How Do Plant Protein Based Diets Change Cod Production and COD/N Ratios for Denitrification on Internal Carbon Sources in RAS?

摘要

Changing diet composition from fish meal-based protein sources to plant-based protein sources will affect the amount and composition of waste produced in aquaculture operations. Plant-based diets and the inherent increase in fiber content may lead tolower digestibility and an increased production of organic solid waste, measured as chemical oxygen demand (COD). An increase in COD production can be beneficial if COD/N-ratios are limited for denitrification on internal COD sources. Denitrification isa valuable tool to control nitrate, reducing water exchange and nutrient emissions and is often limited by COD availability. However, fibers are generally considered as substrates of low degradability and could be a limiting a factor for denitrification.Current knowledge gaps in this field of research call for a closer investigation of the composition of solid waste, its fiber fractions and the resulting effects on COD/N-ratios and denitrification potential in RAS. The presented research assessed the impact of a plant protein-based diet on the production, composition and denitrification potential of the solid COD waste fraction of rainbow trout (Oncorhynchus mykiss) cultured in a RAS. The goal was to determine COD and N mass balance, COD/N ratios anddenitrification potential.