Oxidative stress and metabolic perturbations unravel the molecular basis of high dietary poultry by-product meal-induced growth impairment and inflammation response in Litopenaeusvannamei.

The pacific white shrimp, Litopenaeus vannamei (L. vannamei) is one of the most widely farmed shrimp species in global aquaculture. The scarcity of fishmeal as a component of aquafeeds poses a considerable challenge to the sustainable development of the aquaculture industry. This study aimed to assess the feasibility of poultry by-product meal (PBM) as an alternative to fishmeal of L. vannamei diets by assessing its impact on growth performance, immune response, postprandial metabolism and signaling pathways. Six diets were formulated to be iso-nitrogenous (42 %) and iso-lipidic (7 %), with 0, 8 %, 16 %, 25 %, 33 %, and 50 % fishmeal replaced by poultry by-product meal (marked as CON, PBM8, PBM16, PBM25, PBM33, PBM50). After an 8 weeks of growth trial, results showed that dietary PBM replacement up to 16 % didn't negatively affect growth performance of L. vannamei. However, PBM replacement at 16 % or higher led to significant reductions in lipase and trypsin activity, deteriorated gut morphology, and disrupted the balance of immune-related gene expression and phosphorylation of Nf-κB in the intestine or hepatopancreas. Mechanically, oxidative stress progressively increased in the hepatopancreas with higher dietary PBM levels, inducing ferroptosis and cuproptosis while leaving apoptosis and autophagy unaffected. Postprandial mTORC1 signaling in muscle was significantly suppressed by higher PBM levels, impairing protein synthesis. Furthermore, high PBM replacement disrupted postprandial energy metabolism, affecting glycolysis, gluconeogenesis, and TCA cycle pathways. Taken together, these results shed light on the molecular, immune and metabolic impacts of dietary PBM replacement in L. vannamei, enhancing comprehension of the relationship between dietary protein sources and shrimp physiological health.