Congress on Genetics Applied to Livestock Production Approximate multivariate genetic evaluation of functional longevity and type traits in Austrian Fleckvieh cattle

To optimize the subindex for functional longevity in Austrian Fleckvieh, an approximate multivariate approach was analyzed. Genetic parameters for functional longevity and five type traits were estimated multivariately based on yield deviations. Genetic parameters differed slightly from the ones used in the routine evaluation. Indices and reliabilities computed in a full multivariate approach were defined as reference and compared with three other approaches: (1) is based on approximate genetic correlations and selection index theory; (2) is an approach using multivariate estimates of genetic correlations; (3) is a univariate approach ignoring auxiliary traits. Rank correlations of indices based on different approaches were above 0.90, except for those based on univariate EBVs. Variances of indices were lower for the multivariate approach when reliabilities were low. Results indicate that reliabilities and variances of indices are overestimated for the approaches that are based on selection index theory.