Document Type

Thesis - Open Access

Award Date

1985

Degree Name

Master of Science (MS)

Department

Animal Science

First Advisor

C.A. Dinkel

Abstract

Evaluation of breeds has developed beyond simple phenotypic performance comparisons to estimation of the various genetic components, additive and nonadditive, contributed by a breed (Dickerson ,1969). Alenda et al.; Dillard et al. and Robison et al. demonstrated methods for estimating breed genetic and maternal effects in crossbred populations. Alenda and Martin extended the use of regression models to allow estimation of optimal breed combinations. This procedure, based on work by Dickerson, involves construction of a mathematical model describing performance for a trait as the sum of breed additive, breed heterotic, breed maternal and maternal heterotic effects. Crossbreeding results have been extensively reviewed by Cundiff. In his Long and Gregory review, Long and Cundiff categorized crossbreeding research as dealing with average heterosis, reciprocal differences and maximum breed differences. The objectives of the present study were 1) to evaluate preweaning performance under western South Dakota native range conditions of different cow biological types and their breed composition, as represented by straightbred Hereford (HH), Angus-Hereford cross (AH) and Simmental Hereford cross (SH) cows, and 2) to evaluate postweaning and slaughter performance of steer calves from the three cow groups. Hereford, Angus and Simmental represent beef breeds with the largest populations in the U.S. (Lawlor et al.,1984) and are also diverse biological types. Biological type commonly refers to differences in cow physiology as measured by body size and level of milk production. The. HH cow is generally characterized as medium in size with moderate milk production. Angus-Hereford cross cows are also medium in size with moderate milk production. Simmental-Hereford cows are generally large in size with a high level of milk production.

Library of Congress Subject Headings

Cattle -- Breeding
Cattle -- Genetics
Cattle -- Growth

Format

application/pdf

Number of Pages

83

Publisher

South Dakota State University

Rights

No Copyright - United State
http://rightsstatements.org/vocab/NoC-US/1.0/

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