Effects of white mustard (Sinapis alba) and flax seed (Linum usitatissimum) oils on growth performance, immune response, blood parameters, digestive enzymes and antioxidant enzyme activities of rainbow trout (Oncorhynchus mykiss)

This study evaluated effects of dietary supplementation of White Mustard (Sinapis alba) and Flax Seed (Linum usitatissimum) oils on Growth Performance Parameters, Immunology Parameters, disease resistance, Hematological Parameters, Digestive Enzyme Activities, and Antioxidant Enzyme Activities in rainbow trout (Oncorhynchus mykiss) juveniles. For this purpose, 735 rainbow trout with an initial body weight of 25.77±0.13g divided into seven main groups with triplicates per group and 35 fish per tank. Fish were fed daily ad libitum with diets containing White Mustard and Flax Seed at 0.5, 1and 1, 5 for 63 days. The results showed that growth performance (FW, WG, SGR) in all groups were increased significantly (P<0.05). There were no significant difference (P > 0.05) about feed conversion ratio (FCR) in treatment groups that fed diets containing various levels of seeds oils. NBT and PK activity were lower than control at the end of the experiment (P <0, 05), LYS and MPO values were higher in all experimental groups than the control group (P <0, 05) at the end of the experiment (P <0, 05). Cytokine gene expressions in Kidney and intestine were elevated in all experimental groups compared to that of control (P < 0.05), except IL-B, IL-8, IL-10, INOS expression in the spleen at 63rd day sampling time. Other sampling times, the immune-related genes were also elevated in all experimental groups compared to that of the control group. According to the results, when the erythrocyte, hemoglobin, hematocrit, mean corpuscular volume, main corpuscular hemoglobin, main corpuscular hemoglobin concentration were investigated, there was no significant difference between the control group and the experimental groups (p> 0.05). Pepsin and trypsin decreased in all experimental groups, whereas amylase activity not affected. While lipase increased in all experimental groups, but all these changes were not significant. In terms of antioxidant enzyme activities, significant improvement in liver SOD, CAT and, GST activities in all treatment groups (P< 0.05). In addition, a significant declined in liver LPO level in all treated groups and in all sampling times compared to the control (P> 0.05). At the end of this experiment, the results of the challenge test against Yersinia ruckeri showed that administration of seeds oils supplemented diets significantly increased trout resistance (P < 0.05); the highest survival rate, was observed in the AKH 1% group. While no significant difference (P > 0.05) against Aeromonas hydrophila.in all oils groups. As a result, in terms of growth parameters, immunology parameters, disease resistance against Y. rukari, and antioxidant enzymes, these oils generally have an advantage, while the positive effects of the fish on their digestive enzymes and hematological parameters are often lacking.