Evaluation of Nutrition of Antarctic Krill Meal as Dietary Protein Source for Flatfishes

Abstract:

In this study we evaluated the contents of major nutrients including amino acids and fatty acids of two krill meals, Antarctic krill meal and hydrolyzed krill meal, and analyzed the muscle samples of five species of flatfishes, Verasper Variegates, Platichthys stellatus, Platichthys biocoloratus, Verasper moseri, and Scophthalmus maximus. The nutritional values of the two krill meals were tested with the essential amino acid index, score of ratio coefficient of amino acid, and relativity of essential amino acids, and the levels of fluorine in the two krill meals were also measured. Sixteen kinds of amino acids were found in muscles of five flatfishes, including seven essential amino acids and four flavor amino acids. The amino acid composition of muscles of the five flatfishes complied the standards of Food and Agriculture Organization of the United Nations/World Health Organization (FAO/WHO). The contents of crude proteins in Antarctic krill meal and hydrolyzed krill meal were 60.84% and 68.60% respectively, which satisfied the standards of the first class products index and the superfine products index. After hydrolysis, the content of crude proteins was significantly increased (P<0.05), whereas the content of crude lipids dropped (P<0.05). The content of ash was unaltered (P>0.05). These results suggested that there was a good balance in the amino acid composition of the two krill meals, and that the relativity of essential amino acids was similar to the fish meal. In addition, the content of fluorine in the hydrolyzed krill meal was significantly lower than that in the Antarctic krill meal (P<0.05). In conclusion, Antarctic krill meal and hydrolyzed krill meal had high nutritional values and potentially could be largely employed in aquaculture feeds.