The productive lifespan of dairy cows has declined dramatically under intensive selection for high milk yield, creating a welfare problem linked to production system design.
Dairy cow longevity is both a welfare indicator and a consequence of welfare conditions. Cows culled after 2-3 lactations because they are 'spent' by the metabolic demands of high-yield production have experienced a life of chronic physiological stress. Energy deficit in early lactation causes mobilization of body reserves, immune suppression, and increased susceptibility to metabolic diseases including ketosis, hypocalcemia, and displaced abomasum. Extending productive lifespan requires either reducing yield targets or improving nutritional management and health support - both have welfare and economic dimensions that the dairy industry increasingly recognizes.