Abstract

Background:
The exploration of natural dietary supplements to enhance immune function and disease resistance in aquaculture is of significant interest.

Aim:
This study aimed to investigate the capacity of dietary Vitex agnus-castus L. (Chaste Tree; CT) extract to modulate immune function in rainbow trout (Oncorhynchus mykiss).

Methods:
Fish were divided into four cohorts and maintained on isocaloric diets containing 0% (control), 0.5%, 1%, or 2% (w/w) CT extract for 60 days. Key innate immune markers, including blood respiratory burst activity and serum lysozyme activity, were quantified at weeks 4 and 8.

Results:
Supplementation with CT significantly increased (p < 0.05) respiratory burst activity in groups receiving 1% and 2% CT relative to controls. After 8 weeks of feeding, serum lysozyme activity was markedly elevated in fish fed 0.5% and 1% CT.

Conclusion:
These findings indicate that V. agnus-castus extract effectively potentiates crucial innate immune responses in rainbow trout, supporting its prospective application as a functional dietary supplement to enhance health status and disease resistance in aquaculture.

Key words: Vitex agnus-castus L.; Immunostimulant; Respiratory burst; Oncorhynchus mykiss; Aquaculture.