Physiological and Immunological Responses of Nile Tilapia (Oreochromis niloticus) Fed Diets Enriched with Vitex agnus-castus Extract

Abstract

This study investigated the effects of dietary supplementation with Vitex agnus-castus fruit extract on Nile tilapia (Oreochromis niloticus). Two hundred and forty fish were randomly distributed into four groups and fed a basal diet supplemented with 0, 1, 2, or 4 g/kg of extract for 60 days. Results indicated that fish fed 2 and 4 g/kg exhibited significantly higher final weight, weight gain, and specific growth rate, alongside a lower feed conversion ratio compared to the control (P < 0.05). Activities of digestive enzymes including protease, amylase, and lipase, as well as antioxidant enzymes such as superoxide dismutase, catalase, and glutathione peroxidase, were significantly enhanced in all treated groups. The highest values for these parameters were observed at the 2 g/kg level. Furthermore, immune parameters including lysozyme activity, complement activity, and respiratory burst activity were significantly elevated in the treatment groups. The study concludes that dietary supplementation of V. agnus-castus extract at 2 g/kg optimally improves growth, enhances digestion, boosts antioxidant capacity, and strengthens immune function in O. niloticus.