Comparative study on albino and pigmented rainbow trout (Oncorhynchus mykiss): growth, non-specific immunity, disease resistance, and related gene expressions

Studies are showing that albinism has negative effects on growth and immunity in rainbow trout, and there are also studies showing the opposite. Therefore, in this study, a comparison has been made between the albino (AA), normal pigmented (PP), mixtures (Mix), and their crossbreds (AP and PA) of rainbow trout in terms of growth performance, non-specific immune system parameters, mRNA relative expression levels, and disease resistance. Regarding the non-specific immune system parameters examined, the albino group (AA) showed the highest lysozyme, NBT, and IgM levels, while the normal pigmented (PP) group exhibited the lowest values. The lowest mortality rate was observed after the challenge test in the AA group (16%), followed by PA (30.66%), Mix (32.00%), and AP (36.00%), with the highest mortality rate recorded in the PP group (52.00%). The results obtained from experimental research have been confirmed through molecular analyses. The expression level of IL-8 showed the highest level in the AA group (6.05 ± 1.95^a), followed by PA (4.44 ± 1.60^ab), Mix (3.04 ± 0.72^bc), and AP (1.29 ± 0.23^c) groups compared to the PP group (onefold). There was no statistical difference among the groups regarding growth performance (except for specific growth rates and final weights) and IGF-1 mRNA expression levels. In conclusion, the study suggests that albinism does not have a detrimental effect on rainbow trout. In addition, the observation of a strong non-specific immune system in albinism could promote more efficient and sustainable aquaculture.