Short communication: Comparison of hemato-immunological parameters in rainbow trout (Oncorhynchus mykiss): Palomino vs naturally pigmented varieties

Aim of the study: To evaluate hemato-immunological parameters in the Palomino trout compared to naturally pigmented rainbow trout. Area of study: Fars province (SW Iran). Material and methods: Sixty fish of both varieties (30 Palomino and 30 naturally pigmented) were sampled from the same pond. After blood sampling, hematological parameters, total serum protein and immunoglobulin (Ig), phagocytic activity, respiratory burst activity, serum lysozyme, and bactericidal activity were measured. Main results: Number of white blood cells, total protein, total immunoglobulins, lysozyme, and bactericidal activities in serum of Palomino trout were significantly higher than those in naturally pigmented rainbow trout. However, no significant changes were observed in no. of red blood cells, hemoglobin, hematocrit, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, differential leukocyte count, phagocytic, and respiratory burst activity. Research highlights: The immune system performance of Palomino trout was similar to naturally pigmented fish. However, in some cases, the immune response of Palomino fish may be even more robust than that of naturally pigmented fish. This finding helps us to favor Palomino trout in breeding programs and genetic modification.