Effects of the use of feeds containing phytase enzyme from different protein sources on nitrogen and phosphorus discharge of rainbow trout (Oncorhynchus mykiss) juveniles

Document Type: Research Paper


1 Isparta University of Applied Sciences, Faculty of Eğirdir Fisheries, Aquaculture Department, Isparta, Turkey

2 Ministry of Food, Agriculture and Livestock, Mediterranean Fisheries Research Institute, Antalya, Turkey


In this study, the effects of diets (D1-3) including fish meal (FM), hazelnut meal (HM), soybean meal (SM), and phytase enzyme [- (0),+(1000 FTU)]  in varying rates (D1-, D1+; D2-, D2+; D3-, D3+)  were examined on nitrogen and phosphorus discharge based on the nutrition of rainbow trout (Oncorhynchus mykiss) juveniles. The study was conducted in tanks with 3 replicates for each group. In this trial, it was found that the differences among total-particle nitrogen, particle phosphorus, and total solid waste values released from the rainbow trout groups were insignificant; however, the differences between the values of total-dissolved phosphorus and dissolved nitrogen released were found significant (p<0.05).The interactions among the factors were determined as insignificant (p>0.05). Moreover, although there were increases in the total and dissolved phosphorus and dissolved nitrogen discharge in all groups fed with diets including phytase, the particle phosphorus discharge decreased (p<0.05). Based on the decrease in the amounts of hazelnut meal and soybean meal used in the diets, it was determined that there was a decrease in the amount of dissolved phosphorus released to the environment; besides, it was determined that it led to an increase in the amount of released dissolved phosphorus in all groups fed with diets containing phytase enzyme (p<0.05).