Effect of dietary betaine and choline association on lipid metabolism in blunt snout bream fed a high‐fat diet

This study established the effects of betaine and choline association on lipid metabolism of blunt snout bream ( Megalobrama amblycephala ) fed high‐fat diet (HFD). Fish (43.73 ± 0.13 g) were randomly distributed into 21 cages in seven groups (three replicates) and fed with control diet, HFD and HFD+ betaine and choline associated at different levels (16, 12, 8, 4 or 0 g/kg betaine and 0, 2, 4, 6 or 8 g/kg choline), designated as diet 1, diet 2, diet 3, diet 4, diet 5, diet 6 and diet 7 respectively for 8 weeks. Fish fed diet 4 obtained higher final body weight, weight gain and specific growth rate whereas feed conversion ratio showed the opposite trend compared to those fed HFD. Higher plasma levels of cholesterol, triglycerides, low‐density lipoprotein tHcy and low levels of high‐density lipoprotein, S‐adenosylmethionine, S‐adenosylhomocysteine were observed in fish fed HFD; the opposite was true for fish fed diet 4. Also, a lower liver superoxide dismutase, glutathione peroxidase activities and a higher malondialdehyde content were observed in fish fed HFD. This effect was reversed with fish fed diet 4. The transcription of Betaine–homocysteine S‐methyltransferase1, glycine N‐methyltransferase and monoacylglycerol O‐acyltransferase 1 were upregulated in fish fed HFD. The opposite trend was observed in fish fed diet 4. In conclusion, betaine and choline associated diets can benefit growth and lipid metabolism of blunt snout bream fed HFD.