Comparative study of the effects of two high - carbohydrate diets on growth and hepatic carbohydrate metabolic enzyme responses in juvenile gıft tilapia ( oreochromis niloticus)

Özet

This study aimed to compare the effect of two high -carbohydrates diets on growth, activity and gene expression of hepatic metabolic enzymes in GIFT tilapia juveniles (Oreochromis niloticus ). Two isonitrogenous (28 % crude protein) and isolipidic (5 % crude lipids) diets were formulated to contain 4 0% of wheat starch (WS) or glucose (GLU). Diets were assigned to triplicate group s of 30 fish (in itial weight: 11.26g) for 45 days. At the end of trial, SGR, feed intake, feed efficiency, HSI, VI and liver glycogen levels were not significantly influenced by dietary carbohydrates. Plasma glucose was higher in fish fed the GLU diet than in the WS diet. No significant effect of dietary carbohydrates source on GK and G6Pase activities were present, however, these activities were significant higher than the initial levels. In contrast, higher G6PD activities were recorded in GLU group than in the WS group on d ay 45. Data on gene expression showed that G6Pase and G6PD but not GK was affected by dietary carbohydrates on d ay 45 ; the levels of G6Pase and G6PD mRNA in GLU group were significantly higher than in WS group. Overall, dietary high glucose levels was utilized well as energy source by GIFT tilapia juveniles, and seem to be more effective in increasing liver lipogenic activities .