2026 Conference of Research Workers in Animal Diseases46 CRWAD 2026 ABSTRACTS 12 - Integration of sensor data and lesion history for predictive modeling of dairy cow lameness. T. Rahman*, E. Shepley, and G. Cramer, University of Minnesota, Twin Cities, MN Timely identification of individual lameness is critical for dairy herd health and productivity. While traditional methods rely on subjective visual scoring, the adoption of precision dairy technologies provides an opportunity for objective, continuous monitoring. The study’s objective is to develop and validate a predictive model for locomotion score using behavioral data collected from neck-mounted sensors and historical foot lesion occurrence. Sensor data were collected from 2 commercial dairy farms in Minnesota between January and July 2025. The dataset included daily totals for eating time, rumination time, and inactive time, measured by collar sensors, alongside corresponding visual locomotion scores (0–3) provided by experts (score 0 is a non-lame and score 3 is a severely lame cow). After data cleaning, a total of 6,561 cow-days from 846 unique cows were available for analysis. The locomotion scores were categorized as lame (score 0 and 1; n = 176) and non-lame (score 2 and 3; n = 670) cows. To account for repeated measures on individual cows, the dataset was split into training and testing sets by individual cow, ensuring no over- lap between sets. A random forest model was developed using average eating, rumination, and inactive time from the 2 weeks before the locomotion score date, their standard deviations, days in milk, lactation number, and lesion history as predictors. Model performance was evaluated across 30 randomized iterations. While the predictive model achieved high average accuracy (76%), its performance was driven by high specificity (84%) at the expense of low sensitivity (46%), indicating the model was proficient at identifying non-lame cows but struggled to detect lame cows. Lower sensitivity might be caused by unbalanced classes in the dataset. The initial results indicate that behavioral measures can explain a substantial portion of the variation in locomotion scores. Key Words: lameness, dairy cattle, wearable sensor, machine learning, animal behavior, precision dairy