Effects Of Different Algal Diets On The Growth,Immunity,Digestion And Nutrient Composition Of The Sea Cucumber Apostichopus Japonicus

Sea cucumber(Apostichopus japonicus)is an important economic aquatic seafood in China,which is considered to be a delicacy with both high nutritional and medicinal value,and also widely welcomed by the people over the nation,its huge market demand also promote the development of the related aquaculture industry and economic technology development.As we all know,the fodder industry is the basis and guarantee for the culture and production of the A.japonicus,especially under the trend of rising market demand,expanding culture scale,increasing cost and decreasing supplyment of traditional feedstuffs today.Therefore,searching for the substitute of traditional algae to solve the resource shortage of the traditional algae feed and provid adequate nutrition for healthy growth of A.japonicus has become to another topic for the development of the A.japonicus algae feed exploitation.This study is aim to quest the influence of different algal fodder on plankton;juvenile and young A.japonicus mainly produced in Shandong and Liaoning Peninsula,according to its growth performance;immune function;digestibility;body parietal nutrient composition respectively.To explore the palatability and cultivation effect of different algal fodder on A.japonicus at each individual developmental stages,in order to screen out the new ideal algal materials substitute for traditional algae feed,thus to alleviate the shortage of traditional raw feed such as Sargassum thunbergii and Sargassum miyabei,help the recovery of these resources,economize the fodder cost and reduce the negative effect of A.japonicus culture industry to the environment.This study also provides basic information for the immune;digestion and feed nutrition research of A.japonicus.The main results of the study are as follows:1)This study investigated the growth and development;survival rate;composition of amino acid;immune and digestive enzyme of five A.japonicus planktonic larvae groups feed with Chaetoceros muelleri;Dunaliella salina;Isochrysis galbana;Rhodomonas sp.powder and the admixture of four kinds of larval bait respectively.The results showed that there is no significant difference in body length and width between the Chaetoceros muelleri algae feed group and the mixed diet group(P>0.05)during the senior auricularia stage,the larval body width of the Isochrysis galbana feed group was significantly higher than that of other groups(P<0.05),and the difference of body length between Isochrysis galbana feed group and Dunaliella salina feed group was not significant(P>0.05).From the seventh days to the end of the experiment,the survival rate of the Dunaliella salina feed group was significantly higher than that of the Isochrysis galbana feed group,and the difference was not significant to the Chaetoceros muelleri feed group and the mixed diet group(P>0.05).The survival rate of larvae feed with Rhodomonas sp.powder reduced to 0% at the eighth experimental day which seems the Rhodomonas sp.powder is not able to support the A.japonicus larvae alone.The activity of lipase and amylase in the lavrae feed with Dunaliella salina was significantly higher than that in other groups(P<0.05),the activity of pepsin in the lavrae feed with Rhodomonas sp.powder was significantly higher than that in other groups(P<0.05)and the Chaetoceros muelleri diet group showed the highest amylase activity(P<0.05).Amino acids,including glutamic acid,aspartic acid and lysine,were the most abundant amino acids in the larvae according to the test.The total amino acid contented in the Dunaliella salina feed group was 249.78±8.07mg/g,higher than that in other groups.A small amount of taurine was detected in the larval samples of each group,but no such amino acid was detected in all larval diet samples.Few cysteine acid had been found in the Chaetoceros muelleri and the larvae of gastrula stage,but not been detected in the remaining samples.2)This study was mainly to explore the growth performance,survival rate,digestive tract traits index,immune enzyme,digestive enzyme,Body parietal nutrient composition and the ammonia nitrogen in aquatic water of six juvenile A.japonicus groups in average weight of 35 mg feed with Ulva lactuca;Enteromorpha prolifera and 4 kinds of Sargassum sp.produced in China,Vietnam,India and Philippines,mixture with compound feed and marine mud respectively.The results showed that there was no significant difference in terminal body mass between the domestic Sargassum group and the Sargassum Philippines sp.group(P>0.05),which was significantly higher than that of Ulva lactuca and Enteromorpha prolifera group(P<0.05).The visceral wall ratio of Ulva lactuca and Enteromorpha prolifera group was comparely low,which is only 10.22% and 12.42%,may probably because of the comparely high protein content of these two kind of algae.The intestinal pepsin activity in Enteromorpha prolifera group was significantly higher than that of other groups(P<0.05).The activity of cellulase in the intestinal tract of Sargassum Philippines sp.group was significantly higher than that of other groups(P<0.05).The activity of intestinal lipase and amylase in the juvenile A.japonicus of Ulva lactuca group was significant high(P<0.05).The body wall crude protein content of Sargassum Vietnam sp.was the highest: 35.56%,and the crude protein content of the Ulva lactuca and Sargassum Indonesia sp.group was significantly lower than that of the other groups(P<0.05).The difference between the water content of the body wall over the six experimental groups was not significant(P>0.05).The average content of taurine in the body wall of the juvenile A.japonicus was comparely low,only about 20mg/g,and the total amino acid content of the body wall was relatively high in the domestic Sargassum and Enteromorpha prolifera group,which was significantly higher than that of Sargassum Indonesia sp.group(P<0.05).The content of ammonia nitrogen in the aquatic water of the 3 species of import Sargassum were comparely low and the difference between each other was not significant(P>0.05),followed by the domestic Sargassum and Ulva lactuca group,0.67 and 0.79 mg per liter respectively,the difference between these two groups was not significant(P>0.05).The aquatic water ammonia nitrogen content of Enteromorpha prolifera group is the highest,which is 1.13 mg/L,and the difference is significant(P<0.05).3)The purpose of this study was to investigate the growth performance,survival rate,digestive tract traits index,immune enzyme,digestive enzyme,Body parietal nutrient composition and the ammonia nitrogen in aquatic water of six young A.japonicus groups in average weight of 1±0.2g feed with Ulva lactuca;Enteromorpha prolifera and 4 kinds of Sargassum sp.produced in China,Vietnam,India and Philippines,mixture with compound feed and marine mud respectively.The results showed that The final body mass of the domestic Sargassum group A.japonicus was higher than that of other groups,followed by the Sargassum Vietnam sp.Group,the Enteromorpha prolifera and Ulva lactuca group were lower then that of other groups,the difference between these two groups was not significant(P>0.05),and the body mass of the Enteromorpha prolifera group were significantly lower then the highest two groups(P<0.05).The growth rate of domestic Sargassum fed A.japonicus was 218.22%,which is higher than that of other groups and the lowest group was Enteromorpha prolifera feed A.japonicus,only about 120.49%,the difference is significant(P<0.05).Which is similar to the juvenile A.japonicus,the visceral wall ratio of Ulva lactuca and Enteromorpha prolifera group was comparely low,only about 11.94% and 11.29% respectively.The body wall crude fat content of Sargassum Vietnam sp.group was 9.59%,which was significantly higher than that of the other groups(P<0.05),and the difference in the body wall protein and water content of the young A.japonicus between each group was not significant(P>0.05).Similar to the juvenile A.japonicus,the content of glutamic;glycine;aspartic and arginine acid were found to be more abundant in the body wall of the young A.japonicus,and the lowest content amino acids was detected to be taurine,only about 0.25-0.43mg/g.The total amino acid content of Sargassum Vietnam sp.group was higher then that of other groups,and the lowest group was the Sargassum Philippines sp.fed A.japonicus,these two groups were significantly different to each other(P<0.05)and not different from the other groups significantly(P>0.05).The ammonia nitrogen content in the aquatic water was similar to that of the juvenile A.japonicus.The highest content group was Ulva lactuca and Enteromorpha prolifera fed A.japonicus,0.76mg/L and 0.98mg/L respectively,and the difference was significant(P<0.05).