Non-specific immune responses, stress resistance and growth performance of Caspian roach (Rutilus caspicus) fed diet supplemented with earthworm (Eisenia foetida) extract

This study was conducted to evaluate the amino acid profile of earthworm (Eisenia foetida) extract (EFE) and its dietary effects on serum immune parameters, resistance to salinity stress and growth performance of Caspian roach fingerling (Rutilus caspicus) in a feeding experiment. Three triplicated treatments (two levels of dietary earthworm extracts diluted with distilled water includes 1:25 [T1] and 1:50 [T2] and one diet with no extract distilled water as a control diet) were prepared and fed to fingerlings)4.30 ± 0.10 g) stocked in nine 100 L tanks. The amino acid profile analysis demonstrated presence of 16 amino acids (Aspartic acid, Glutamic acid, Serine, Histidine, Glycine, Threonine, Arginine, Tryptophan, Alanine, Tyrosine, Methionine, Valine, Phenylalanine, Isoleucine, leucine and lysine) in the earthworm extract. Additionally, at the end of 8-week feeding trial, fish fed E. foetida extracts showed notably higher serum total Ig and lysozyme activity (P < .05). Additionally, serum ACH50 activity improved significantly in E. foetida diluted extract (1:25 V/V) fed treatment (P < .05). For salinity challenge test, the results revealed that dietary administration of EFE (regardless of inclusion level) significantly increased fish resistance compared to control group (P < .05). For growth performance, results revealed that EFE significantly improved weight gain and specific growth rate, food palatability index and feed conversion ratio compared to the control group (P < .05). These findings revealed positive effects of EFE in Caspian roach fingerling diets and their applying in Caspian roach fingerling culture. Additionally, fish fed with E. foetida diluted extract (1:25 V/V) exhibited the best results.