• Lactoferrin;
  • growth;
  • haematology;
  • non-specific immune;
  • rainbow trout Oncorhynchus mykiss (Walbaum)


The aim of this study was to investigate the effect of dietary lactoferrin (Lf) on growth, haematology and non-specific immune response of rainbow trout Oncorhynchus mykiss (Walbaum). Fish were fed an experimental diet containing 0 (as control), 50, 100, 200 and 400 mg Lf kg−1 diet twice daily for 8 weeks and sampled at 2, 4, 6 (immune function and growth), and 8 weeks (immune function, haematology and growth). Statistical analyses revealed no significant effects of dietary Lf on growth performance (specific growth rate, weight gain, feed conversion ratio, feed intake and condition factor) or haematological parameters (red and white blood cell count, haemoglobin, haematocrit, serum iron and total iron binding capacity [TIBC]). Among the serum non-specific immune parameters, lysozyme activity increased significantly in fish fed 100, 200, or 400 mg Lf kg−1 feed for 8 weeks, whereas haemolytic complement activity increased in fish fed 100 and 400 mg Lf kg−1 diet after 6 weeks. The antiprotease activity increased in groups fed 100, 200 or 400 mg Lf kg−1 diet after 8 weeks. However, no significant effect was observed on serum peroxidase level. It can be concluded that feeding of rainbow trout on the diet supplemented with 100 mg kg−1 or higher for 8 weeks enhances the non-specific immune response.