Effects of dietary betaine in allogynogenetic gibel carp (Carassius auratus gibelio): Enhanced growth, reduced lipid deposition and depressed lipogenic gene expression

A 10-week feeding experiment was conducted to evaluate the effects of supplemental betaine on growth performance, body composition and lipid deposition in allogynogenetic gibel carp. Four isoproteic (37% crude protein) and isolipidic (5% crude lipid) artificial diets with 0%, 0.08%, 0.4% and 2% betaine supplementation were formulated, and named VB0, VB0.08, VB0.4 and VB2, respectively. Each diet was fed in triplicate to fish about 10g in weight. The results showed that 0.4% betaine supplementation significantly improved growth performance and reduced lipid content in the hepatopancreas, muscle and the whole body compared with the control group. Moreover, both fatty acid synthase and acetyl-CoA carboxylase, two important lipogenic genes, showed significantly lower expression in the VB0.4 group than in the control group, and a strong correlation was detected between lipid content and mRNA expression levels for FAS and ACC in the hepatopancreas. Taken together, appropriate (0.4%) betaine supplementation in the diet not only improved growth, but also reduced lipid deposition in allogynogenetic gibel carp, probably by diminishing lipogenic gene expression.