Deciphering the impact of stickwater hydrolysate on growth performance, immune response, and IGF-1/PI3K/AKT/mTOR signaling pathway in Siberian sturgeon (Acipenser baerii) fingerlings.

Abstract

A feeding trial lasting 56 days was carried out to assess how the inclusion of stickwater hydrolysate (SWH) in the diet of Siberian sturgeon (Acipenser baerii) fingerlings affected their growth performance, immunity, digestive enzyme activity, and gene expression linked to the IGF-1/PI3K/AKT/mTOR signaling pathway. Siberian sturgeon fingerlings were acclimatized and fed isonitrogenous, isoenergetic diets with varying SWH concentrations (0%, 0.5%, 1.5%, and 2.5%). Growth parameters, serum proteins, immunological and digestive enzyme activities, and gene expression levels were assessed post-trial. Results demonstrated that 0.5%, and 1.5% SWH treatments significantly improved weight gain, specific growth rate, feed conversion ratio, and protein efficiency ratio. Notably, these diets also elevated serum protein and plasma globulin levels, reduced albumin-to-globulin ratios, and enhanced lysozyme, myeloperoxidase (MPO) activities, and immunoglobulin (Ig) M levels, indicating an immunostimulatory effect. Digestive enzyme activities were markedly increased in the SWH groups, particularly at 1.5%. Gene expression analyses revealed upregulation of mtorc1, s6K, akt, pi3k, and igf1, with concurrent downregulation of 4e-bp1 in the muscle of fish, signifying activation of the IGF-1/PI3K/AKT/mTOR pathway, which is central to protein synthesis and muscle growth. In conclusion, SWH at appropriate levels significantly enhances growth, digestive efficiency, and immune function in Siberian sturgeon fingerlings, while also activating key metabolic pathways.