|Document Type:||Master's Thesis|
|Name:||Crystal N. Vierhout|
|Title:||Characteristics of progeny test herds and their effects on the genetic evaluation of young sires|
|Degree:||Masters of Science|
|Committee Chair:||Dr. Bennet G. Cassell|
|Committee Members:||Dr. William D. Hohenboken|
|Dr. Michael L. McGilliard|
|Dr. Ronald E. Pearson|
|Dr. Willliam E. Vinson, Department Head|
|Keywords:||Dairy, Progeny testing, Young sires, Parent average|
|Date of defense:||February 6, 1998|
|Availability:||Release the entire work for Virginia Tech access only.
After one year release worldwide only with written permission of the student and the advisory committee chair.
Our purpose was to examine characteristics of progeny test herds and their effects on the genetic evaluation of young sires. Data for a study of response to pedigree selection by stud were evaluated from 6238 Holstein sires in four USDA animal model evaluations from January 1995 to February 1997. When data were restricted to the nine major semen producing organizations, a common intercept and slope for prediction of daughter yield deviation from pedigree merit were appropriate for milk but R2 was low at 0.14. We detected no important differences in response to pedigree selection among progeny testing methods used by major semen producing organizations. Data for a study of specific progeny test herds were 4154 Holstein progeny test herds from two AI studs and 6361 remaining herds from two states. We grouped herds into four categories, 21st Century Genetics and Genex progeny test herds, other Minnesota herds and other New York herds. Herds were described by DHI profile and average cow evaluation data. Cows with extreme yield deviations (± 3 herd standard deviations) were identified, as were daughters of progeny test bulls with extreme daughter performance relative to pedigree merit of the bull. 21st Century Genetics and Genex appear to have chosen the larger, genetically superior and better managed herds from within their regions in which to conduct their progeny testing. We were not able to predict if a bull was going to exceed or fail to meet pedigree prediction by characteristics of the progeny test herds in which he was sampled.
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