A new model for the genetic evaluation for longevity in German Holsteins

Helge Täubert, Johannes Heise, Friedrich Reinhardt, Reinhard Reents

Abstract


The genetic evaluation for longevity in German Holsteins was based on a proportional hazards model (PHM) for about 20 years. A new evaluation was developed based on a linear multiple trait model. In this model the first three lactations are separated into 3 stages each, days in milk 0 - 49, 50- 249 and 250 – consecutive calving. Therefore, 9 genetically correlated survival traits are modelled. Survival of each stage is coded as 1 (survived) or 0 (disposed). Breeding values of the 9 stages are combined to an index breeding value of total survival.

Advantages of the new model are, among others, consideration of information on survival in early lactations and a better comparison of daughter survival within lactation and stage of lactation. Accuracies of early predictors and stability of EBVs in the new model are clearly better than with the current PHM. Overestimation of young bulls’ proofs, as observed in the PHM, cannot be seen from the linear model.


Keywords


dairy cattle; longevity; estimation of breeding values

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