Effects of Lameness on Milk Yield, Milk Quality Indicators, and Rumination Behaviour in Dairy Cows Before, During, and After 7 Days of Diagnosis

Objectives: Lameness in dairy cows is a well­ documented issue in scientific literature, with significant implications for both animal welfare and farm economics. However, less attention has been given to its temporal progression—before, during, and after diagnosis. There is a notable gap in research exploring how productivity and health metrics evolve across these stages of lameness. This perspective is critical for understanding both the onset and recovery phases of lameness, which can inform better management and treatment strategies for aYected cows. This study aimed to leverage data from existing sensors to identify clinical lameness through behavioural patterns and milk performance metrics. Specifically, the aim of this study was to evaluate the eYects of lameness on milk yield, milk quality indicators, and rumination over three key time points: 7 days before diagnosis, on the day of diagnosis, and 7 days after diagnosis. Methods: The study monitored 24 multiparous Holstein dairy cows during early lactation (up to 100 days postpartum) using a 1-to-5 scoring system to assess lameness. Lameness was found to significantly aYect rumination and milk production. Daily data were collected using Lely Astronaut® A3 milking robots, recording parameters such as rumination time (minutes/ day), body weight (kg), milk yield (kg/day), milk protein content ( %), milk fat content ( %), milk lactose concentration ( %), and somatic cell count (SCC, thousand/mL). These metrics were analysed for 7 days pre­ diagnosis, on the day of diagnosis, and 7 days post­ diagnosis. Results: On the day of diagnosis, rumination time dropped by 26.64 % compared to the pre­ diagnosis period (p < 0.01) and by 26.06 % relative to healthy cows, highlighting its potential as an early health indicator. Milk yield decreased by 28.10 % compared to pre- -diagnosis levels (p < 0.01) and by 40.46 % compared to healthy cows (p < 0.05). These results suggest that lameness aYects productivity and welfare even before clinical signs become apparent. Milk composition also changed significantly, with lame cows showing increased fat (+0.68 %, p < 0.05) and reduced lactose (-2.15 %, p < 0.05) content compared to healthy cows. Positive correlations were observed between rumination time and milk yield (r=0.491, p < 0.001), while negative correlations were identified between milk yield and milk fat, protein, and the fat- to­ protein ratio (p < 0.001). Conclusions: This study underscores the value of sensor­ based monitoring for early and accurate detection of lameness in dairy cows. Significant reductions in rumination time and milk yield were observed on the day of diagnosis, along with a decrease in milk lactose concentration. These findings suggest that changes in rumination, milk yield, and lactose content could serve as early warning indicators of lameness. Incorporating real­ time milk quality monitoring with gait analysis could support more informed management decisions, improving animal welfare and minimizing economic losses.