Impact of digital dermatitis on feedlot cattle behaviour

Digital dermatitis (DD) is an infectious disease affecting the bovine digital skin which can cause lameness and significantly affect animal welfare and economics. Digital dermatitis has emerged in feedlots and early identification of DD lesions is difficult using traditional visual methods. The objective of this study was to determine if changes in behaviour: rumination, feeding, inactivity and activity could be associated with DD in beef heifers and if these behaviours differed among DD M-stages (‘M′ for Mortellaro; 6-point classification describing the life cycle of DD). On arrival at the feedlot 120 heifers were fitted with accelerometers (CowManager system) attached to their Radio-frequency identification (RFID) tags to measure time spent ruminating, feeding, activity (walking and movement) and inactivity (lying and standing) throughout the feeding period. The study was conducted from November 2018 to November 2019 with heifer placements in fall 2018 and winter 2019. Biweekly pen walks were conducted to assess hind feet for presence or absence of DD using the M-stage scoring system and for altered gait using a lameness score. Detailed foot examination was conducted for heifers selected during pen walks, at routine re-handling events and prior to transport to the abattoir. In total 51 of 114 (44.74%) heifers were afflicted with DD. Among DD affected heifers 26 were classified as having active lesions and 25 as having chronic lesions. Behaviour pattern 5–2 days before detailed foot examination was analysed. Mean time spent ruminating ranged from 16% to 20%. Rumination time was significantly greater in heifers without DD lesions (P = 0.008) compared to DD affected heifers that ruminated 3% less per day. The effect of Day on mean daily rumination time depended on whether heifers had active DD lesions, chronic DD lesions or no lesion present (P = 0.034). Heifers with active DD lesions ruminated 5% less (P = 0.002) than heifers with no lesions. Mean time spent inactive ranged from 46% to 49% and was significantly greater in heifers with DD lesions (P = 0.035). The effect of Day on mean inactivity time depended on whether heifers presented with an active DD lesion, a chronic DD lesion or no lesion (P = 0.047). In conclusion, rumination is depressed, and inactivity increased in heifers with DD, 5–2 days before diagnosis. Taken together, our results describe the impact of DD on beef heifer behaviour and the potential utility of behaviour for early detection of DD.