Integrated Analysis of Carotenoid Metabolism, Lipid Profiles, and Gut Microbiota Reveals Associations Fundamental to Skin Pigmentation in Lingshan Chickens

Skin color is a crucial phenotypic trait in poultry that influences consumer preference, market value, and breed identification. However, the mechanisms underlying skin color variation in Lingshan chickens remain poorly understood. This study aimed to elucidate the physiological, metabolic, and microbial characteristics associated with skin color differences in male Lingshan chickens. A total of 210 castrated male Lingshan chickens were categorized into white-shanked (WS), yellow-shanked (YS), and red-shanked (RS) groups based on the Roche color fan scores. The results showed that chickens in the YS and RS groups exhibited significantly higher body weights and pigmentation levels in the shank, breast, and abdominal skin compared to those in the WS group (<i>p</i> < 0.05). Serum concentrations of triglycerides (TG), total cholesterol (TC), high-density lipoprotein (HDL), low-density lipoprotein (LDL), and very-low-density lipoprotein (VLDL) were markedly elevated in RS chickens. Additionally, carotenoid profiles revealed higher deposition of lutein and β-carotene in the skin and adipose tissues of YS and RS birds. Gene expression analysis indicated differential regulation of carotenoid transport and metabolism-related genes among groups. Furthermore, 16S rRNA sequencing of cecal microbiota revealed significant compositional shifts in microbial communities associated with shank pigmentation. Collectively, these findings suggest that differences in shank color in Lingshan chickens are closely linked to lipid metabolism, carotenoid transport, and gut microbiota composition. This study provides novel insights into the biological mechanisms driving skin pigmentation, offering valuable implications for breeding and functional trait selection in indigenous chicken populations.