Research Note: Measuring the electrocardiogram of male and female chicken embryos using wireless telemetry

Chicken embryo heart rate (HR), temperature, and ECG were recorded to determine sex differences during incubation. HR and QRS amplitude (QRSa) were hypothesized to be different between males and females. Ten replicates of 30 White Leghorn eggs each were used. These eggs had 96.62 % fertility. Eight eggs per replicate were randomly selected for ECG telemetry. Each transmitter device had two insulated wires placed in 1 mm holes in the shell without piercing the shell membranes. Continuous HR and local egg temperature data were recorded 15 minutes per day from days 8-17 in replicates 1-6 and days 6-17 in replicates 7-10. 10-minute segments were analyzed. The ECG software marked waveforms automatically and logged HR and QRSa averages every 5 seconds. Transmitters were removed on day 18 of incubation. Average hatchability was 78.29 % for transmitter eggs and 78.87 % for non-transmitter eggs. Day-old chicks were humanely euthanized, weighed, and sexed. Multitrait analysis of the ECG data was not possible with this dataset, including temperature interactions. Therefore, HR and QRSa were analyzed separately. Predictive models represented days 6-17 and 6-10. The simple effects of sex were not significant (p ≥ 0.10). Days 6-10 resulted in a significant sex by quadratic day interaction for HR (p = 0.0063) and a sex by cubic day interaction for QRSa (p = 0.0741). Overall HR ranged from 240 to 290 bpm. Females had numerically higher HR than males from days 7-9, though not significantly different. These data provide a starting point for further improvements in electrocardiogram technology used for different poultry life stages.