The mRNA expression levels of C/EBP-β and asparagine synthetase (Asns) revealed that dietary treatment significantly downregulated the mRNA expression levels of C/EBP-β and Asns, which is consistent with decreased serum free Arg, His, Met, Thr, Ala, Asp, Glu, Gly, Leu, and Ser, indicating NAFLD induced by excessive dietary valine dramatically impaired liver amino acid metabolism of laying hens (Figures 1D,E). Here, ASNS is linked to metabolic dysfunction-associated steatotic liver disease.