| Litopenaeus vannamei is one of the most popular shellfish products around the world due to its delicate,elastic texture and high nutritional value.However,in some countries like China,the distances between coastal areas and inland areas are very long,and as a result,it is difficult and expensive to maintain the quality of aquatic products during long-distance transport with water.Therefore,it is essential to study technologies that can maintain a high survival rate in water-free conditions.This study simulated the water-free transport of L.vannamei.The shrimp were immersed in a life-sustaining formula at 13 ℃ for 3 minutes until all of them fell into a comatose state.They were then placed in sealed bags filled with oxygen and transported in an under 15 ℃ environment.After 10 hours,the shrimp were transferred into water and were left to recover.This study investigated the effectiveness of different life-sustaining formulas that kept the shrimp alive during transport and their effects on the physiological and biochemical indexes of shrimp before and after transport and their effects on the shrimp’s muscles and gills.The main findings are as follows:1.The experiment confirmed that the application of a 1:1 loach to water mix can improve the survival rate of shrimps in water-free transport.Through documenting the data of serum,hemocyanin,lactic acid,reactive oxygen species(ROS),total anti-oxidant capability(T-AOC),malondialdehyde(MDA),superoxide dismutase(SOD),alanine transaminase(ALT)and aspartate aminotransferase(AST)between the loach slime group and the control group,the experiment studied the effects of loach slime on mitigating the stress response of shrimp during water-free transport conditions.The results show that L.vannamei had an 84.4% survival rate(compared to the 66.7% survival rate of the control group)under the effect of loach slime after a10-hour water-free transport.Compared to the control group,serum hemocyanin and lactic acid concentrations of shrimps in loach slime group increased during transport;there was less accumulation of ROS,MDA,AST,ALT and higher concentrations of SOD and T-AOC in the shrimp from the loach slime group and.The changes mentioned above show that L.vannamei,under the effect of the loach slime,have higher respiratory metabolic intensity and lower oxidative stress response due to adverse conditions during transport;a small impact on the structure and function of the organization and the body is more adaptive to stress.The control group had lower SOD and T-AOC concentration,higher ROS and MDA concentration,and intenser oxidation reaction and lipid peroxidation.Damaged cell membrane structure led to increased AST and ALT outflow,which affected basic functions including breathing and caused higher death rates.2.The experiment confirmed that the application of 3.5% sorbitol solution can also improve the survival rate.Through documenting the data of serum hemocyanin,lactic acid,glucose,liver glycogen content,SOD,lactate dehydrogenase(LDH),succinate dehydrogenase(SDH)between sorbitol group and control group,the experiment studied the effects of sorbitol on respiration and capacity metabolism of shrimps under water-free transport conditions.Under the effect of sorbitol group,L.vannamei had a 88.8% survival rate(compared to the 70.0% survival rate of the control group)after a 10-hour water-free transport).Compared to the control group,hemocyanin,lactic acid,T-AOC,SDH,LDH,and SOD concentrations were higher in the sorbitol group;blood glucose concentrations were more stable but liver glycogen consumption was greater.The sorbitol-coated shrimp had higher respiration and energy metabolism,less metabolic disturbance and bodily damage,higher ability to cope with stressful conditions such as water-free and low-temperature transport,and improved survival rate of L.vannamei in water-free transport.The vitality of SDH of the control group recovered slowly after being put back into a water environment,their vitality of LDH remained relatively low throughout the transport.This finding indicates that the restrained respiratory metabolism and disturbance of intracellular ion metabolism are a few of the reasons leading to high death rate in the control group.3.Through documenting the data of adenylic nucleotides(ATP,ADP,AMP,IMP)contents,adenylic energy charge(AEC),p H,water-holding capacity,muscle springiness,cohesiveness,gumminess,chewiness and histological,ultrastructure changes of gills between sorbitol group and control group,the experiment studied how water-free transport and life-sustaining formula changed the properties of shrimps’ muscles and structure of its gill.As a result,after transport,the muscle ATP concentration and AEC of L.vannamei decreased,the ADP,AMP,and IMP concentration increased,and the textural properties of the muscles and their water-holding capacity deteriorated.The transport improved the flavor of the shrimp but the textural feel worsened.After recovering,the muscle nucleotide content of the shrimp in the sorbitol group recovered quicker which indicated that the energy metabolism was higher than that in the control group.However,the textural properties and water-holding capacity of the two groups did not recover.Histological changes of gills during transport revealed damage in the gill epithelium,including vacuolation,broken up cuticle membrane and decreased epithelium cells.Changes of ultrastructure of gills include the gathering of lysosome,mitochondria and other organelles,altered structures of rough endoplasmic reticulum,and ruptured nuclear membranes.10hour-transport without water damaged the structure and ultrastructure of gill.There was no significant difference between the two groups.The gill damage recovered partially after being moved back to water. |
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