The transition period from 3 weeks before to 3 weeks after calving is the highest-risk welfare period in a dairy cow's life, with metabolic diseases causing significant morbidity and mortality in inadequately managed herds.
The transition period is a welfare crisis point where multiple concurrent challenges converge: immune suppression from calving, metabolic stress from lactation onset, and the social stress of grouping changes. Cows experiencing hypocalcemia develop the muscle weakness and inability to rise of clinical milk fever - a visible welfare emergency. The more pervasive subclinical hypocalcemia silently impairs immune function, predisposing to mastitis, retained placenta, and other postpartum diseases. The metabolic disease cluster of the transition period is largely preventable through appropriate pre-calving nutrition, calcium supplementation protocols, and fresh cow monitoring. Welfare-progressive dairy farms measure transition period disease rates as key welfare and performance indicators.