Effect of wood betony (Stachys lavandulifolia Vahl) extract on some serum biochemical changes and acute stress response in juvenile common carp (Cyprinus carpio)

The effects of four different levels of wood betony (WB) (Stachys lavandulifolia Vahl) extract (0, 2, 4 and 8% W/W in the diet) were investigated on some serum enzymatic activities and acute stress response of juvenile common carp (Cyprinus carpio). After 10 weeks post feeding, two groups of fish (0 and 8% WB) were subjected to handling and crowding stress and the stress responses including serum cortisol, glucose and some electrolytes (Na+, K+ and Ca+2) levels were assayed. The results revealed that the fish fed on 8% WB had significantly lower levels of lactate dehydrogenase (LDH) and alanine transaminase (ALT) compared to the control group (P<0.05). Although cortisol and glucose levels were increased significantly shortly after stress (P<0.05), the elevation level was significantly lower for fish fed on 8% WB (P < 0.05). In control group, sodium level decreased (P < 0.05) at 3 h post stress but did not show any change in 8% WB (P > 0.05). The potassium and calcium levels showed insignificant fluctuations post stress (P>0.05). Dietary inclusion of WB seems to improve liver function and response to acute stress in juvenile common carp.