Effects Of Ca²⁺ And Dietary Fat Stress On Energy Metabolism And Premature Of Eriocheir Sinensis

This study investigated the following aspects, including difference on energy budget between preconcious and normal Chinese mitten crab; effects of aqueous Ca²⁺ concentration (18mg/L, 40mg/L, 80mg/L, 120mg/L and 160mg/L) on energy budget and precociousness of Chinese mitten crabs; and dietary fat concentration (3%, 6%, 9% and 12%) on energy budget and precociousness of Chinese mitten crabs. The following conclusions were reached: Part one: Comparison of the energy budget, hepatopancreas index (HPI) and gonads index (GSI) between precocious and normal crabs.There was significant difference between precocious and normal crabs, growth rate and growth energy percentage in precocious crabs were significantly lower than that in normal crabs (P<0.05). Precocious crabs HPI was significantly lower than normal crabs (P<0.05), but GSI was significantly higher than normal crabs (P<0.05). There was no significant difference between precocious and normal crab in AKP activities in hepatopancreas (P>0.05), while there was significant difference between preconscious and normal crab in AKP activities in gonads (P<0.05). Energy charge in hepatopancreas in precocious crabs was significantly lower than that in normal crabs, and it suggested that metabolism rate in precocious crabs was significantly lower than that in normal crabs.Part two: Effects of aqueous Ca²⁺ concentration on energy budget and precociousness of Chinese mitten crabsThe SGR and K first increased and then decreased with increasing aqueous Ca²⁺ concentration. Demarcation point was at aqueous Ca²⁺ concentration 40mg/L. So the energy allocated to growth, the crabs at aqueous Ca²⁺ concentration 40mg/L were significantly higher than the crabs at aqueous Ca²⁺ concentration 18mg/L, but the former was not significantly higher than the crabs at other aqueous Ca²⁺ concentration. The HIS decreased with increasing aqueous Ca²⁺ concentration, HIS at aqueous Ca²⁺ concentration 18mg/L was significantly higher than that at aqueous Ca²⁺ concentration 160mg/L; The GSI increased with increasing aqueous Ca²⁺ concentration, GSI at aqueous Ca²⁺ concentration 18mg/L was significantly lower than that at aqueous Ca²⁺ concentration 160mg/L. aqueous Ca²⁺ urged nutrients cosumption and gonad development. The activities of AKP in hepatopancreas decreased insignificantly and the activities of AKP in gonads increased significantly with increasing aqueous Ca²⁺ concentration. The energy charge in hepatopancreas was highest at aqueous Ca²⁺ concentration 40mg/L, the cells were active; metabolism was vigorously; and growth was best. These results showed that the effects of aqueous Ca²⁺ on Chinese mitten crabs was mainly attributed to nutritive material consumption.Part three: Effects of dietary fat concentration on energy budget and precociousness of Chinese mitten crabsSGR and K showed the effects of dietary fat on Chinese mitten crabs. The energy allocated to growth first increaseed and then decreaseed with the increasing dietary fat concentration, and that was the highest at dietary fat concentration 9%, significantly higher than others. The HIS decreased with increasing dietary fat concentration, HIS at dietary fat concentration 12% was significantly lower than others. The GSI increased with increasing dietary fat concentration, GSI was the lowest at dietary fat concentration 3%, significantly lower than others; GSI was the highest at dietary fat concentration 12%, significantly higher than others. The activities of AKP in hepatopancreas increased insignificantly and the activities of AKP in gonads increased significantly with increasing dietary fat concentration. The energy charge in hepatopancreas was highest at dietary fat concentration 9%, the cells were active; metabolism was vigorously; and growth was best.Ca²⁺ and dietary fat are just like a double-edged sword, both of them will urge the growth of Chinese mitten crabs, every physiological exponent is the best, if the concentration is the appropriate; They will urge gonad development, lead to premature, inhibit the growth, if the concentration is too high.To harvest most in practice for the Chinese mitten crab culture, Culturists must pay attention to alterative water quality, prevent high aqueous Ca²⁺ concentration, in case of inhabiting growth; they must make reasonable ratio of nutritive material, it make the growth best.