WATER-LOSS FROM EGGS OF DOMESTIC-FOWL AND CALCIUM STATUS OF HATCHLINGS

Water balance in eggs of domestic fowl was manipulated by drilling hol es (each 3 mm in diameter) through the calcareous layer into the air c ell on day 10 of incubation. Water loss between days 0 and 18 averaged 6 g for eggs in the control group (no hole) but increased to 8, 12, a nd 15 g for eggs with 1, 2, or 3 holes, respectively. Hatching success was 79-87% for eggs with 0-2 holes through the eggshell but only 43% for eggs with three holes. Live mass of hatchlings declined as the num ber of holes drilled in the eggshell increased, but dry mass of carcas ses was unaffected by the treatments. The quantity of Ca2+, Mg2+, and phosphorus in residual yolks and yolk-free carcasses of hatchlings was not influenced by the amount of water lost from eggs. Plasma Ca2+ and Mg2+ were elevated in hatchlings from eggs with high rates of water l oss. The inability to regulate plasma Ca2+ may be a negative consequen ce of excessive water loss and could contribute to increased mortality of embryos.