Effects of supplementing diet with the alcoholic and nanoencapsulated nettle (Urtica dioica) extracts on growth performance and hematological indices of rainbow trout (Oncorhynchus mykiss)

This study was carried out to evaluate the effects of alcoholic and nanoencapsulated nettle (Urtica dioica) extracts on growth performance and hematological indices of rainbow trout (Oncorhynchus mykiss). A total of 225 rainbow trout with an average initial weight of 23 ± 0.16 g (mean ± standard deviation) were fed with five diets supplemented with 0% (control group), 1% alcoholic extract (A1), 2% alcoholic extract (A2), 1% nanoparticle extract (N1) and 2% nanoparticle extract (N2) for 8 weeks. The treatments A2 and N2 showed significantly higher final weight and specific growth rate compared to the control as well as A1 and N1. The experimental diets exhibited significant effects on some hematological indices, such that the highest levels of white blood cells, lymphocytes, total protein, albumin and also lysozyme activity were observed in A2 and N2. These results suggested that supplementing diet with the alcoholic and nanoencapsulated nettle extracts enhance immunity, and promote fish growth.