N. GENGLER,* G. R. WIGGANS,and J. R.
*National Fund for Scientific Research, B-1000 Brussels, Belgium, and Animal Science Unit, Gembloux Agricultural University, B-5030 Gembloux, Belgium
Animal Improvement Programs Laboratory, Agricultural Research Service, USDA, Beltsville, MD 20705-2350
ABSTRACT A system to calculate genetic evaluations based on an animal model was developed for final score (single-trait model) and 15 linear type traits (multitrait model) of Ayrshires, Brown Swiss, Guernseys, Jerseys, and Milking Shorthorns. (Co)variance components were estimated from appraisals that were scored during 1988 and later and that included all linear traits. The model for (co)variance components included fixed effects for interactions of herd, appraisal date, and parity; parity and appraisal age; and parity and lactation stage. Random effects were included for permanent environment, animal, and residual. A canonical transformation was used with approximate diagonalization. Data for estimating breeding values included appraisals from 1980. Effects for appraisal age and lactation stage were defined within appraisal year group. The model for calculation of breeding values also included a random effect of interaction between herd and sire. Solutions for appraisal age from a preliminary analysis were smoothed with a quadratic curve to generate additive age adjustments by month for appraisal age, parity, and appraisal year group. Correlations of solutions from this model and from the former USDA sire model for bulls that were born during 1975 or later and that had 20 daughters were highest (generally >=0.90) for Guernseys and were lowest (generally <=0.80) for Milking Shorthorns. The evaluation system was implemented in February 1998 and was extended to Red and Whites.
Key Words: linear type, final score, genetic evaluation, animal model
1999 J. Dairy Sci. 82:1350
© 1999, by the American Dairy Science Association. All rights reserved.