324. Behavioral Responses of Impaired Feedlot Cattle After Chronic Pen Entry and Associations with Time to Death.

Abstract In feedlots, chronically impaired cattle are often moved to specialized pens, where they have easier access to resources and to facilitate monitoring and care. Understanding how chronic cattle transition into this new environment may provide insights into their likelihood of recovery. The objectives of this study were to 1) describe the behavioral time budget of chronic cattle in the first 30 min after pen entry, and 2) determine associations between these behavioral variables and time to death. Continuous video of two chronic pens at a 50,000-head commercial feedyard in Alberta, Canada, was recorded on three cameras per pen. Behaviors of 36 focal cattle, individually identified with collars, were recorded for the first 30 min after entry to the chronic pen over a 1 year period (February 2024 to 2025). Behaviors assessed included posture (standing, lying) and active behaviors (feeding, drinking, walking, social interactions, grooming, and standing other or out of view (SO)). Final disposition, diagnosis (bovine respiratory disease (BRD), lame, and other), sex, and season were recorded for each animal and used for stratified random focal animal selection. Number of days from pen entry to final disposition were also recorded. Of the 36 focal cattle, 19 (53%) recovered and 17 (47%) died. Fourteen (39%) cattle had BRD (seven recovered, seven died), 15 (42%) were lame (six recovered, nine died) and seven (19%) had other diagnoses (six recovered, one died). For Objective 1, the behaviors most commonly observed were SO, standing at the feed bunk, lying idle, and walking (averaging 44%, 30%, 14%, and 10% of time, respectively). For Objective 2, data were analyzed using a Cox proportional hazards model with backwards elimination to assess behavioral and other predictors (diagnosis, season, sex) of time to death. The final model retained only a possible trend (p = 0.09), where a greater proportion of time walking during the first 30 min after pen entry was associated with a lower hazard of death. All other variables were non-significant (p > 0.10). Chronic cattle in this study spent most of their time in the first 30 min after pen entry either standing not engaged in any behaviors of interest (SO) or at the feed bunk. Greater walking time showed a trend toward a reduced hazard of death. Behavior observations at additional time points relative to pen entry, such as first feed delivery or the day after entry, should be investigated to determine if behavioral differences appear after cattle have spent more time in the chronic pen.