Effects of Ganoderma spent substrate containing with polysaccharides and triterpenoids on the growth performance, antioxidant capacity and immunity level of chickens.

Ganoderma spent substrate (GSS) is the residual material of Ganoderma lucidum (GL) cultivation, which has abundant polysaccharides and triterpenoids. GL is widely recognized for its antioxidant and immune-boosting properties, however, the effects of GSS remain largely unexplored. This study aimed to investigate the effects of GSS on growth performance, antioxidant capacity, and immune function in chickens. Chickens were fed as follows: groups 1-2, basal diet; group 3, basal diet + GL spore powder (500 mg/kg); groups 4-6, basal diet + GSS (1.5 %, 3 %, or 4.5 %, respectively). Further, immunomodulatory targets were screened by combined kyoto encyclopedia of genes and genomes and gene ontology analyses, and identified using q-PCR and western blot. The results showed that GSS increased the production performance, antioxidant capacity, serum antibody titer, immunoglobulin and cytokine levels in chickens. B-cell lymphoma-2 (Bcl-2), epidermal growth factor receptor (EGFR), sarcoma (SRC), and signal transducer and activator of transcription 3 (STAT3) as the key regulatory genes, as well as p38 and extracellular regulated protein kinases as the critical proteins mediating immune function. The study demonstrated that GSS represents a promising feed additive, with optimal efficacy observed at a 3 % supplementation level.