Associations of behavior-based measurements and clinical disease in preweaned, group-housed dairy calves.

Producers report bovine respiratory disease and neonatal calf diarrhea as the 2 most common diseases in preweaned calves, both of which can affect calf performance and welfare. Housing calves in groups during the preweaning period has increased in popularity and has the potential to improve calf welfare, but only if producers can detect and treat disease efficiently. A health-screening tool is needed that allows producers to identify suspect animals but minimize the time spent examining healthy animals. The objective of this study was to determine if disease in preweaned, group-housed dairy calves was associated with behavioral measures of illness. This cross-sectional study included the evaluation of preweaned, group-housed calves (n=206) on 4 farms in Wisconsin, United States. Farm visits included the scoring of key behaviors (abnormal posture when lying or standing, isolation from the group, lethargy, and 2 approach tests that tested the willingness of calves to approach a stationary person) that were hypothesized to be components of sickness behavior. Following the behavior scoring, calves underwent an individual health assessment for bovine respiratory disease, neonatal calf diarrhea, and umbilical infections. Each behavior category was scored as normal (0 points) or abnormal (1 point), and then categories were summed to obtain a total behavior score for each calf. Behavior scores ranged from 0 (normal) to 5 (severely abnormal). A total behavior score of 3 or greater was considered positive for disease. The outcome of a positive or negative test on the behavior score were analyzed using PROC LOGISTIC (SAS Institute Inc., Cary, NC) and the model controlled for calf age and farm. Bovine respiratory disease was significantly associated with a behavior score of 3 or greater. The use of a behavior score shows promise as a screening tool for disease in preweaned calves.