Effects Of Low Salinity Stress On Growth And Meat Quality Of Macrobrachium Rosenbergii

In this paper,Macrobrachium rosenbergii was selected as the research target species.Behavior and physiology studies were used to study the effects of low salinity(0,2,4,6,8,10,12,14)conditions on the behavior,growth and development of meat of Macrobrachium rosenbergii,and to explore a viable low salinity culture and meat quality improvement methods,Make full use of fresh brackish water resources to provide a basis for selecting a salinity range suitable for the breeding of Macrobrachium rosenbergii,break the development bottleneck,increase the survival rate of Macrobrachium rosenbergii and promote the healthy development of the industry,and provide for the future development of Macrobrachium rosenbergii More useful information.the main findings are as follows:1.Effects of low salinity culture conditions on the behavior of Macrobrachium rosenbergiiBefore the start of the experiment,set up a pre-experiment with different salinity observations on its behavior to determine the behavioral actions of Macrobrachium rosenbergii.The behavioral parameters of Macrobrachium rosenbergii recorded in an hour were analyzed and plotted using SPSS20.0 software.The results showed that:(1)Salinity increased the search time of Macrobrachium rosenbergii,at 6-salt or more,the search time of Macrobrachium rosenbergii did not change much.(2)With the increase of salinity,the feeding time of Macrobrachium rosenbergii significantly changed,showing a significant decreasing trend(P<0.05).(3)The number of feedings of Macrobrachium rosenbergii tends to decrease with the increase of salinity,but when the salinity of the cultured water exceeds10,the number of feedings will be significantly affected.(4)With the increase of salinity,the exercise time of Macrobrachium rosenbergii showed a decreasing trend.Under the condition of salinity that is less than 6-salt,the impact of exercise time was relatively small.In addition,through experimental observation,it was found that under low salinity stress,the number of molting times of Macrobrachium rosenbergii was significantly lower than that of the fresh water group,and the attack frequency of the clam shells was also reduced,and the disability rate was effectively controlled,indicating that Macrobrachium rosenbergii was extracted.Therefore,by adjusting the salinity of the water body,breeding can be carried out at a lower salinity,and the survival rate of Macrobrachium rosenbergii can be improved,and the production efficiency can be improved.2.Effects of low salinity culture conditions on the growth and survival rate ofMacrobrachium rosenbergiiSeven salinity groups and one control group were set up and each group was fed with3 parallel white plastic boxes of 30 L.Each box was placed in the same size of 30 juveniles with an average mass of 5.32±0.20 g.The body length is 6.13±0.20 cm.After 45 days of low salinity cultivation,20 M.rosenbergii shrimps were randomly selected from each salinity group and the water on the surface of the shrimps was wiped dry with absorbent paper.Body weight and body length were measured and calculated.The average number of shells,growth rate of body length,growth rate of body weight,specific growth rate,fullness,and survival rate of Macrobrachium rosenbergii in each salinity group showed:(1)Length growth of Macrobrachium rosenbergii during its initial period was significantly higher than at the end of the breeding period,and the average length of growth in the initial stage of cultivation in the 0-to 6-salt salinity group was more than twice than that in the end of the cultivation.(2)The specific growth rate and plumpness of Macrobrachium rosenbergii during the initial period of culture were greater than at the end of the aquaculture period.The specific growth rates at the end of the breeding period in the 0 to6% salinity group were similar.The specific growth rate at the initial stage was significantly higher than that at the end of culture(P<0.05).(3)Within the salinity of 0~14,the survival rate of Macrobrachium rosenbergii increased with salinity,and the survival rate of Macrobrachium rosenbergii in the 0-salinity control group was the lowest with only53.82±0.453,while the survival rate of the experimental group was the highest,reaching83.36±0.795.(4)There was a phenomenon of residual food in the growth and development of Macrobrachium rosenbergii under fresh and salt water conditions,and its survival rate was related to the average number of shells.The results of this study just showed the average value of Macrobrachium rosenbergii.The smaller the number of shells,the higher the survival rate.3.Effects of low salinity culture conditions on the meat quality of Macrobrachium rosenbergiiAfter each group had been raised,they were sampled.Each group was randomly assigned to 60 pigs.Each group had 20 tails in parallel.After wiping dried shrimp body water and placing it on an ice tray,the head breastplate and hepatopancreas were immediately removed to get fresh muscles.Using a homogenizer,the muscles of shrimps were smashed and mixed,and stored at-80°C and used for the determination of amino acids and fatty acids.The results showed that:(1)During the determination of amino acids,tryptophan was destroyed during hydrolysis.The tryptophan was not detected in the muscles of Macrobrachium rosenbergii,so a total of 17 groups were detected,including two flavor amino acids,four taste amino acids,seven essential amino acids and ten non-essential amino acids;The highest content of amino acids was reached at 9.08±0.15 at a salinity of 14°C,while the content of cysteine was the lowest,only 0.17±0.16 at a salinity of 12°C;in the muscles of Macrobrachium rosenbergii,The contents of aspartic acid,tyrosine,valine,isoleucine,and lysine increased with the increase of salinity,but there was no significant difference among the salinity groups;serine,proline,and content of tyrosine,threonine and phenylalanine decreased with increasing salinity.Cysteine,histidine,methionine and leucine content did not change significantly(P> 0.05).(2)A total of 11 fatty acids were detected in each salinity group.The three fatty acid components in saturated fatty acids(SFA)were significantly different in different salinity groups(P<0.05).Among them,C14:0 decreased first and then increased with salinity increasing.The salinity was the lowest at 6(2.53±0.18);the content of three fatty acids in monounsaturated fatty acid MUFA was significantly different in different salinity groups(P<0.05),but its trend was different from that of SFA.Similarly,with the increase of salinity,it reached the highest in the salinity group at 14(30.62±0.32%);however,the polyunsaturated fatty acid(PUFA)content was not significantly different among salinity groups(P>0.05);However,the contents of the five fatty acids in PUFA have a very significant difference in different salinity groups(P<0.05),among which are C18: 2n-6,C18: 3n-3 and C20: The content of4n-6 increased with increasing salinity,and the contents of C20:5n-3(EPA)and C20: 6n-3(DHA)decreased with increasing salinity;therefore,The ratio of EPA/DHA was not significantly different in each salinity group and ranged from 1.11±0.31% to 1.18±0.48;however,the EPA+DHA content was very significant between different treatment groups(P<0.05)and decreased after an initial increase trend change in the highest 8 salinity group(14.43 ± 0.39%).Salinity changes can affect the body’s amino acid and fatty acid content,An effective regulation of the salinity of the breeding environment will improve the meat quality of Macrobrachium rosenbergii,thus improving the economic benefits of the breeding industry.