Use of Electrocardiogram to Evaluate Welfare of Laying Hens and Chicks During Different Life Stages and Events

Three separate studies were conducted to evaluate the welfare of laying hens and chicks during different life stages. The stress responses of mature laying hens in two different scenarios were also investigated. All three studies utilized the electrocardiogram (ECG) as the chosen tool for data collection. Study 1 examined the startle response, prompted by an acute stressor that created sudden movement and noise, in White and Brown Leghorn hens housed in either cages or aviaries. The presence of a chronic stressor, a 23-hour feed failure, was also assessed as a factor. These hens had been surgically implanted with wireless ECG telemetry devices and heart rate (HR) was calculated. Production data were not affected by stressors, but caged hens with feed removed had higher HR 2 minutes after the startle. The second study examined differences in HR and QRS amplitude (QRSa) in White Leghorn hens during different methods of on-farm euthanasia. Hens euthanized via cervical dislocation retained high HR longer than hens euthanized via CO2 displacement. This could indicate that cervical dislocation is a more stressful method of euthanasia for the hen, but the findings of this study continued to support the use of either method by trained personnel. The third study examined HR, QRS amplitude, and proximal temperature of chicken embryos from days 6-17 of incubation to determine if significant differences exist based on sex. Wireless ECG telemetry were attached to fertile White Leghorn eggs without piercing the shell membrane in order to collect data noninvasively. Significant sex by day interactions were present during days 6-10 for HR and QRSa datasets. Models were developed for predicting HR and QRSa in males and females. There is great potential for further study. Immature male and female white Leghorns also had HR calculated from ECG recordings. Females had higher HR and numerically lower QRSa which was supported by previous literature. Advisor: Sheila E. Purdum