Effects of Lactobacillus plantarum and Florfenicol on Growth, Immune Response, and Nutrition Metabolism in Sebastes schlegelii

Abstract

This study evaluated the effects of Lactobacillus plantarum LP37 and florfenicol (FF) on growth performance, immune response, and nutritional metabolism in Sebastes schlegelii. Four experimental groups of fish were established: a control group (CK, basal diet), LP37 group (basal diet + 10⁹ CFU/g LP37), FF group (basal diet + 20 mg/kg FF), and FF-LP37 group (FF-supplemented diet for 15 days, followed by LP37-supplemented diet for 15 days). Serum, liver, and kidney samples were collected for biochemical and molecular analyses. The FF-LP37 group exhibited the highest weight gain and specific growth rates (SGRs) than those in the CK group (p < 0.05). Antioxidant indices showed that superoxide dismutase (SOD) activity was evaluated in LP37 and FF-LP37 groups; catalase (CAT) activity increased in FF group serum and FF-LP37 group liver (p < 0.05); total antioxidant capacity (T-AOC) was higher in all supplemented groups than in CK (p < 0.05); malondialdehyde (MDA) levels were elevated in the FF group (p < 0.05). Nutritional metabolism-related enzymes (hexokinase [HK], pyruvate kinase [PK], phosphoenolpyruvate carboxykinase [PEPCK], glutamine synthetase (GS), glucokinase, phosphoglucomutase, lipoprotein lipase [LPS], and fatty acid synthase [FAS]) were significantly altered, particularly in LP37 and FF-LP37 groups (p < 0.05). Molecular analysis revealed that expression of interleukin-1 receptor-associated kinase 4 (IRAK-4) and myeloid differentiation primary response 88 (MYD88) in the liver and kidney was upregulated in the FF group (p < 0.05), but downregulated in the LP37 and FF-LP37 groups compared with CK. In conclusion, dietary supplementation with LP37, FF, or the FF-LP37 sequence improved S. schlegelii growth, AOC, immunity, and nutritional metabolism, providing valuable insights for aquaculture dietary strategies.