Effects of Free‐Stall Floor Improvement on Foot Health, Lying Behavior, and Hair Cortisol Concentrations in Dairy Cows

ABSTRACT

Inadequate stall flooring compromises both welfare and productivity in dairy cows, and hair cortisol concentration has recently been proposed as a biomarker of chronic stress. This study investigated the effects of replacing concrete stall floors with those covered by rubber comfort mattress on leg health, lying behavior, body condition, and hair cortisol concentrations in Holstein dairy cows. Seven cows were monitored before and for 3 months after stall floor improvement. Body condition score (BCS), hock and coronet scores, and hair cortisol concentrations were recorded monthly, and lying behavior was analyzed from video recordings. After stall floor replacement, BCS increased significantly at 3 months, and coronet scores decreased at 2 and 3 months compared with those before stall floor replacement. Hair cortisol concentrations remained unchanged overall but showed a significant positive correlation with hock score ( r  = 0.51, p  < 0.05). Total lying time and lying rate tended to increase compared with before stall floor improvement. These findings indicate that stall floor improvement enhanced cow comfort and reduced hoof inflammation, although more time is required for hock lesions to recover. Hair cortisol may serve as a biomarker reflecting accumulated chronic stress, whereas lying behavior reflects a more immediate response to stall floor improvement.