Masters Theses

Date of Award

6-1977

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Haley M. Jamison

Committee Members

Curtis Melton, William R. Backus

Abstract

The data for this study included 1,324 calf records of the Guide Lines Program maintained by the American Polled Hereford Association. The basic objective of the program and this study was to evaluate or rank sires on the production merit of their progeny. Weight per day of age (WDA) was the basis of progeny evaluation in both the preweaning and postweaning phases of this study. Chilled carcass weight, rib eye area, average fat thickness, lean percent yield, and quality grade were the basis for progeny evaluation in the carcass phase of this study. The data was subjected to least squares analysis for each phase of the study. Effects for sex, treatment, herd, sire, and age in days were found to be significant (P < .001) on preweaning WDA. A total of 34 percent of the variation in WDA was explained by the above mentioned sources of variation. A total of 70 percent of the variation due to postweaning WDA was explained by effects of sex, treatment, sire, and age in days. Each variable was found to be significant (P < .001). Sex, treatment, and sire effects were significant (P < .001) for each variable of the carcass study with one exception; sex was non-significant (P < .01) for average fat thickness. Age in days at slaughter was significant (P < .01) for quality grade and non-significant in all other cases. Duncan's Multiple Range Test was applied to the estimates of effects in all phases of the study for the purpose of sire ranking. Twelve sire groupings were provided for preweaning WDA, fifteen for postweaning WDA, twelve for chilled carcass weight, eleven for rib eye area, thirteen for average fat thickness, ten for lean percent yield, and ten for quality grade.

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