Yeast β-glucan selenium nanoparticles enhance meat quality in heat-stressed broilers via SelO-mediated mitochondrial...

Heat stress (HS) markedly impairs broiler growth, muscle function, and meat quality. In this study, broilers were subjected to a 2 × 2 factorial design with sodium selenite or yeast β-glucan selenium nanoparticles (yeast β-Glu-SeNPs) as the selenium source (0.3 mg/kg total selenium) under thermoneutral or HS conditions. We aimed to investigate the protective effects and underlying mechanisms of yeast β-Glu-SeNPs against HS-induced muscle damage.

HS markedly impaired growth performance and induced systemic oxidative stress and inflammation, while also compromising meat quality and disrupting postmortem glycolysis, as evidenced by reduced glycogen availability and excessive lactate accumulation. Yeast β-Glu-SeNPs significantly improved growth performance, mitigated oxidative stress and inflammation, and restored meat quality in both breast and thigh muscles. Postmortem energy metabolism was preserved, as reflected by increased muscle glycogen and glycolytic potential, reduced lactate accumulation and glycolytic enzyme activities, and a stabilized pH decline. Meanwhile, skeletal muscle Se deposition, glutathione peroxidase activity, and key selenoprotein expression were markedly enhanced. Notably, HS promoted a phenotypic shift toward fast glycolytic muscle fibers, as evidenced by increased expression of MYHC2b and Fast-MyHC (P < 0.05), accompanied by reduced levels of MYHC1, MYHC2a, and Slow-MyHC (P < 0.05). This maladaptive transition was effectively reversed by yeast β-Glu-SeNPs, which favored oxidative fiber formation, characterized by the upregulation of MYHC1 and MYHC2a, along with the suppression of MYHC2b (P < 0.05). At the mitochondrial level, yeast β-Glu-SeNPs preserved ultrastructural integrity and enhanced mitochondrial function, as reflected by increased ATP content, elevated mtDNA copy number, and the upregulation of mitochondrial biogenesis-related genes, including AMPK, PGC-1α, NRF1, and TFAM (P < 0.05). Correlation analysis, molecular docking, and co-immunoprecipitation demonstrated that SelO interacts with AMPK, supporting a SelO-dependent AMPK/PGC-1α axis that drives mitochondrial biogenesis and oxidative fiber remodeling.

Overall, yeast β-Glu-SeNPs mitigated HS-induced muscle metabolic dysfunction and meat quality deterioration via SelO-mediated mitochondrial and myofiber reprogramming.