Preferences of dairy cows for different types of grooming brushes

Dairy cows are highly motivated to use grooming brushes, and their use promotes expression of natural behavior. Although brushes are increasingly common on commercial dairy farms, little is known about how their mechanical properties, specifically swingability and rotation, influence cattle preferences for brush use. This study investigated adult dairy cow preferences for 3 brushes identical in physical and visual features but differing mechanically: (1) swinging and rotating, (2) swinging-only, and (3) stationary (neither swinging nor rotating). We predicted cows would prefer swinging brushes for their ability to reach multiple body regions and that rotation would further enhance engagement. Fourteen primiparous Holstein cows were habituated and individually exposed to all 3 brushes before testing. Over 9 d, each cow had simultaneous access to all brushes during 5-min sessions in a test arena. Brush interactions were video recorded and analyzed for first-choice preference, grooming duration, and body region contacted (head, neck, back, or rump); generalized linear mixed models accounted for zero inflation and repeated measures (back-transformed values with 95% CI). There was individual variation in brush preference; 10 of the 14 cows preferred the swinging-rotating brush, 3 preferred the swinging-only brush, and one preferred the stationary brush, based on total brush use duration. First-choice rates did not differ between swinging-rotating and swinging-only brushes, but both were greater than first-choice rates for the stationary brush or no brush choice. Grooming time varied by brush type and body part. Cows used all brushes to groom the head for similar durations (approximately 113, 103, and 122 s for swinging-rotating, swinging-only, and stationary brushes, respectively), but the stationary brush was used almost exclusively for the head. Cows used the swinging-rotating and swinging-only brushes for similar durations to groom other body parts. To groom the neck, cows used the swinging-rotating brush more than the stationary brush (approximately 95 and 13 s, respectively), but not more than the swinging-only brush (approximately 59 s). To groom the back and rump areas, cows used the swinging-rotating brush (approximately 92 and 144 s, respectively) and swinging-only brush (approximately 31 and 81 s, respectively) more than the stationary brush (approximately 1 and 9 s, respectively). Overall, cows favored brushes that could swing, likely because this feature enabled grooming of multiple body regions. However, the stationary brush may offer more tactile precision for head grooming. Brush design, particularly swingability, strongly influences cow grooming behavior. Future research should explore how providing brush variety affects welfare and investigate the underlying motivations for individual preferences.