Upregulation of the TCA cycle leads to an increase in energy generation from the oxidation of acetate, derived from carbohydrates, fat and proteins. As synthesis and degradation of glycogen are vital for embryonic survival during the last phase of incubation, glycogen levels were determined in liver, the most metabolically active tissue of the embryo. Although no significant effects of treatment or an interaction with age could be observed, the albumen-deprived chicks had lower hepatic glycogen content at hatch as compared to both the control and the sham group, suggesting that the released glucose can be distributed to extrahepatic tissue or be used as an energy source in the liver. The variation in glycogen content between individual chicks, however, was very high, but since chicks were randomly selected for sampling, individual chicks may exhibit different hatch times and it is known that time of hatching has an impact on hepatic glycogen content. Reduced liver glycogen content at hatch can be caused by either an increased use of glycogen during the hatching process or a decreased build-up of glycogen before hatch, although the latter is not likely since no differences in glycogen content were detected at ED20. It seems that the albumendeprived chicks had to degrade more of the hepatic glycogen content, needed as energy source during the energy demanding hatching process. Interestingly, several of the affected proteins are involved in glucocorticoid receptor signaling. Glucocorticoid hormones have a central role in the regulation of the glucose metabolism and bind to the GR, which is a transcription factor for regulating gene expression. In sheep, glucocorticoid receptor expression is increased in the liver of neonatal offspring born to ewes which were nutrient restricted during early-mid-gestation. Offspring of rat dams that were protein-restricted throughout gestation had increased glucocorticoid receptor protein and mRNA expression in liver during fetal and postnatal life. The GR was not identified amongst the upregulated proteins, yet may not appear in a 2-D DIGE gel due to its membrane location. However, several proteins involved in GR signaling were upregulated. The level of plasma corticosterone, an important glucocorticoid in birds, however, was not affected in our model. An upregulation of ENO1 and GLUT1 can be associated with increased TR/RXR activation. The thyroid hormone receptor is usually found as a heterodimer with RXR and regulates gene expression. Thyroid hormones are involved in a range of biological processes such as growth, development and metabolism. Plasma thyroid hormone concentrations, both T3 and T4, are reference measurements for evaluating the level of metabolism of the embryos. Plasma T3 concentrations, the biologically active form of thyroid hormone, however, did not differ between groups indicating a decreased metabolism.