Dietary supplementation with Kelussia odoratissima extract improves growth performance and modulates intestinal cytokine‐related gene expression in zebrafish ( Danio rerio )

Abstract

Kelussia odoratissima (wild celery) is an endemic medicinal plant containing diverse bioactive phytochemicals; however, its potential as a dietary additive in fish has not previously been investigated. This study evaluated the effects of dietary hydroethanolic K. odoratissima extract (KOE) on growth performance, feed utilization, and intestinal cytokine‐related gene expression in zebrafish ( Danio rerio ). A total of 600 fish (initial body weight: 210 ± 10 mg) were randomly allocated to 15 tanks (three replicate tanks per treatment) and fed five experimental diets supplemented with 0, 2.5, 5, 10, or 15 g KOE kg ⁻¹ diet for 56 days. Dietary KOE significantly improved growth performance and feed utilization ( p  < 0.05). Fish fed 10 g KOE kg ⁻¹ exhibited the highest final body weight (660 ± 10 mg), specific growth rate (2.10% day ⁻¹ ), and protein efficiency ratio (1.29), together with the lowest feed conversion ratio (1.53). Quadratic regression suggested that dietary inclusion levels of approximately 10–11 g KOE kg ⁻¹ were associated with the greatest biological responses under the present experimental conditions. Survival remained high (94–100%) and did not differ significantly among treatments ( p  > 0.05). Dietary KOE upregulated intestinal tnf‐α and il‐1β expression while downregulating il‐10 and tgf‐β1 , indicating modulation of intestinal cytokine‐related gene expression. These transcriptional responses should not be interpreted as direct evidence of enhanced immune function. Overall, dietary KOE improved growth performance and modulated intestinal cytokine‐related gene expression in zebrafish. Further studies incorporating functional immune assessments, histopathology, and validation in commercially important aquaculture species are required before practical applications can be recommended.