Effect of incorporating increasing levels of dextrin in the diet on the growth and metabolic parameters of mullet (Mugil liza Valenciennes 1836, Mugilidae)
The effects of including increasing levels of dextrin on growth, chemical parameters of blood and glycogen and hepatic triglycerides in the Mugil liza diet were evaluated. The diets were formulated to be isonitrogenated (350 g kg-1) and isolipidic (6 g kg-1) with increasing levels of dextrin (D150: 150 g kg-1; D200: 200 g kg-1; D250: 250 g kg -1; D300: 300 g kg-1; D350 350 g kg-1). The experimental diets were offered until apparent satiety 4 times a day, for 34 days. Each treatment was tested in triplicate with 9 fish per tank (initial weight 4.69 ± 0.31 g), each unit consisting of a fiber tank containing 50L of salt water. The growth parameters and body composition of the mullets did not show significant differences (P> 0.05) between the different treatments.The plasma glucose concentration decreased (P <0.05) when the level of dextrin increased from D250 to D300, but recovered the previous values (in reference to D150) when the fish were fed D350. Glycosylated hemoglobin, proteins, triglycerides and plasma cholesterol did not show significant differences (P> 0.05) between treatments. Hepatic glycogen showed a maximum concentration in treatment D250, followed by D350, D200, D300 and D150 (P <0.05). The concentration of hepatic triglycerides increased (P <0.05) in treatments D300 and D350 when compared to D200. In conclusion, juveniles of Mugil liza can be fed up to 35% dextrin in the diet without deleterious effects on growth, plasma biochemistry and glycogen and hepatic triglycerides.