The transition period from late pregnancy through early lactation is the highest-risk welfare period for dairy cows, with metabolic diseases causing significant suffering and being the primary driver of dairy cow culling.
The transition period represents a perfect storm of physiological demand — a cow must simultaneously sustain late pregnancy, prepare for birth, initiate lactation, and restore body reserves, all while adapting to dietary changes. When this system is pushed beyond its limits by genetic selection for extreme milk production, metabolic disease follows. These diseases cause genuine suffering: a cow with ketosis is effectively in a state of starvation despite having food available; milk fever causes muscle paralysis and inability to rise. Transition management programs that prevent these diseases are welfare improvements with both ethical and economic justifications.