Additionally, long-term exposure to high levels of dietary valine at 0.74 and 0.79% has accelerated the development of NAFLD of laying hens by promoting lipogenesis and inhibiting fatty acid oxidation mediated by GCN2-eIF2α-activating transcription factor 4 (ATF4) (32, 33). The gene discussed is EIF2AK4; the disease is metabolic dysfunction-associated steatotic liver disease.