Effects of within herd variation on the relationship between genetic evaluations and performance of offspring

1,032,438 Jersey and 1,162,578 Holstein official Dairy Herd Improvement Association (DHIA) records from 20,380 and 34,000 herd-years, respectively, were used to compute herd-year means and within herd-year standard deviations for individual mature equivalent (ME) milk, fat, and fat percent. These herd-year means and within standard deviations were used to stratify records into five classes. Regressions for individual daughter's modified contemporary deviation (MCD) on sire's predicted difference (PD) were calculated for each class. The within herd-year standard deviations were also used in some of the six different MCD calculations used to compute six different cow indexes (CI) for each cow and trait. The six MCDs calculated were either the current deviation, log adjusted deviation, or the deviation standardized to a constant variance in combination with either the current correction for contemporaries merit or an adjusted correction. The six different CI for each trait were compared by how accurately they predicted the son's MCD trait and the daughter's MCD trait.

Name thesis:degree_name

Master of Science

Level thesis:degree_level

masters

Discipline thesis:degree_discipline

Dairy Science

Department dc:contributor.department

Dairy Science

Grantor dc:publisher

Virginia Tech

Year dc:date.issued

1987

Author dc:creator

• Meinert, Todd Richard

Chair dc:contributor.committeechair

• Pearson, Ronald E.

Committee members dc:contributor.committeemember

• Cassell, Bennet G.
• Vinson, William E.

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Dc Identifier Other

etd-03122013-040052

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/41548