Clostridium butyricum (CB) is a strictly anaerobic gram-positive probiotic. In this study, CB strain (LV1) was extracted from the intestine of Litopenaeus vannamei for preparing CB lyophilised powder (CBLP, 5.6 × 108 CFU/g) by freeze-drying method, with the aim to explore the effect of CB LV1 lyophilised powder on the growth, intestinal microbiota, and immunity of Litopenaeus vannamei after substitution of fishmeal with cottonseed protein concentrate (CPC). Six isonitrogenous and isolipid diets were formulated with 25% fishmeal in the positive control (FM) and 40% fishmeal replaced by CPC in the negative control (CBLP 0). CBLP was added to the CBLP 0 group at 3 × 105 CFU/g (CBLP 1), 1.2 × 106 CFU/g (CBLP 2), 4.8 × 106 CFU/g (CBLP 3), and 1.92 × 107 CFU/g (CBLP 4), respectively. The results showed that the CBLP 3 group had the highest weight gain rate and specific growth rate (P > 0.05). Serum superoxide dismutase and acid phosphatase activities were remarkably enhanced in the CBLP 2, CBLP 3, and CBLP 4 groups (P < 0.05). CBLP supplementation improved the intestinal digestive enzyme activity. The addition of CBLP optimized the structure of the intestinal microbiota, increased the beneficial bacteria, and reduced the potentially pathogenic bacteria. Chao1, ACE, and Sob indices were elevated in the CBLP 2, CBLP 3, and CBLP 4 groups (P < 0.001). Relish, PO, eIF4E1α, and IGF1 gene expressions were remarkably elevated in the CBLP 3 group (P < 0.01). CBLP further improved the intestinal morphological structure and enhanced the disease resistance. Muscle phenylalanine, histidine, and tyrosine contents were remarkably elevated in the CBLP 1 and CBLP 2 groups (P < 0.05). In conclusion, supplementation of CBLP in CPC basal diets improved the growth, intestinal microbiota, and immunity of Litopenaeus vannamei. Binary regression analysis of SGR indicated that the appropriate addition level of CBLP was 8.79 × 106 CFU/g.
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