Effects of dietary creatine levels on the growth, muscle energy metabolism and meat quality of spotted seabass (Lateolabrax maculatus) fed low-fishmeal diets

Abstract

The study was performed to evaluate the effects of dietary creatine (CR) levels on the growth, muscle energy metabolism and meat quality of spotted seabass (Lateolabrax maculatus) fed low-fishmeal diets. The experimental diets were formulated with 15% fishmeal, and contained five creatine levels of 0.03%, 0.07%, 0.12%, 0.21% and 0.39%. Spotted seabass (initial body weight: 4.38 ± 0.06 g) were randomly allocated into 15 tanks (20 fish per tank) and fed twice daily for 8 weeks. With increasing dietary CR levels, the final body weight (FBW) and weight gain (WG) significantly increased, and the peak occurred in the 0.21% group. Second-order polynomial regression analysis showed that the optimum CR supplementation level based on WG was 0.25% for spotted seabass. With the increase in dietary CR levels, anaerobic glycolysis (the activities of lactic dehydrogenase and pyruvate kinase) in fish muscle was significantly reduced. The energy reserve (the content of ATP and activity of creatine kinase) was significantly increased to promote the pH value at 48 h postmortem with increasing CR levels. Water holding capacity increased as dietary CR levels increasing from 0.03% to 0.39%. The mRNA expression of myog, myod, myf5, mef2c, mstn, capn1 and capn2 was upregulated, but the mRNA expression of cast was downregulated with increasing CR levels from 0.03% to 0.39%. In conclusion, dietary CR supplementation promoted the growth performance of spotted seabass fed low-fishmeal diets, and the optimum creatine level was 0.25%. Dietary CR supplementation increased energy reserve and deceased anaerobic glycolysis at 48 h postmortem and enhanced meat quality.