Effects of Plant-Derived Extracts (Tea Polyphenols + Oregano Oil) on Immune Function and Vibrio Control of Litopenaeus vannamei

Abstract

This study assessed a compound plant-derived extract (CPE: tea polyphenols + oregano oil, 3:1 mass ratio) on Litopenaeus vannamei immune function, gut health, and Vibrio control via a 10-week experiment (five groups: control, 0.1%/0.3%/0.5% CPE, 0.02% oxytetracycline (AB); 250 shrimp/tank, initial weight 0.85±0.07 g) followed by a 7-day Vibrio parahaemolyticus challenge (1×10⁷ CFU/mL). The 0.3% CPE group exhibited optimal effects: total hemocyte count (+42.2%), phenoloxidase (+55.0%), and lysozyme (+68.7%) activities (P<0.05), gut villus height increased by 38.5%, and gut Vibrio abundance reduced by 61.4% vs. control. Its challenge survival rate (78.5±3.2%) was 2.3-fold higher than control (34.2±2.8%) and 18.2% higher than AB (66.4±3.0%) (P<0.05). High-throughput sequencing revealed enriched beneficial gut bacteria (Lactobacillus, Bifidobacterium) and upregulated immune-related KEGG pathways. Results confirm 0.3% CPE as an effective antibiotic alternative for sustainable shrimp culture.

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