Feeding faba beans (Vicia faba L.) to grass carp (Ctenopharyngodon idellus) increases muscle compactness but decreases growth and motility. The lipid metabolism of grass carp was examined to assess potential effects of feeding faba beans on physiological properties using a total of 180 fish. The treatment group was fed faba beans for 120 days and a commercial diet for another 30 days. The control group received a commercial diet for 150 days. Fish were sampled every month. Weight gain was significantly lower in the treatment group than in the control. Hardness, springiness, chewiness, cohesiveness, and gumminess of the dorsal muscle increased significantly with the feeding faba beans from 30 to 120 days, which was not reversed by the subsequent feeding of commercial diet. Fat accumulation increased significantly in the treatment group as suggested by the condition factor, viscera index, hepatopancreatic index, and intraperitoneal fat index (IPFI), hepatopancreas, and muscle fat content but was not affected by subsequent feeding with the commercial diet. Serum triglyceride and total cholesterol levels were significantly reduced in the experimental diet group. In the hepatopancreas and intraperitoneal fat IPF, monounsaturated fatty acids showed significantly higher content in faba bean feeding fish, whereas polyunsaturated fatty acid content showed the reversed pattern. In the hepatopancreas, the activities of the lipogenic enzymes malate dehydrogenase and glucose 6-phosphate dehydrogenase were higher in the treatment than in the control group. Moreover, the treatment group showed lower mRNA levels of carnitine palmitoyltransferase-1. Overall, our results clearly demonstrate increasing lipid accumulation in the viscera of faba bean-fed grass carp.
Keywords: Crisp grass carp; Ctenopharyngodon idellus; Faba bean; Lipid metabolism.