Enhancing Tilapia Immunity at a Cold Suboptimal Temperature: Efficacy of a Combined β-Glucan, Citral, and Eugenol Diet

Abstract

Abstract A 60-day feeding trial was conducted to evaluate the impact of dietary β-glucan in combination with citral and eugenol on the growth, whole body composition, and innate immunity of Nile tilapia (Oreochromis niloticus) weighing 9.16 g, under cold suboptimal temperatures (20ºC). The treatments included a control (Co); β-glucan (G) at 1.0 g/kg/diet; citral and eugenol (CE) at 0.5 g/kg each; and a combination of β-glucan, citral, and eugenol (GCE) at the same concentrations (1.0, 0.5 and 0.5 g/kg, respectively). Although no significant differences were observed in growth parameters post-trial, proximate analysis indicated an increase in body protein and a decrease in body fat content in the GCE group compared to the Co and G groups, respectively. Enhanced respiratory burst activity of blood leukocytes and myeloperoxidase activity were recorded in the GCE group, indicating improved innate immune responses. Serum complement hemolytic activity was significantly higher in the G group, with no additional benefits from the CE or GCE treatments. Furthermore, the G and GCE groups displayed increased serum lysozyme activity when compared to the control. These findings suggest that the combination (GCE) of these feed additives may offer a beneficial strategy for promoting health in tilapia reared under stressful conditions.

Keywords

• cold stress
• feed additive
• Oreochromis niloticus
• phytochemical, prebiotic