Lameness-Associated Changes in Milk Yield, Composition, and Inflammatory Quality Indicators in Dairy Cows under Tropical Conditions in Bangladesh

Lameness is a major welfare and economic challenge in dairy herds and is associated with reduced milk yield and compromised milk quality; however, evidence under tropical production systems such as Bangladesh remains limited. This longitudinal observational study was conducted at a commercial dairy farm in Mymensingh, Bangladesh (July 2024–June 2025) to evaluate the effects of lameness on milk yield and inflammatory milk quality indicators. Sixteen Holstein–Friesian lactating cows were enrolled, including 12 clinically lame multiparous cows and 4 healthy controls. Lameness was assessed using a standardized 1–5 locomotion scoring system. Milk yield was obtained from farm records, and milk quality traits including pH, electrical conductivity, somatic cell count (SCC), fat, protein, lactose, solid-not-fat, and total solids were analyzed using Ekomilk Horizon Unlimited. Lame cows were evaluated 7 days before diagnosis, on the diagnostic day, and 7 days after diagnosis. Multivariable linear mixed-effects models revealed a significant reduction in milk yield during lameness (15.0 ± 0.6 L/day) compared with pre-diagnosis values (19.0 ± 0.5 L/day; p<0.01), representing a 21% decline. SCC increased more than two-fold (812.8 ± 45.6 ×10³ cells/mL; p<0.001), accompanied by significant increases in electrical conductivity and pH. Lameness showed strong positive correlations with SCC (r=0.79) and conductivity (r=0.83), and a moderate negative correlation with milk yield (r=−0.62). These findings indicate that lameness is associated with systemic inflammatory changes that compromise milk production and quality under tropical conditions, highlighting the importance of early detection and welfare-based management strategies in Bangladeshi dairy systems.