Effect of Tilia tomentosa methanolic extract on growth performance, digestive enzyme activity, immune response and haematological indices of common carp (Cyprinus carpio)

Abstract

This study was conducted to determine the effect of dietary supplementation with Tilia tomentosa on the growth performance, digestive enzyme activity, haematological indices and nonspecific immune indices of juvenile common carp (Cyprinus carpio). Fish with an average weight of 4.35 ± 0.16 g were fed a diet supplemented with an aqueous methanolic extract of T. tomentosa at a dose of 0% (control), 0.01%, 0.05% or 0.1% over 45 days. By the end of the study, the final weight, weight gain and specific growth rate were observed to be significantly higher for the 00.1% and 0.1% groups compared with the control group (P < 0.05). The feed conversion ratio was significantly decreased in the 0.05% and 0.1% groups compared with the control (P < 0.05). The activities of various digestive enzymes (amylase, lipase and trypsin) were also measured and no significant differences were observed compared to the control (P > 0.05). The mean cell volume of the 0.01% group was significantly increased compared to the control (P < 0.05) and increased lysozyme activity was observed in the 0.05% and 0.1% groups. Respiratory burst activity was significantly increased (P < 0.05) on days 15 and 30 for the 0.1% and 0.05% groups, respectively. No differences were observed for myeloperoxidase activity among the four groups. These results suggest that aqueous methanolic extract of T. tomentosa has a growth-promoting and immunostimulatory effect on common carp.