This study used a non-invasive method of ballistocardiography to investigate cardiac work of chick embryos. In this method, an eggshell with electric charges on it is one capacitor plate, the other being a receiving antenna of the measuring equipment. Chick embryo cardiac work induces micro-movements of the whole egg, resulting in changes in the distances between the plates and thus in the difference of potentials between the shell and the receiving antenna. This is registered by the measuring equipment. The first single signals of cardiac work were registered on day 7 of incubation. Starting from day 9, the signal was recorded from all embryos. During the study, the heart rate decreased from 248 to 161 beats per minute and signal amplitude was found to steadily increase from 6.3 to 432.7 mV/m. Great disturbances in ballistocardiograms were observed on days preceding embryonic deaths.

Due to the ease of absorption, accumulation in tissues, and extremely long biological half-life in the body, cadmium is considered one of the most hazardous heavy metals. The aim of the study was to investigate the effect of in ovo injection of cadmium on chicken embryo heart. A total of 160 chicken hatching eggs were used in the study. On day 4 of incubation, eggs from the experimental groups were injected with cadmium at a dose of 1 and 5 µg/egg and the incubation was prolonged to 21 day until hatching. Cadmium was found to slow the heart rate and reduce heart weight. In embryos exposed to 5 µg of cadmium, the histological analysis and aminotransferases concentration confirmed the occurrence of inflammatory processes in the heart muscle.