Effect of dietary dextrin levels on growth,activities of digestive enzyme and blood biochemical indices of juvenile obscure puffer(Takifugu obscurus)

Abstract

A feeding trial was conducted to determine the effect of dietary dextrin level on growth,activities of digestive enzyme and blood biochemical indices of juvenile obscure puffer,Takifugu obscurus.Five iso-nitrogenous(42%)and iso-lipidic(9%)diets containing graded levels of dextrin(10%,15%,20%,25% and 30%)were prepared.The fish[average weight(10.25±0.51 g)]were stocked in triplicate tanks during a feeding period of 60 days.The results showed that best specific growth rate and feed efficiency occurred for fish fed the diet with dietary dextrin level at 25%.Viscerosomatic index and hepatosomatic index of 30% group were significantly higher than those of 10% group(P0.05),meanwhile liver lipid content of 30% group was also significantly higher than other groups(P0.05).Liver glycogen and total amino acids content in plasma of 10% group were significantly lower than those of other groups(P0.05).Compared with the 10% and 15% groups,amylase activity in hepatopancreas and intestine of other groups was significantly increased(P0.05),while trypsin activity in hepatopancreas of the 30% group decreased significantly(P0.05);total cholesterol and triglycerides content in plasma of the 25% and 30% groups increased significantly(P0.05),while blood urea nitrogen in plasma of other groups decreased significantly(P0.05).Red blood cell counts of 15% and 20% groups were significantly higher than other those of groups(P0.05),while apoptosis ratio,reactive oxygen species and calcium ions content of 30% group were significantly higher than those of other groups(P0.05).However,plasma glucose concentration,aspartate aminotransferase and alanine aminotransferase activity as well as lipase activity in hepatopancreas and intestine of obscure puffer were not affected by dietary dextrin levels.The present results showed that the optimum dextrin level in diets is at 20%-25% for juvenile obscure puffer under the present research conditions.