The dietary wood betony, Stachys lavandulifolia Vahl extract as a growth promoter and immune enhancer in common carp (Cyprinus carpio).

The present study was conducted to evaluate the efficacy of wood betony (WB), Stachys lavandulifolia extract on growth performance and some immune responses in common carp, Cyprinus carpio. Different concentrations of the WB extract 0, 2, 4 and 8% (g per 100 g of diet) were added to commercial diet. Each treatment was randomly assigned to triplicate groups of fish having average initial weight of 44 ± 0.62 g for 10 weeks. The results showed that final weight, food conversion ratio, specific growth rate and condition factor were significantly improved by WB in a dose dependent manner, where the best growth parameters were achieved in the group of fish receiving the highest concentration of WB (P<0.05). Feeding fish at 2 and 4% W/W by WB in the diet improved lysozyme activity, ACH50 and IgM levels significantly in comparison to the control (P<0.05). Group of fish fed on 4% WB in the diet had the best levels of the immune characteristics (P<0.05). Based on the results of this study, it is recommended to feed common carp with WB to improve growth and non-specific immunity.