THE EFFECT OF HIGHER GRAVITATION ON EMBRY ONIC-DEVELOPMENT OF BIRDS

An experiment was conducted on Japanese quail and hen hatching eggs th at had been incubated, and the embryos were subjected to hypergravitat ion of 10 G for 10 min on days 1 to 9 of embryonic development. Both t he experimental group and the control contained each 20 hatching eggs every day of the experiment (360 eggs in total). A centrifuge of the d iameter 1,300 mm was used to create overload (hypergravitation) at the speed of 118 rotations per min. Tab. I shows the layout of the experi ment. Embryonic mortality in Japanese quail was investigated during in cubation by egg candling on days 1 to 8 and 9 to 14 while suffocated e mbryos were investigated on days 15 to 17. As for chicks, embryonic mo rtality was determined by egg candling on days 1 to 8 and 9 to 18, suf focated embryos were determined on days 19 to 21. After incubation was terminated, hatchability in per cent of the fertilized eggs was deter mined. The results were processed in two stages of development: the fi rst stage days 1 to 5, the second stage days 6 to 9. As can be seen in Fig. 1, hypergravitation did not influence the hatchability of quail eggs in the first stage. But this experimental treatment resulted in a steep fall of hatchability in the second stage of observation in comp arison with the control group (the difference is significant P < 0.01) . Fig. 2 shows chick hatchability. It was considerably lower in the ex perimental group in the first stage of development if compared with th e control group, while in the second stage of development it was on th e level of control group. Embryonic mortality in Japanese quail, as ca n be seen in Fig. 3, was higher in the experimental group in the secon d stage on all days of observation. As for chicks, embryonic mortality was higher in the experimental group in the first stage of developmen t (Fig. 4). The results described seem to document various responses o f quail and hen embryos to hypergravitation in dependence upon their s tage of development. The determined differences in hatchability and mo rtality of quail and hen embryos could indicate specifically different responses to the used physical treatment.