KMAN Publication Inc. Journal of Poultry Sciences and Avian Diseases 2981-135X 4 Serial Number 15 2026 06 20 Dietary Digestible Methionine+Cystine Levels Influence Performance, Egg Quality, and Hepatic Gene Expression in Post-Molt Laying Hens Dietary Digestible Methionine+Cystine Levels Influence Performance, Egg Quality, and Hepatic Gene Expression in Post-Molt Laying Hens 1 18 10.61838/kman.jpsad.186 EN Journal Article <table> <tbody> <tr> <td> This study evaluated the effects of graded digestible methionine+cystine (dMet+Cys) levels (0.490–0.698%; dMet+Cys: lysine ratios of 75–107) on performance, egg quality, plasma metabolites, and hepatic gene expression in post-molt Hy-Line W-80 laying hens (79–95 weeks). One hundred eighty hens were assigned to five isonitrogenous (15.06% CP) and isoenergetic (~2,800 kcal/kg AME) treatments in a completely randomized design with six replicates of six hens each. Increasing dMet+Cys linearly improved hen-day laying rate (79.92% to 87.12%; p<0.001), egg mass (52.18 to 58.22 g/hen/day; p<0.001), and feed conversion efficiency (p≤0.002). Egg weight showed a quadratic response, peaking at 0.648% dMet+Cys (68.90 g; p=0.003). Haugh unit and albumen index increased (p≤0.021), while egg component proportions remained unchanged (p>0.10). Plasma methionine, cysteine, homocysteine, and glutathione rose linearly (p≤0.003), indicating enhanced SAA flux and antioxidant capacity. Hepatic qPCR revealed marked downregulation of sulfur amino acid metabolism genes (MTR, CBS, CTH, BHMT, MAT1A, GPX1) and egg quality-related genes (OVAL, LYZ, TF, CA2, OC-17, KRT75) at higher dMet+Cys levels relative to the deficient basal diet (p<0.0001), suggesting homeostatic feedback and systemic metabolic reprogramming under adequate SAA supply. These results indicate that 0.648% dMet+Cys (dMet+Cys: lysine ≈ 99) optimizes post-molt performance and egg quality in white-egg layers through balanced metabolic and nutrigenomic regulation. </td> </tr> </tbody> </table>

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