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

Abstract   This study aimed demonstrating the effects of  total and ۵۰% dietary fish oil  replacement by canola oil on growth performance, carcass analysis, some blood parameters and serology in ۱۳۵ juvenile Caspian Sea Salmon (Salmo trutta caspius) (۴.۲۵ ± ۰.۶۸ g) for ۶۰ days. Triplicate groups of ۱۵ fish in ۹ fiber glass tank held under identical culture conditions (۱۴.۷ ± ۱.۵ ° C, aerated, dissolved oxygen was ۷.۶ ± ۰.۸۶ mg / l, ۱۲-h light/۱۲-h dark photoperiod) were fed three times daily. Three diets were formulated to replace dietaary fish oil containing the same protein level ۴۳% and fat levels of ۱۴% by canola oil (۱۰۰% fish oil, ۱۰۰% canola oil and ۵۰% fish oil with ۵۰% canola oil). Fish fed with ۵۰% fish oil and ۵۰% canola oil diets had significant differences on growth performance with other treatments (P<۰.۰۵). FeeThis study aim was demonstrating the effects of total and ۵۰% dietary fish oil replacement by canola oil on growth performance, carcass analysis, blood parameters and serology in juvenile Caspian brown trout (Salmo caspius, ۴.۲۵±۰.۶۸ g) for ۶۰ days. Triplicate groups of ۱۵ 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 ۴۳% and fat levels of ۱۴% by canola oil (۱۰۰% fish oil, ۱۰۰% canola oil and ۵۰% fish oil ۵۰% canola oil). Fish fed with ۵۰% fish oil and ۵۰% canola oil diets had significantly different growth performance compared with other treatments (p<۰.۰۵). Feed conversion ratio was significantly different in all treatments with the highest FCR value in ۱۰۰% fish oil treatment (p<۰.۰۵). 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 ۱۰۰% 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 ۵۰% fish oil with ۵۰% 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 ۱۰۰% fish oil treatment (P<۰.۰۵). 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 ۱۰۰% 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 ۵۰% fish oil with ۵۰% 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.    

کلیدواژه ها:

Canola oil ، Fish oil ، FCR ، Liver enzymes ، Salmo caspius ، Survival rate