Effects of Lactobacillus plantarum supplementation on growth performance, digestive enzyme activity, antioxidant capacity, immune response, and intestinal health in red claw crayfish (Cherax quadricarinatus)

The objective of the present study was to evaluate the effects of gradient addition of Lactobacillus plantarum to feed on growth performance, digestive enzyme activities, antioxidant capacity, immune response, and intestinal health of red claw crayfish. The experiment comprised four distinct treatment groups: control group (CK, 0 g·kg⁻¹), low concentration group (LL, 0.10 g·kg⁻¹), medium concentration group (ML, 1.00 g·kg⁻¹), and high concentration group (HL, 10.00 g·kg⁻¹). Three biological replicates were established in each group, with each replicate containing 50 juvenile crayfish at the beginning of the experiment, with initial body weights ranging from 0.13 ± 0.01 g. The experiment spanned 70 days. The experimental results showed that different concentrations of Lactobacillus plantarum significantly increased (p < 0.05) the weight gain rate, specific growth rate, length gain rate, hepatosomatic index, survival rate, and intestinal morphology in red claw crayfish. Additionally, the treatment significantly enhanced (p < 0.05) the activities of lipase, tryptase, and α-amylase in the intestine and hepatopancreas, and significantly up-regulated (p < 0.05) the expression of key genes in the hepatopancreas related to antioxidant defense, immunity, and stress response, including superoxide dismutase, glutathione peroxidase, glutathione, catalase, anti-lipopolysaccharide factor, crustacean hyperglycemic hormone, serine protease inhibitors, lysozyme, alkaline phosphatase, down syndrome cell adhesion molecule, antibacterial peptides, and heat shock protein 70. In conclusion, the addition of Lactobacillus plantarum to the feed of red claw crayfish significantly enhanced its growth performance, digestive enzyme activities, antioxidant capacity, and immune response capacity and positively affected its intestinal health. The optimum addition of Lactobacillus plantarum under this experiment was determined to be 1.00 g·kg⁻¹ .