Length of productive life and longevity in dairy cows - heritability of traits for longevity and their genetic correlations with milk performance and functional traits

Black pied German Holstein cows actually achieve a mean age at culling of 5.4 years. In dairy farming length of productive life has a crucial impact on the economic out-come and thus, breeding for long living and highly performing cows seems to be essential for profitable livestock production systems. In this review, heritability estimates of the traits longevity, length of productive life, functional longevity and stayability will be discussed in the context along with the different statistical models employed. Heritabilities for the length of productive life are at 0.04-0.14 and for functional longevity at 0.04-0.11 when all culling data were available. Survival analysis with Weibull distributions are employed for censored data or multitrait evaluations using each section of life as a separate trait. Overestimation of heritabilities could be observed when censored data were used. Length of productive life is genetically highly correlated with milk performance traits, while the functional longevity shows only small or negative genetic correlations with milk performance traits. Type and health traits only show small to moderate genetic correlations with length of productive life and functional longevity. Genetic progress for an increasing longevity may be smaller in comparison with milk performance due to the smaller heritabilities and the long time until data are available. Higher genetic progress may be facilitated through genomic evaluations of breeding values and the use of progeny with the opportunity of having completed at least five lactation numbers.