Effect of Dietary Starch Inclusion Rate on Digestibility and Amylase Activity in Arctic charr (Salvelinus alpinus) and Eurasian perch (Perca fluviatilis)

This study investigated digestibility and amylase activity in Arctic charr and Eurasian perch fed different dietary levels of wheat starch. Eurasian perch (190 ± 0.5 g) and Arctic charr (102 ± 0.5 g) were fed one of six iso-nitrogenous diets containing 0, 10, 15, 20, 25 and 30% wheat starch. Each diet was fed to four replicate groups of fish to determine the impact of diet on the apparent digestibility (AD) of dry matter (DM), crude protein, starch, crude fat and energy. At the end of the experiment, tissue samples were collected for assessment of amylase activity in the proximal and distal intestine. The AD of DM, crude protein, starch, crude fat and energy differed between fish species (P<0.001), with on average higher values for all parameters in Eurasian perch than in Arctic charr. Within fish species, there was no effect (P>0.05) of dietary starch level on the AD of DM, crude protein, crude fat and energy. Overall, α-amylase activity correlated with the trends obtained for starch digestibility. The inclusion of wheat starch did not affect amylase activity within species.