Dietary organic acid salts mitigate plant protein induced inflammatory response and improve humoral immunity, antioxidative status and digestive enzyme activities in yellowfin seabream, Acanthopagrus latus

An eight-week research was conducted to investigate the effects of single or combined administration of sodium propionate (Na-P) and sodium acetate (Na-A) on the performance of yellowfin seabream (Acanthopagrus latus) juveniles (6.5 ± 0.3 g). A plant protein (PP)-rich diet was supplemented with sole or blends of organic acid salts (OAS) namely Na-P and Na-A to design six experimental feeds including control (without OAS), Na-P5 (5 g/kg Na-P), Na-P10 (10 g/kg Na-P), Na-A5 (5 g/kg Na-A), Na-A10 (10 g/kg Na-A) and Na-P + A (5 g/kg Na-P + 5 g/kg Na-A). Except for Na-A5 group, the other OAS-supplemented treatments had higher growth and feed efficiency ratio than the control (p < .05). The inclusion of OAS in the experimental feeds pronouncedly enhanced plasma lysozyme and alternative complement pathway activities compared to the control. Furthermore, fish fed on the OAS-supplemented diets had greater catalase and glutathione peroxidase activities in the liver than the control (p < .05). Total antioxidant capacity in the liver of fish fed on the OAS-supplemented diet also was higher than the control. Fish fed on the OAS-supplemented diets had higher pepsin, trypsin and lipase activities than the control. The insulin-like growth factor 1 (IGF-1) gene expression was remarkably down-regulated in the liver of fish fed on the OAS-supplemented diets compared to the control especially in groups fed on the Na-P10 and Na-A10 diets. The greatest IGF-1 gene down-regulation level in the gut was in fish fed on the Na-P5 and Na-P10 diets. The interleukine-1β in the gut was remarkably up-regulated in the control compared to the other groups (p < .05). The lactic acid bacterial colonies count in the gut of the control was lower than the OAS-supplemented groups. Based on the findings of the present study, supplementing PP-rich diets with 10 g/kg Na-P or blends of Na-P (5 g/kg) and Na-A (5 g/kg) beneficially alleviated inflammatory responses and improved immune parameters and digestive capacity in yellowfin seabream juveniles.