Effects of different ratios containing hazelnut meal, soybean meal, fish together with phytase enzymes in the diets on the rainbow trout (oncorhynchus mykiss) juveniles

In this study, the rainbow trout (Oncorhynchus mykiss) juveniles were feed with containing different ratio of fish meal (FM), different ratio hazelnut meal (HM) and soybean meal (SM) ( in the crude protein of diet: D1= 30% FM + 35% HM +35% SM; D2= 40% FM+ 30% HM+ 30% SM; D3= 50 %FM+ 25% HM+ 25% SM) together with having different ratio of phytase (without enzymes "-" D1-, D2-, D3- adding phytase "+" 1000 FTU, D1+, D2+, D3+), isonitrogenously six ( D1-, D1+, D2-, D2+, D3-, D3+) experiment diets using. Effects of these diets on the rainbow trout juveniles' development, body chemical compositions, organ indexes, feed digestibility, nitrogen and phosphorus release were investigated and aimed. The study was carried out on in 6 different groups, including 3 replicates and 20 (initial mean body weight= (27,82 ±0,04 g) fish distributed randomly in each group (18 trial tanks). The experiment period was 75 days, and 2% of the daily body weights were fed, and the measurement were carried out every 15 days. Final weight, feed consumption, feed conversion ratio, specific growth ratio and the protein efficiency ratio of the trial groups were calculated as 52.8-64.3g, 64.1-72.1g/fish, 1.12-1.22, 1.42-1.6% and 1.79-2.0, respectively. Dietary protein source had a significant effect on these parameters (P <0.05). Dietary protein source had a significant effect on these parameters (P <0.05). The dietary factors did not produce a significant effect on the organ indexes, body chemical composition, digestibility ratios of diets in the fish (P>0.05). But phytase enzyme affected significantly the dietary phosphorus ratio and the digestible energy ratio (P<0.05). Values of viscerosomatic index, hepatosomatic index and condition factor in trial groups were calculated as 12,9-14%, 1,17-1,40 and 1,40-1,45, respectively. Final dry matter, crude ash, crude lipid, crude protein of diets and phosphorus components in fish body were found to be 30,7-31,8%, 2,2,2,3,3%, 11,8-12,8,8%, 14,5% -15,2% and 0,56-0,62% respectively. Digestibility rate of the dietary dry matters, lipid and protein phosphorus were varied from 50-62%, 93%-96%, 79-84% and 66-76 % respectively. The dietary factors did not produce a significant effect on the organ indexes, body chemical composition, digestibility ratios of diets in the fish (P>0.05). In the experiment Feed*Fitaz interaction was found to be insignificant. However, the difference between the total nitrogen (N), particulate nitrogen (N), particulate phosphorus (P) and total solid discharge values is insignificant in all experimental groups, while the total phosphorus, dissolved phosphorus and dissolved nitrogen discharge values differences were found significant (P <0.05). In addition, the total phosphorus, dissolved phosphorus and dissolved nitrogen discharge amounts were increased in all the groups fed with experimental diets containing phytase enzyme but the amount of phosphorus discharge was decreased (P <0,05).In trial group fishes, values of total nitrogen and phosphorus consumption, gain and retention were calculated as 1139-1173 mg/kg versus 248-279 mg/kg, 315-350 mg/kg versus 73-82 mg/kg, 27,2-30,6% versus 26-33%, based on the average daily weight. In all the calculations relating to trials, the interaction between dietary protein source and phytase factors were found to be statistically non-significant. The use of the phytase enzyme in the experiment diets increased the amount of dissolved nitrogen, total phosphorus and dissolved phosphorus discharge, the amount of dissolved phosphorus released from all the experimental groups due to the decrease in the amount of use of the hazelnuts meal and soybeans meal in diets or the increase in the amount of fish meal, but also increased phosphorus levels in all groups fed with diets containing the phytase enzyme (P<0,05).