Heart Rate Response of Chicken Embryos to Room Temperature at Different Ages

Chicken ( Gallus gallus domesticus ) embryos are used as a research model. Embryotic heart rate (HR) can be monitored non‐invasively for health as well as a physiological response to experimental stimuli. References ranges for embryotic HR vary with cardiovascular and embryonic development. These may be influenced by the environment in which they are measured. A decline in heart rate (HR) has been documented in embryos following removal from incubation. This was hypothesized to be a response to the drop in ambient temperature. The magnitude and duration of this response may vary with embryonic development. To evaluate the effect of ambient temperature on chicken embryo HR, 10‐day, 15‐day, and 18‐day old chicken embryos (n = 20, 15 and 15 respectively) were placed on HR monitors for 10 min at both incubation (37.7 ± 0.1 °C) and room (25.6 ± 0.4 °C) temperatures. The pattern of HR change was similar in both temperature groups. HR predictably increased with embryonic age (p < 0.05); HR across all ages decreased similarly (p > 0.10). After a decrease in HR after 3 min (−30 ± 39 bpm, p < 0.01), HR did not continue to decline (p > 0.05). Differences in both HR between embryotic stages and changes in HR over the 10 minute trials were temperature independent (p > 0.05; p > 0.10). This would suggest that chicken embryo research can be conducted at room temperature within 10 min (in 10 – 18‐day embryos) without temperature significantly impacting HR. Initial decreases in HR may not be due to temperature, but rather other factors associated with movement and manipulation. When looking at changes in HR, egg handling procedures and embryo age should be considered and controlled. Support or Funding Information Research reported in this publication was supported by the MENTORES (Mentoring, Educating, Networking, and Thematic Opportunities for Research in Engineering and Science) project, funded by a Title V grant, Promoting Post‐baccalaureate Opportunities for Hispanic Americans (PPOHA) | U.S. Department of Education, Washington, D.C. PR/Award Number: P031M140025. The content is solely the responsibility of the authors and does not necessarily represent the official views of the Department of Education.