Polysaccharide from Walnut Green Husk alleviates ochratoxin a-induced anorexia in chicks via m6A-mediated FXR regulation of orexigenic genes

Ochratoxin A (OTA) is a common mycotoxin in poultry feed that impairs feed intake and growth performance, leading to substantial economic losses. Walnut green husk polysaccharides (WGP) have previously been reported to alleviate OTA-induced hepatic and intestinal damage, but their effects on anorexia and underlying mechanisms remain unclear. This study investigated whether WGP mitigates OTA-induced anorexia in broilers and explored its molecular basis. One-day-old broilers were fed OTA diets with or without WGP supplementation for three weeks. WGP significantly improved feed intake and body weight, attenuated hypothalamic inflammation, and restored the mRNA expression of orexigenic neuropeptides (AGRP, NPY). 16S rRNA sequencing and serum metabolomics revealed that WGP reshaped gut microbial composition and bile acid (BA) profiles, increasing the abundance of Lactobacillus and Bifidobacterium and restoring CA and DCA levels. WGP also reversed OTA-induced reductions in FXR protein expression despite unchanged FXR mRNA levels, suggesting post-transcriptional regulation. Consistently, OTA increased global m⁶A methylation and upregulated METTL3 and YTHDF2 expression, which were significantly attenuated by WGP. SELECT-qPCR further confirmed that m⁶A enrichment at a specific site in FXR mRNA was elevated by OTA but reversed by WGP. These findings indicate that WGP alleviates OTA-induced anorexia via the gut microbiota-BA-FXR-m⁶A-neuropeptide axis, revealing a novel epigenetic mechanism in appetite regulation and highlighting WGP as a promising dietary strategy to mitigate mycotoxin-induced anorexia in poultry production.