O. Demir - Aquaculture and Fish Feeding
A. Yilayaz - Mediterranean Fisheries Research Institute,Ministry of Food, Agriculture and Livestock, Antalya, Turkey

In this study, the effects of diets (D۱-۳) including fish meal (FM), hazelnut meal (HM), soybean meal (SM), and phytase enzyme [- (۰),+(۱۰۰۰ FTU)]  in varying rates (D۱-, D۱+; D۲-, D۲+; D۳-, D۳+)  were examined on nitrogen and phosphorus discharge based on the nutrition of rainbow trout (Oncorhynchus mykiss) juveniles. The study was conducted in tanks with ۳ 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<۰.۰۵).The interactions among the factors were determined as insignificant (p>۰.۰۵). 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<۰.۰۵). 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<۰.۰۵).   

Diets protein, Waste, Dissolve, Enzyme, Fish