Effect of soybean lecithin on growth indices, body composition, digestive enzymes activities and intestinal histomorphometery of Caspian Salmon (Salmo trutta caspius)

The present study conducted to evaluate the effects of soybean lecithin on growth indices, body composition, digestive enzymes activities and intestinal histomorphometry of Caspian salmon. Ninety fish (350g ± 10) were randomly divided into three treatments with three respective replicates. The first treatment (control group) was fed with commercial feed, while the second group received diet supplemented with 12% soybean oil, and the third one received feed supplemented with 6% soybean oil and 6% soybean lecithin for 90 days. Weight gain was indicative of the statistical superiority of treatment 3 over control group and treatment 2. In addition, FCR of treatment 3 was only significantly different from control group (p≤0.05). There were significant differences regarding moisture content of treatments 2 and 3 in compare to control group (p≤0.05), however, protein and lipid contents of treatments were not significantly different (p≤0.05). Furthermore, energy contents of treatments 2 and 3 were significantly different (p≤0.05). Digestive enzymes activities (protease, lipase and amylase) of treatment 3 significantly differed from treatment 2 and control group (p≤0.05). Morphometric characteristics of intestine including epithelium thickness and external muscle thickness of treatments 2 and 3 were significantly different from those of control group (p≥0.05). In conclusion, supplementing Caspian salmon diet with 6% soybean lecithin improved growth and some physiological parameters of the fish.