Wheat gluten and potato protein concentrate — Promising protein sources for organic farming of rainbow trout (Oncorhynchus mykiss)

In contrast to potato and other plant proteins, wheat gluten does not require complex and costly purification and may thus be utilized in aquaculture diets according to aquaculture guideline EC 710/2009. Therefore, a feeding trial was conducted to evaluate the effect of various combinations of wheat gluten (WG) and potato protein concentrate (PPC) in nutrition of rainbow trout (Oncorhynchus mykiss). Seven isonitrogenous (459±6g CP kg−1) and isoenergetic (21.4±0.1MJkg−1) diets were formulated to contain varying levels of wheat gluten and potato protein concentrate (6/27; 9/24; 11/21; 14/19; 17/16; 19/13 as proportion of WG/PPC in % of the diet) at constant fishmeal replacement level of 56% on protein level and one fish meal diet served as control. Experimental diets were fed over a period of 56days to triplicate experimental groups until apparent satiation. Growth performance showed no significant differences between all feeding groups at the end of the experimental period. No influences on health and nutritional status were documented between the treatments in the body composition and blood parameter. The wheat gluten and PPC as fish meal replacement in organic diets for rainbow trout revealed positive and equal results for use in the inclusion level of the presented trial. ► This study evaluated the effect organic certified proteins in rainbow trout nutrition. ► Various combinations of wheat gluten and PPC were used. ► Growth and growth performance revealed good results within all groups. ► Good nutritional status revealed no negative impact of wheat gluten or PPC in general. ► A wheat gluten inclusion up to 19% exhibits positive results for organic diets.