Dietary Litsea cubeba essential oil enhances growth, immunity, and intestinal health in channel catfish

This study investigated the effects of dietary supplementation with Litsea cubeba essential oil (LEO) on growth performance, immune function, intestinal health, and microbiota composition in channel catfish (Ictalurus punctatus). An eight-week feeding trial was conducted with 750 fish (60.00 ± 0.50 g) assigned to five diets: 0 (CON), 100 mg/kg (LEO100), 200 mg/kg (LEO200), 400 mg/kg (LEO400), and 800 mg/kg (LEO800). The LEO100 and LEO200 groups showed significant improvements in growth performance, immune response (C3, C4, and ACP levels), and digestive enzyme activities (amylase, lipase, and trypsin). Gene expression analysis revealed an upregulation of genes related to intestinal barrier integrity (zo-1, zo-2, and occludin), immunoregulatory cytokines (tgf-β1, tgf-β2, tgf-β3, and il-10), and key transcriptional regulators nf-κb and stat3). Conversely, pro-inflammatory mediators (il-8, il-1β, and tlr5) were significantly downregulated. In the LEO100 and LEO200 groups, the protein expression of TNF-α and NF-κB was elevated. Additionally, intestinal morphology (villus height, muscle thickness, and goblet cell count) and beneficial microbiota (Lactococcus and Plesiomonas) were enhanced in the LEO100 and LEO200 groups. These results demonstrate that dietary supplementation with LEO at 100–200 mg/kg improves growth performance, immune function, and intestinal health in channel catfish, making it a promising natural feed additive for aquaculture.