Blinking Patterns in Calves and Changes Following Restraint and Disbudding

Abstract The use of spontaneous eye blink rate [EBR] as a non-invasive stress measure is well documented in humans and is gleaning research attention in animal studies. Thus, this study investigated the EBR patterns and changes associated with two known stressful conditions, crush-restraint and disbudding, in dairy calves. Fifty-four female Holstein dairy calves were studied. EBR patterns were assessed in two separate studies (n = 10 in first study; n = 25 in replicate study) four times daily for 4-5 days. Additionally, the EBR of 19 calves divided into two groups (disbudded group = 13; sham group = 6) was recorded following crush-restraint and disbudding (under anaesthesia)/sham-disbudding (without anaesthesia). EBR was consistent across days and times in the first study but in the replicate study, it varied across days. The disbudded group had lower EBR following crush-restraint but was comparable with the sham group following disbudding. Findings suggest that spontaneous blinking may potentially serve as an instant measure of stress in dairy calves based on the elevations associated with crush-restraint and disbudding. However, blink rates may vary across days, and this should be considered when utilizing this measure to assess stress.