Effect of dietary guanidinoacetic acid on growth, hepatic anti-oxidative capacity and muscle energy metabolism in channel catfish (Ictalurus punctatus)

A 8-week feeding trial was conducted to study the effect of dietary guanidinoacetic acid (GAA) on the growth performance, hepatic anti-oxidative capacity and muscle energy metabolism of channel catfish (Ictalurus punctatus). Four isonitrogenous and isocaloric experimental diets with 0 (control diet), 300, 600, and 900 mg/kg GAA (GAA0, GAA300, GAA600, and GAA900) were formulated. The results showed that appropriate dietary GAA could improve the average final body weight (FBW) and weight gain rate (WGR), but not significantly. While the viscerosomatic index (VSI) and intraperitoneal fat ratio (IPF) of experiemental I. punctatus were significantly affected by dietary GAA levels, with the lowest values in GAA300 group. Based on the quadratic regression analysis of IFP and VSI, the optimal dietary GAA level for I. punctatus was 275 mg/kg and 150 mg/kg, respectively. The addition of GAA in diet had no significant effect on moisture content, crude protein, crude fat and ash content of whole fish, as well as the free amino acids and fatty acids in muscle. While the hydroxyproline (HYP) in muscle was significantly increased with the increase of dietary GAA for better muscle quality. Additionally, dietary GAA can improve hepatic anti-oxidative capacity. The total antioxidative capacity (T-AOC) and superoxide dismutases (SOD) activities of fish in GAA300 group were significantly higher than those of the control group. GAA can also improve muscle energy metabolism, and the succinate dehydrogenase (SDH) and pyruvate kinase (PK) activities of fish in GAA300 group were significantly higher than those of the control group. Conclusively, dietary GAA has no significant effect on growth performance and feed utilization of I. punctatus. While 150-300 mg/kg GAA in diet can reduce intraperitoneal fat content and viscerosomatic index, and improve hepatic anti-oxidative capacity and muscle energy metabolism of I. punctatus.