Typescript. / Thesis (Ph. D.)--University of Hawaii, 1970. / Bibliography: leaves [253]-258. / xiii, 258 l graphs, tables, maps

The forty-eight animals that won first, second, third, and fourth places in the twelve regular classes at the 1913 International Live Stock Show are taken as basis for this study. Each and every one of these animals are representative of the highest of Hereford standards. While it is true that these forty-eight animals do not represent the entire breed, they do representt the highest type of Herefords that is being produced in the United States, and for a sire to be rated among the foremost he should be closely related to these leading animals. / Master of Science

No description available.

Call number: LD2668 .T4 1984 H633 / Master of Science

Graduation date: 1971

Two data sets of first-parity classification records were analyzed to examine heterogeneity of variances for conformation in the U. S. Holstein population. Data set I included records for final score and linear descriptive traits on cows scored from 1983 through 1986. Results indicated a strong negative correlation (r = -.59) between within-herd standard deviation for final score and herd-mean final score. Regression analysis suggested a curvilinear decrease (concave up) in within-herd standard deviation for final score with increasing herd-mean final score. Within-herd standard deviations for linear descriptive traits demonstrated a linear decline with increases in herd-mean final score. Daughter contemporary deviation for final score was regressed on her sire’s Predicted Difference type within 25 mean/standard deviation subclasses. Response to selection was greatest in high-mean/variance herds and least in low-mean/variance herds. Restricted maximum likelihood estimates of sire and error variance were approximated within each of 5 herd-mean subclasses of the data. Regressions revealed environmental variance for final score decreased curvilinearly (concave up) with increasing herd-mean final score. Genetic variance declined linearly. Heritability demonstrated no significant trend. For most linear traits, environmental variance decreased linearly with increasing herd-mean final score. Linear decreases in genetic variance were noted for foot angle, udder depth and rump angle, Heritability had positive trends for body depth, angularity, rear udder height, udder support, and teat placement. Data set II included first-parity final scores on cows classified from 1967 to 1986. Relationships estimated between herd mean and within-herd variance for final score on recent data were confirmed. Positive trends over time were noted for: within-herd standard deviation for final score, the antagonistic relationship between herd mean and within-herd variance, the antagonistic relationship between average Predicted Difference type and within-herd variance, and average herd-mean Predicted Difference type. Results indicate selection for final score was occurring in the population. Differences in within-herd selection differentials accounted for 24% of the differences in within-herd variance for final score. / Ph. D.