Heart rate variability: a biomarker of dairy calf welfare

Abstract

Dairy calf welfare is recognised to be compromised from common management practices. In this study heart rate variability (HRV) was used to measure stress in 25 young dairy calves to quantify the degraded welfare they experienced from weaning separation and isolation and also the painful disbudding procedure. It was shown the time spent on the cow before separation had a significant negative correlation to HRV (r2 = –0.68, P = 0.03). The longer a calf spent in isolation the lower its HRV 3 days after joining a group pen (P = 0.037). The removal of a dummy teat elicited a significant drop in HRV (P = 0.05), identifying the addictive properties of sucking in calves. Post disbudding stress, reflected by declining HRV values, was only partly alleviated by the non-steroidal anti-inflammatory drug meloxicam after 48 h. The findings showed calf welfare would be improved by reducing the time between birth and separation and also the days spent in single pens. Providing dummy teats for individually housed calves showed potential as a positive environmental enrichment. Meloxicam may improve welfare by alleviating some chronic pain following hot iron disbudding. We conclude these findings illustrate that HRV, as a science-based animal-centric biomarker of animal welfare, may be used to help improve farmed animal practice.