Exogenous enzyme pretreatment improves utilization of high-carbohydrate diets in rainbow trout (Onchorhynchus mykiss): effects on growth, digestibility, fillet quality, and gene expression.

Exogenous enzymes are used to enhance ingredient digestibility, overall fish growth, and feed utilization; however, different administration methods have not been extensively studied. In this study, a mixture of carbohydrases (α-amylase, cellulase, xylanase, and β-glucanase) was applied before (at B3, B6, B12, and B24 hours), during (D), or after (A) the production of high-carbohydrate diets (33% carbohydrates) to assess their effects on the growth and feed utilization of rainbow trout. The enzymes were added to the diets at the minimum required levels, determined by a reducing sugar test with dinitrosalicylic acid (DNS) based on the available wheat flour and soybean meal in the diet.