Body condition score (BCS) is a standardised assessment of subcutaneous fat reserves in dairy cattle, scored 1-5 (thin to obese) and is one of the most powerful individual welfare indicators available. Cows losing more than 1 BCS unit in the first 60 days of lactation (excessive negative energy balance) are at dramatically increased risk of ketosis, displaced abomasum, metritis, and reduced fertility. Conversely, overconditioned cows (BCS >3.75 at calving) show higher rates of dystocia and fat cow syndrome. Target BCS at calving is 3.0-3.25; at peak lactation 2.5-3.0. Herd-level BCS monitoring at key transition points provides early warning of nutritional management failures. Precision livestock farming tools enable automated BCS assessment using 3D cameras, removing subjectivity and enabling continuous monitoring. Welfare certification protocols require documented BCS monitoring schedules and intervention thresholds.