Effects of chronic ammonia nitrogen stress on growth,survival and energy metabolism of Macrobrachium rosenbergii

【Objective】To elucidate the effects of chronic ammonia nitrogen stress on the growth,survival and energy metabolism of Macrobrachium rosenbergi and its adaptive mechanism,it provided theoretical basis for healthy breeding of M. rosenbergii. 【Method】In this study,through 48 d cultivation experiment in the cultivation workshop,six different ammonia nitrogen concentrations were set:0.02 mg/L(control),0.50 mg/L(T0.50),1.04 mg/L(T1.04),2.14 mg/L(T2.14),4.42 mg/L(T4.42) and 9.03 mg/L(T9.03). The effects of chronic ammonia nitrogen stress on feeding,growth,survival,serum energy-supplying substances contents and enzymes related to energy metabolism of M. rosenbergii were studied.【Result】The results showed that the survival rate of T9.03 group was significantly lower than that of the control group(P<0.05,the same below),and there was no significant difference between survival rates of other stress groups and the control group(P>0.05,the same below). The feeding rate,feed efficiency,weight gain rate,relative growth rate and specific growth rate all showed a decreasing trend with the increase of ammonia nitrogen concentration,and the feed coefficient and weight difference coefficient showed an increasing trend with the increase of ammonia nitrogen concentration. Serum glucose(Glu) content increased first and then decreased with the duration of ammonia nitrogen stress. The contents of serum triglyceride(TG) and total cholesterol(T-CHO) decreased with the increase of ammonia concentration after 12 d of stress. There was no significant difference in serum total protein(TP) content between stress groups and the control group before 24 d of stress,but on day 48,TP content showed a decreasing trend with the increase of ammonia concentration in stress groups,moreover,except for the T0.50 group,all other stress groups were significantly lower than the control group.Serum lactic acid(LA) content showed an increasing trend with the increase of ammonia nitrogen concentration. In addition,the activities of hexokinase(HK),pyruvate kinase(PK) and lactate dehydrogenase(LDH) in the stress groups were increased first and then decreased later with the extension of the stress time; phosphoenolpyruvate carboxylase(PEPCK) activity was significantly higher in the stress group than in the control group during 12-48 d of experiment. The activity of succinate dehydrogenase(SDH) decreased with the increase of ammonia nitrogen concentration,and the activity of T4.42and T9.03 groups was significantly lower than that of the control group. 【Conclusion】The maximum concentration of ammonia nitrogen on M. rosenbergii was 0.50 mg/L. In order to cope with the chronic long-term high concentration of ammonia nitrogen stress,the energy supply and utilization route of M. rosenbergii changes significantly,which finally significantly affects its feeding,growth and survival,resulting in poor breeding effect. In intensive production,attention should be paid to the ammonia nitrogen content in aquaculture water to reduce the additional high energy consumption caused by ammonia nitrogen and improve the production efficiency.