Protective Effects of Dietary Etlingera elatior (Jack) Bud Flower Powder against Edwardsiella tarda Infection in African Catfish, Clarias gariepinus

Abstract

This study investigates the impacts of dietary Etlingera elatior (Jack) bud flower powder (EE) supplementation on the growth and health status of African catfish, Clarias gariepinus. Each treatment group received different formulated diets: basal diet without EE (control), basal diet + 1% EE (EE1), basal diet + 2% EE (EE2), basal diet + 3% EE (EE3), and basal diet + 4% EE (EE4). After an 8-week feeding trial, fish supplemented with dietary EE exhibited significantly improved growth performance, such as weight gain (WG; 1,251.4%-1,604.3%; p<0.0001), specific growth rate (SGR; 2.02%-2.20%; p<0.0001), and final weight (FW; 141.7-178.9 g; p<0.0001) than the control group (WG: 1,192.0%, SGR: 1.98%, and FW: 136.1 g), particularly EE2 and EE3. Furthermore, EE-treated fish recorded significantly lower feed conversion rate (FCR; 1.19-1.53; p<0.0001), viscerosomatic index (VSI; 3.40%-4.50%; p<0.0001), and hepatosomatic index (HSI; 3.13%-4.40%; p<0.0001) than the control (FCR: 1.59, VSI: 5.48%, and HSI: 4.75%), particularly EE2 and EE3. The EE-treated fish also had significantly higher white blood cell (WBC) count (124.6-148.6/μL; p<0.0400), red blood cell (RBC) count (2.43-4.03 × 103/μL; p<0.0002), hemoglobin (HGB) concentration (6.27-7.87 g/dL; p<0.0160), and hematocrit (HCT; 26.8%-38.7%; p<0.0200) compared to the control (WBC count: 112.1/μL, RBC count: 2.17 ×103/μL, HGB concentration: 5.60 g/dL, and HCT: 23.7%), with the highest being EE2 and EE3. Dietary EE diets enhanced digestive enzyme activities, including amylase (p<0.0090), protease (p<0.0040), and lipase (p<0.0060), significantly (p<0.05) than the control, where EE2 and EE3 demonstrated the highest activities. The EE supplementation also significantly improved the fish's antioxidative responses, particularly catalase (CAT; p<0.0100), glutathione peroxidase (GPx; p<0.0300), and superoxide dismutase (SOD; p<0.0100) in EE2 and EE3. Similarly, the cumulative survival rate of EE2 (66.7% ± 5.77%) and EE3 (66.7% ± 5.77%) were significantly (p<0.0001) higher than other groups post-Edwardsiella tarda challenge. Therefore, this study findings highlighted the potential benefits of EE as a feed additive to boost the production in African catfish farming.