Effects of dietary fish oil replacement by canola oil on some functional and growth parameters in juveniles of Salmo caspius

This study aimed demonstrating the effects of  total and 50% dietary fish oil  replacement by canola oil on growth performance, carcass analysis, some blood parameters and serology in 135 juvenile Caspian Sea Salmon (Salmo trutta caspius) (4.25 ± 0.68 g) for 60 days. Triplicate groups of 15 fish in 9 fiber glass tank held under identical culture conditions (14.7 ± 1.5 ° C, aerated, dissolved oxygen was 7.6 ± 0.86 mg / l, 12-h light/12-h dark photoperiod) were fed three times daily. Three diets were formulated to replace dietaary fish oil containing the same protein level 43% and fat levels of 14% by canola oil (100% fish oil, 100% canola oil and 50% fish oil with 50% canola oil). Fish fed with 50% fish oil and 50% canola oil diets had significant differences on growth performance with other treatments (P<0.05). FeeThis study aim was demonstrating the effects of total and 50% dietary fish oil replacement by canola oil on growth performance, carcass analysis, blood parameters and serology in juvenile Caspian brown trout (Salmo caspius, 4.25±0.68 g) for 60 days. Triplicate groups of 15 fish in nine fiberglass tanks held under identical culture conditions (temperature, aerated, dissolved oxygen and photoperiod) were fed three times a day. Three diets were formulated to replace the dietary fish oil containing the same protein level 43% and fat levels of 14% by canola oil (100% fish oil, 100% canola oil and 50% fish oil 50% canola oil). Fish fed with 50% fish oil and 50% canola oil diets had significantly different growth performance compared with other treatments (p<0.05). Feed conversion ratio was significantly different in all treatments with the highest FCR value in 100% fish oil treatment (p<0.05). There was no significant difference on survival rate, carcass protein, fat and moisture. Levels of liver enzymes (Lactate dehydrogenase and Alanine aminotransferase, alkaline phosphatase, aspartate aminotransferase) were significantly higher in 100% fish oil than other treatments. Canola oil improved the immune system and enzymes including ALP, AST, ALT and LDH. Based on the obtained results it can be inferred that replacing 50% fish oil with 50% canola oil in the diet was a suitable for Caspian brown trout which not only had positive effects on growth indices but also can reduce feed formulation costs.d conversion ratio, was significant difference in all treatments and the highest amount was observed in 100% fish oil treatment (P<0.05). There was no significant differences on survival rate, protein, fat and carcass moisture content. The levels of liver enzymes (LDH and ALT, ALP, AST) were significantly higher in 100% fish oil than other treatments. The amount of liver enzymes in treatments containing canola oil was less than treatment with fish oil. Canola oil improved the immune system and enzymes. The result showed that replaced 50% fish oil with 50% canola oil in the diet was a suitable dietary lipid source for Caspian Sea salmon and the  positive effect on growth indices and it can reduce costs by reducing the length of the breeding season.