Enhancing farmed striped catfish ( Pangasianodon hypophthalmus ) robustness using dietary β-glucan

Abstract β-glucan is a well-documented feed additive for its potent immunostimulatory properties in many farmed fish species. This study examined how it can also be a promising growth promoter, modulate antioxidant enzyme activities, and act as an anti-stress agent in striped catfish ( Pangasianodon hypophthalmus ). A 12-week feeding experiment was untaken to determine the effects of dietary β-glucan supplementation at graded levels (0, 0.5, 1.0, and 1.5 g kg -1 ). Measured indicators suggest that a dietary inclusion level of 1.5 g kg -1 β-glucan gave the highest positive responses: weight gain (120.10 g fish -1 ), survival (98.30 %), and lower FCR (1.70) ( P <0.05). Whole body proximate analysis had only revealed that crude protein was significantly affected by the dietary inclusion of β-glucan ( P <0.05), with the highest protein content (19.70 %) being in fish that were fed with 1.5 g kg -1 β-glucan. Although other inclusion levels (i.e., 0.5 and 1 g kg -1 ) of β-glucan did not enhance body protein content ( P >0.05). The assessment of fatty acid composition in muscle, liver, and adipose tissues showed modifications with the inclusion of β-glucan. Antioxidative-related enzyme activities (inc. catalase, glutathione peroxidase, and superoxide dismutase) that were measured in the liver had higher levels when fed with β-glucan inclusion diets ( P <0.05). Following the feed trial, fish were subjected to crowding stress treatment. It was subsequently found that catfish fed with β-glucan-based diet groups had lower levels of blood stress-related indicators compared to the control group with no dietary β-glucan. The use of 1.5 g kg -1 of dietary β-glucan resulted in the lowest measured levels of cortisol (43.13 ng mL -1 ) and glucose (50.16 mg dL -1 ). This study has demonstrated that the dietary inclusion of β-glucan can have functional benefits beyond the immunological enhancements in striped catfish. Furthermore, its use can increase production levels and mitigate the stress associated with intensive farming practices.