Effects of lysophospholipid on growth performance, hematological indices, hepatic enzymes and lysozyme activity in rainbow trout (Onchorhyncus mykiss) diet containing fat powder

In the present study we investigated the effects of lysophospholipid (LPL) different levels on growth, hematological indices, hepatic enzymes and lysozyme activity in rainbow trout fed diets containing fat powder. Experimental diets were four different levels including 0, 3, 6 and 9 gkg-1 LPL and control diet (containing fish oil) each in triplicate. After 56 days of trial, measuring growth parameter suggested improvement of body weight increasing, specific growth rate and feed conversion ratio in LPL 9 compare to other diets containing fat powder, however, control diet owned the highest value (P<0.05). Also, inclusion of LPL caused an increasing in conditional factor of fish fed fat powder diets (P<0.05). According to the hematological indices, white blood cell highest value was observed in diets containing fat powder (P<0.05), while, red blood cell increased significantly by addition of 6 and 9 gkg-1 LPL to fat powder (P<0.05). Furthermore, administration of control and LPL 9 resulted in hematocrit enhancement among experimental diets (P<0.05). Enzyme evaluation revealed lower lysozyme activity in fat powder diets supplemented with 0 and 3 gkg-1 LPL compared other diets (P<0.05). Contrarily, hepatic enzymes elevated in fish fed fat powder diets (P<0.05). However, administration of 9 gkg-1 LPL led to decrease this value (P<0.05). Considering the results of the present study supplementation of 9 g LPL is suggested in rainbow trout diet containing ≈70% fat powder.