Estimation of breeding values for functional productive life in the Slovak Holstein population

Abstract

Genetic evaluation of length of functional productive life was carried out using a Weibull proportional hazard sire-maternal grandsire model. The database included 405 624 Holstein cows with 19.24% censoring. The analyzed effects were parity × stage of lactation, within-herd standard deviations of milk production, herd × year × season interaction, change of herd size with respect to the previous year, age at first calving, and sire and maternal-grandsire effects. Parity × stage of lactation had the most important influence on functional productive life. The results of the analysis confirmed more intensive selection at the beginning of each lactation, whereby the risk ratio increased with each other lactation. Heritability of functional productive life was 0.13 on the original scale. Breeding values of sires were expressed as relative breeding values with a mean of 100 and genetic standard deviation of 12.

Keywords

• cattle
• longevity
• survival analysis
• risk ratio