Effects of different Lactobacillus pentosus feeding strategies on the growth, antioxidant capacity, and intestinal health of pearl gentian grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus) fed with oxidized fish oil diet

This research evaluated the impact of Lactobacillus pentosus (LP) various feeding strategies on growth performance, antioxidant capacity, and intestinal health of pearl gentian grouper (♀ Epinephelus fuscoguttatus × ♂ Epinephelus lanceolatus ) fed oxidized fish oil diets. The experimental design included five groups: fresh fish oil group (F), oxidized fish oil group (O), resistance group (LP was added to the O group diet for 60 d, R), prevention group (LP was added to the F group diet in the first 30 d and then switched to diet of O group, P), and treatment group (Contrary to P group, T). Juvenile groupers with initial body weights (21.42 ± 0.12 g) were fed for 60 days. The final results indicate that compared with O group, R, P, and T groups caused significant increases in FBW, WGR, and SGR of grouper, with P group demonstrating the best effect. The resistance group (R) showed the significantly greater performance with other group in maintaining serum HDL-C levels and reducing ALT and AST activities, indicating its effect in stabilizing liver function in the long term. Intestinal digestive enzyme activities were significantly enhanced in the R and P groups, and the P group continued to maintain higher levels after stopping feeding. Hepatic antioxidant indexes showed that MDA accumulation was significantly reduced, and antioxidant gene expression was enhanced in the R and P groups via the Nrf2-Keap1 signaling pathway activation. In addition, R group significantly up-regulated intestinal tight junction protein gene expression and improved intestinal barrier function. The conclusions indicated that all three feeding strategies were effective in alleviating growth inhibition and oxidative damage from oxidized fish oil, with the addition of LP throughout the entire breeding process (R group) performing optimally in maintaining antioxidant capacity, metabolic homeostasis, and intestinal health. These findings establish foundations for functional feed additive design, enabling prevention of oxidative damage from fish oil peroxidation in aquaculture systems. • Adopt multiple LP feeding strategies to address the harm caused by grouper feeding on OFO. • Various application strategies for LP alleviated the growth inhibition of grouper caused by OFO. • Various application strategies of LP reduce the damage caused by OFO to grouper by regulating physiological indicators. • LP's various application strategies enhance grouper stress resistance via cytokine-mediated oxidative stress capacity.