Masters Theses

Date of Award

6-1975

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Don O. Richardson

Committee Members

J. B. McLaren, M. J. Montgomery

Abstract

The purposes of this study were to use type and progeny summaries of dairy sires born prior to 1960 to determine their usefulness toward increasing longevity and production in the Guernsey, Holstein, and Jersey breeds. Data for this study were obtained from USDA-DHIA Sire Summaries for production, and from official type summaries for classification data over a six year period (1967 to 1973). The analysis of the three breeds indicates negative correlations of -0.37, -0.25, and -0.40 between the number of records and. percent of incomplete records for Guernsey, Holstein, and Jersey breeds, respectively. Records per daughter had 0.12, 0.24, and -0.01 correlations with average score in the Guernsey, Holstein and Jersey breeds, respectively. Milk and fat were negatively correlated with type in the Holsteins and Jerseys. The Guernsey, Holstein, and Jersey breeds should be primarily concerned with their selection programs to increase longevity. Since an increase in longevity would require fewer heifer replacements, it would be very economical for dairymen to consider those sires with more records per daughter, along with high predicted differences for milk and fat.

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