Effect of different levels of phospholipid on growth performance, fat digestibility and lipase activity in diet containing fat powder in rainbow trout (Oncorhynchus mykiss)

In the present study was evaluated the effect of dietary phospholipid on growth performance, nutrient digestibility and lipase activity in rainbow trout. Diets were prepared with 20% fat base which 60% of the experimental fat diet included fat powder. Phospholipids added in two levels (5 and 15 g/kg diet). Control diet was made without phospholipid and fat powder. 135 rainbow trout in each tank with initial mean weight of 27.45±1.88g were fed with experimental diet twice daily for 8 weeks. At the end of the experiment, growth performance, some plasma factor, nutrient digestibility and lipase activity were studied. Results of growth performance including BWI, CF, SGR, HIS, FCR demonstrated no significant differences between treatments and control group. But visceral somatic index was significantly higher in control group among treatments. Triglyceride value was significantly higher in control diet although, cholesterol didn’t have significant differences. Nutrient digestibility was significantly different among treatments. Fat and protein digestibility were higher in control and phospholipid 15, respectively and the lowest value was observed in the diet phospholipid 5. Supplemental phospholipid increased lipase activity significantly. The most value of lipase activity was observed in phospholipid 15. It seems that phospholipid provides a better growth performance due to increasing nutrient digestion and improves some parameters at level of 15g/kg in diet containing fat powder in rainbow trout.