Non-invasive characterization of chick embryo body and cardiac movements using near infrared light

Embryonic movements, body and cardiac activity, are important physiological phenomena for chick embryo development. Currently, there is no complete non-invasive method for simultaneously quantifying chick embryonic body motility and cardiac rhythm during incubation. This study investigates the use of a near infrared sensor to simultaneously monitor embryonic body and cardiac movements. Light brown chicken eggs (ROSS 308) were incubated for chick embryos activity signals measurement from day 6 to 19. Signal features (peak frequencies and signal energy) of chick embryo periodical activity were extracted to quantify both body and cardiac movements using fast Fourier transform and numerical integration. Two types of body movement were found throughout the whole incubation period. During the early stage of incubation, the movement was periodic; with the pattern differing between embryos. In the mid to late stages of incubation, movements were irregular and had a lower frequency compared to the periodic motion. Heart rates throughout the incubation period varied from 3.8 to 4.8 Hz, while heart beat strength sharply increased during incubation, peaking at day 13 to 14, and then subsequently subsiding. These results indicate that near infrared sensing, combined with signal processing, has the potential to monitor embryo motility and cardiac rhythm that could be used in developmental physiology, cardiovascular medicine and precision poultry production systems.