highly significantp < 0.001
Eight energy metabolism pathways (oxidative phosphorylation, citrate cycle, glycolysis/gluconeogenesis, pyruvate metabolism, pentose phosphate pathway, butanoate or propanoate metabolism, synthesis and degradation of ketone bodies, and fatty acid metabolism) and four amino acid metabolism pathways (arginine and proline, phenylalanine, tryptophan, and the aliphatic amino acids valine, leucine and isoleucine metabolisms) were identified, most of them at the three stages and highly significant ( p < 0.001; Table 2 ).