In earlier Mexican Holstein genetic evaluations for milk production several problems were detected : 1) the use of age-month correction factors estimated without considering differences among geographical regions and using a sire model ; 2) the possible existence of heterogeneity of variances for milk production across fixed effects was not considered ; 3) the possible existence of a genotype-environment interaction among regions was not evaluated ; and 4) the lack of genetic parameters for longevity, conformation and milk components traits limited the development of a comprehensive selection criteria for Holstein cattle in Mexico. In this study new age-month correction factors for milk production were estimated. The existence of heterogeneity of genetic additive and residual variances was studied using different classification approaches. Also, the presence of a genotype-environment interaction was evaluated. With the aim of developing a system for Holstein cattle evaluation for Mexico, genetic and phenotypic parameters among conformation, longevity and milk production traits were estimated and some multi trait selection indexes were evaluated.

M. Valencia, F. Ruiz, H. Montaldo

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume 2002. Session 1, , 1.77, 2002
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