Dietary supplementation with taurine improves ability to resist ammonia stress in hybrid snakehead (Channa rnaculatus female x Channa argus male)

This study determined the effect of dietary supplementation with taurine on plasma biochemical indices, blood cell apoptosis rate, survival rate and expression of catalase (CAT), glutathione reductase (GR) and heat-shock protein 70 (HSP70) gene in juvenile hybrid snakehead under ammonia stress. Six diets were formulated to conthin 0, 3.0, 6.0, 9.0, 12.0 and 15.0 g/kg taurine. Each diet was fed to triplicate groups of fish in cylindrical tanks. After 8 weeks of feeding, 20 fish per tank were exposed to ammonia stress (total ammonia nitrogen = 200 mg/L) for 48 hr. The results showed that, after ammonia stress, plasma alkaline phosphatase (ALP), triacylglycerol (TG) levels and survival rate significantly decreased (p < 0.05) while plasma alanine aminotransferase (ALT), aspartate aminotransferase (AST), urea nitrogen (BUN), respiratory burst, blood cell apoptosis rate, hepatic CAT, GR and HSP70 mRNA expression levels significantly increased (p < 0.05). On the other hand, dietary supplementation with taurine significantly reduced levels of BUN, respiratory burst and blood cell apoptosis rate. Supplemented groups significantly increased relative mRNA expression of hepatic CAT, GR and HSP70 as well as increased survival rate (p < 0.05). These results indicated that dietary supplementation with taurine improved ability to resist ammonia stress in hybrid snakehead.