Influence of production, reproduction, morphology, and health traits on true and functional longevity in French Holstein cows

In the long term, resilient animals are able to maintain their normal biological processes when confronted with environmental perturbations, reducing risk of being culled. Therefore, longevity can be proposed as an indicator long-term resilience. Decisions remove a given dairy cow from herd mainly related low milk production (i.e., voluntary culling) or reasons other than involuntary culling). The aptitude delay any culling is defined true (TL), whereas functional (FL) ability avoid culling. aim study was investigate influence production, reproduction, morphology, and health traits on TL FL, identify factors for Data included 278,217 lactations 122,461 Holstein Friesian cows reared in 640 herds. length productive life, calculated time between first calving culling, censoring, used measure longevity. Survival analysis performed using proportional hazards models assuming piecewise Weibull distribution baseline hazard function, without adjustment evaluate FL TL. Insemination status, ease, mastitis, somatic cell count, displaced abomasum, udder depth had significant relationships FL. Differences estimates relative showed that often influenced decisions: farmers more prone cull even they good characteristics. identified present resilience cattle improve genetic evaluations total