Effect of arginine supplementation on liver and pectoral muscle: Tissue-specific lipid metabolism in broilers.

Abdominal fat (AF) and intramuscular fat (IMF) are key carcass traits in broilers but managing both is challenging due to their contrasting effects. Arginine (Arg) supplementation has potential effect in lipid metabolism, however its tissue specific effect remains poorly understood. The objective of this study was to investigate the tissue specific effect of Arg supplementation on growth performance and fat metabolism in both liver and pectoral muscle in broilers. A total of 480 Arbor Acre chicks were randomly assigned to four groups: Control (0 g/kg), Arg (1.8 g/kg), 5 × Arg (9 g/kg) and 10 × Arg (18 g/kg), with 12 replicates of 10 birds each. Overall, high Arg supplementation (5 ×, 10 ×) significantly impaired growth performance, reducing average daily gain and feed intake, accompanied by elevated serum AST and IFN-γ levels (P < 0.05). Liver transcriptomics analysis revealed that 10 × Arg significantly enriched PPAR signaling pathway, promoting fatty acid oxidation while suppressing lipogenic genes. Conversely, in pectoral muscle, high Arg (10 ×) promoted intramuscular fat deposition which was associated with downregulation of PPAR-α (P < 0.05) and increased expression of key lipogenic genes involved in de novo lipogenesis (SREBP-1c, FAS, ACC and SCD). Moreover, Arg supplementation modulated drug metabolism genes in liver, including EPX and RRM2, suggesting potential impacts on detoxification pathways. These findings underscore the importance of precise Arg dosing to optimize broiler growth, immune function, and carcass quality by targeting its tissue specific metabolic effect.