increase the net value of their product.><.001) in both models. These data suggest ranch of origin management factors impact the occurrence of RTL, as well as net value of feedlot steers at harvest. A more thorough understanding of these factors could reduce the occurrence of RTL, improve feedlot performance and carcass quality, and may help producers increase the net value of their product.

Library of Congress Subject Headings

Beef cattle -- Feeding and feeds
Beef cattle -- Health
Beef cattle -- Carcasses
Beef -- Quality

Format

application/pdf

Publisher

South Dakota State University

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