The three weeks before and after calving are the most challenging period in a dairy cow's annual cycle. Metabolic disease, immune failure and reproductive problems cluster in this transition period.
The transition period represents the convergence of multiple physiological challenges that each independently impair welfare. The immune suppression of late pregnancy combined with the metabolic demands of early lactation creates a window of extreme vulnerability to infectious and metabolic disease. Cows suffering from clinical ketosis experience weakness, reduced appetite and altered mentation. Milk fever causes acute collapse and potentially fatal hypocalcaemia. Metritis causes systemic infection and persistent fever. Each of these conditions represents significant suffering, and their frequent co-occurrence means that many cows experience compounding welfare deficits in the weeks after calving. Prevention through nutrition, management and monitoring is far more effective and welfare-positive than treatment of established disease.