Physicochemical property optimization and nutrient redistribution in the muscle of sub-adult grass carp (Ctenopharyngodon idella) by conjugated linoleic acid

We studied the effects of conjugated linoleic acid (CLA) on the amount of nutrients, flavour substances, and healthcare fatty acids, the physicochemical properties, and the potential molecular mechanisms in the muscles of sub-adult grass carp (Ctenopharyngodon idella). Fish were fed graded levels of CLA (0.0, 3.1, 6.4, 9.6, 12.7, and 15.9 g/kg diets) for 60 days. Protein, glutamic acid, alanine, inosine monophosphate (IMP), eicosapentaenoic acid (EPA; 20:5n-3), docosahexaenoic acid (DHA; 22:6n-3), and total CLA contents (p < 0.05) increased in CLA 3.1 ∼ 12.7, 6.4 ∼ 9.6, 6.4 ∼ 9.6, 6.4 ∼ 15.9, 3.1 ∼ 9.6, 3.1 ∼ 9.6, and 3.1 ∼ 15.9 g/kg diet, respectively (p < 0.05). In addition, optimal CLA significantly increased pH(24), shear force, collagen content, and myofibre density in the muscle (P < 0.05); however, it decreased myofibre diameter (p < 0.05). We concluded that 6–9 g/kg CLA in the diet could improve the flesh quality of sub-adult grass carp.