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

Abstract

In this study, the effects of diets (D_1-3) including fish meal (FM), hazelnut meal (HM), soybean meal (SM), and phytase enzyme [- (0),+(1000 FTU)] in varying rates (D_1-, D₁₊; D_2-, D₂₊; D_3-, D₃₊) were examined on nitrogen and phosphorus discharge based on the nutrition of rainbow trout (<em>Oncorhynchus mykiss</em>) 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 (<em>p </em><0.05).The interactions among the factors were determined as insignificant (<em>p </em>>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 (<em>p </em><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 (<em>p </em><0.05).