Comparisons between invasive and noninvasive determinations of embryonic heart rate in chickens.

The embryonic heart rate (HR) of chicken eggs was determined by ballistocardiography, electrocardiography, impedance-cardiography and acoustocardiography. The effects of these different methods on the HR were examined for young (12-day-old) and late (16- and 18-day-old) embryos. Ballistocardiography is a non-invasive method. Nevertheless, the mean HRs determined using this method at 5-hr intervals were significantly different in many embryos. This difference was caused by the natural variability of embryonic HR. The statistical analyses indicated that any of these four methods did not influence the HR measurement and can be used as a simple means for determination of the embryonic HR.