For application in a multi-trait BLUP procedure, variances and covariances of first, second and third lactation records were estimated. This was done by a restricted maximum likelihood (REML) procedure with Cholesky-transformed data, including all observations. Initial values were taken from an analysis with Henderson's method 3, only using data of cows, that have been recorded for these three lactations. REML-estimates of genetic and residual variances and covariances were 10 to 25% higher than the initial values. Estimated heritabi1ities decreased about 10%, while genetic and phenotypical correlations were changed unsystematically within a narrow range. The results show, that it is worthwhile including all data available in parameter estimation to remove bias due to selection.

Henner Simianer

Proceedings of the World Congress on Genetics Applied to Livestock Production, Volume XII. Biotechnology, selection experiments, parameter estimation, design of breeding systems, management of genetic resources., , 421–426, 1986
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