PREDICTING TOMORROW: OPTIMIZING THE EARLY DETECTION OF DISEASE AND DISEASE RECOVERY IN DAIRY CALVES USING PRECISION TECHNOLOGIES

The leading causes of morbidity and mortality in preweaned dairy calves are diarrhea and bovine respiratory disease complex (BRD). The delayed detection of these diseases in calves can also delay intervention and disease recovery. The overarching objective of this dissertation was to follow a cohort of calves daily for the first 90 days of life for naturally occurring clinical BRD bouts and diarrheal bouts. The objective answered if feeding behaviors and activity levels were different in at-risk calves during BRD development and BRD recovery from an antimicrobial intervention. Furthermore, the potential of colostrum replacer as a feeding intervention strategy to ameliorate disease bouts and improve performance in calves was explored. Thus, the objective of the first study was to investigate the relationship between feeding behavioral patterns and activity levels in preweaned calves for the five days before clinical BRD diagnosis using precision technologies to document these behaviors. Next, we investigated if dairy calves presented different behavioral responses after antimicrobial intervention for BRD depending on the outcome of the treatment (recovered or relapsed). Finally, we assessed if providing an early intervention of colostrum replacer to at-risk calves (e.g., at-risk by algorithm classification) could ameliorate disease bouts (e.g., diarrhea and BRD). A cohort of socially housed, Holstein calves born on one research facility (n=120) were health-scored daily from birth to 90 days of age (e.g., 14 days after weaning). Calves were fed by automated feeders which recorded daily milk and calf starter intakes, drinking speed, rewarded and unrewarded visits. All calves wore a commercial pedometer (IceQube, IceRobotics, Scotland) on their left rear leg. The pedometer recorded daily activity levels (lying time, lying bouts, step count, and an index based on rate of acceleration and step count). Prior to clinical BRD, destined-to-be-sick calves had negative relative changes in their calf starter intakes, and treatment day interacted with BRD status for relative changes in unrewarded visits to the feeder, step count, and the activity index. For BRD calves at-risk for relapse, there were lower starter intakes and lower unrewarded visits compared to recovered calves. Furthermore, within the 10-days after antimicrobial intervention, relapsed calves had lower activity levels compared to recovered calves. Colostrum intervention ameliorated the likelihoods of a BRD bout, but not diarrhea, without affecting performance in dairy calves. These results suggest that in calves, negative relative changes in starter intake, and decreased step counts may be powerful indicators of BRD and recovery status. Colostrum intervention may also ameliorate BRD bouts in calves