Effects of pre-incubation egg storage on embryonic functions and growth

The effect of pre-incubation storage on physiological functions of chick embryos during the last half of incubation and the relationship to embryonic growth were studied. In the first experiment, eggs were stored for 20 or 30 days, respectively, and the developmental patterns of oxygen consumption (MO2), heart rate (fH) and O2 pulse of individual embryos were examined. The MO2 of stored eggs increased at significantly lower rate than the control between day 12 and 17 of incubation, and the stored eggs had a significantly lower plateau MO2 between day 17 and 19. The decrease in MO2 of some stored eggs was correlated with late incubation mortality. Pre-incubation storage also resulted in significant changes in the developmental patterns of fH and O2 pulse. In the second experiment, the eggs were stored for 10 and 20 days, respectively, to also examine the effect of short-term storage on the development of MO2 in relation to embryo growth. Pre-incubation storage for 10 days had no significant effect, but 20 days storage shifted developmental patterns of MO2, wet mass, dry mass and embryo water fraction to the right of the control. Furthermore, MO2 was significantly lower than expected on the basis of embryo mass after day 17 of incubation. Prolonged pre-incubation storage caused not only a rightward shift in MO2 pattern due to retarded growth, but also severe depression of MO2 during the last stages of prenatal development.