Preliminary evaluation of nutritional differences of grass carp (Ctenopharyngodon idella) under two pond culture models

In order to understand the nutritional differences of grass carp cultured in traditional ponds and circulatory systems in ponds, a comparative study was conducted on nutritional components and nutritive quality between pond-and recirculating water system-reared grass carp; fish were fed with the same commercial diet. The results showed that pond group contained significantly higher moisture, crude fat, viscerosomatic index (VSI), pH reduction and drip loss, and lower crude protein and antioxidant function than the recirculating water system group. The constitutional ratio of essential amino acids met the Food and Agriculture Organization of the United Nations/Word Health Organization (FAO /WHO) standards and the content of Lys was the highest in essential amino acids in two culture models. However, the content of total amino acids (∑TAA), total delicious amino acids (∑DAA) and total sweet amino acids (∑SAA) in pond group were significantly lower than those of recirculating water system group. According to nutrition evaluation in amino acids score (AAS) and chemical score (CS), the first limiting amino acids were Val in two culture models. The contents of ∑n-3PUFA and ∑n-6PUFA in pond group were significantly higher than those of recirculating water system group, while contents of EPA + DHA in pond group were significantly lower than those of recirculating water system group. In conclusion, the nutritional composition of grass carp is reasonable; moreover, the recirculating water system culture is superior to pond culture in nutrition and flavor of grass carp.