Study On The Effect Of Phospholipids On The Optimal Lipid And Dietary Energy/protein Ratio In Juvenile Macrobrachium Nipponensis

Oriental river prawn?Macrobrachium nipponensis?is an important aquaculture crustaceans in our country.Many researches were conducted on its nutritional requirement but few on phospholipids.Phospholipids are biologically active substances that are amphiphilic and necessary for the growth and survival of shrimps.In this study,the effect of phospholipids on the requirement of lipid was explored,based on which,optimal ratio of energy to protein was determined.The research results provide important references and theoretical basis for the optimization of feed formula and breeding management of Macrobrachium nipponense.The contents and results of this study were following.1.Effect of phospholipid on lipid requirement of oriental river prawn Macrobrachium nipponensis This experiment was carried out to investigate the effects of phospholipid on the requirements of dietary lipid for oriental river prawn Macrobrachium nipponensis.The Macrobrachium nipponense with an average body weight about?0.075±0.001?g was fed in indoor tanks and fed experimental diet for 56 days.Soybean phospholipids was mixed into lipid at ratio of 33%and 67%respectively,then each mixture was supplemented into diet at 3%?6%?9%respectively?the crude lipid in diets was 7%?10%?13%respectively?to formulate six isonitrogenous and isoenergetic diets,which was named as L₃P₁,L₃P₂,L₆P₂,L₆P₄,L₉P₃,and L₉P₆ according to the supplemental amount of lipid and phospholipid.The results showed the survival rate of shirmps ranged from 47.8%to 66.8%.Among them,the survival rate of shrimp in L₆P₄ group was the highest,followed by L₃P₂ group,and the lowest in L₉P₃ group.The final body weight,weight gain rate,specific growth rate and survival rate in the high-fat group were significantly lower than those in the middle and low-fat groups?P<0.05?,and the feed coefficient was significantly higher than that in the middle and low-fat groups?P<0.05?.The final body weight,weight gain rate,specific growth rate and survival rate in the high phospholipid group were significantly higher than those in the low phospholipid group?P<0.05?,and the feed coefficient was significantly lower than that in the low phospholipid group?P<0.05?.The amount of lipid mixture and the proportion of soybean phospholipids have significant interactions with growth performance index of Macrobrachium nipponense?P<0.05?.Body lipid content increased with diet lipid level?P<0.05?,however,the crude fat content of shirmp in the high-phospholipid group was significantly lower than that in the low-phospholipid group?P<0.05?.Activities of trypsin and lipase in shrimp fed diet with high level of lipid was lower than that with middle or low level of lipid?P<0.05?;lipase activity in shrimp fed diet with high level of phospholipid was higher than that with low level of phospholipid?P<0.05?,and significant interaction was detected?P<0.05?.The activities of SOD and T-AOC in hepatopancreas of Macrobrachium nipponense were influenced by dietary lipid level?P<0.05?,the proportion of soybean phospholipids had no significant effect on them?P>0.05?.However,the addition of lipid mixture and soybean phospholipid ratio had a significant interaction with hepatopancreas T-AOC?P<0.05?.At low and high lipid levels,the phospholipid level had no significant effect on the expression of FABP10mRNA?P>0.05?.When the lipid level was middle,the expression of FABP10 mRNA was significantly higher in the high phospholipid group than in the low phospholipid group?P<0.05?.These results indicated that phospholipid should be kept in a proper proportion with total lipid in diet and it is relative optimal when diet contain 10%lipid and 4%phospholipid for the larval Macrobrachium nipponense.2.Effects of phospholipids on the intestinal flora and the transcriptome in hepatopancreas of Macrobrachium nipponense This experiment was designed to investigate the effect of phospholipids levels on the intestinal flora and transcriptome of juvenile oriental river prawn Macrobrachium nipponensis undeer different lipid conditions.The Macrobrachium nipponense with an average body weight about?0.28±0.08?g was fed in indoor tanks and fed six experimental diets for six weeks.Results showed:1.The gut microbiota of Macrobrachium nipponense was composed of bacteria belonging to the four genus of Proteobacteria,Firmicutes,Bacteroidetes and Fusobacteria.The level of phospholipids in the diet affected the intestinal flora diversity of Macrobrachium nipponense,and the microbial diversity index of the high phospholipid group was higher than the low phospholipid group.2.Using the Illumina high-throughput sequencing technology,Using Illumina high-throughput sequencing technology,6 transcriptome samples of Macrobrachium nipponense were ingested successfully.A total of 273965 Unigene sequences were obtained,among which 48994 sequences could be compared in four databases,accounting for the total Unigene 17.9%of the sequence.3.Differential gene expression analysis showed that compared to L₃P₁,L₃P₂ group had 15 genes up-regulated and 286 genes were down-regulated;compared with L₆P_2,L₆P₄ group had171 up-regulated genes and 116 down-regulated genes;compared with L₉P₃ and L₉P₆group,272 genes were up-regulated and down-regulated genes.4.Analysis of enrichment of KEGG metabolic pathways by differential genes revealed that lipid-related pathways were significantly enriched in lipids,and lipids were absorbed and synthesized in the high-phospholipid group relative to the low-phospholipid group.The related genes were significantly down-regulated?P<0.01?.In summary,the level of phospholipids indiets has a certain influence on the intestinal microflora of Macrobrachium nipponensis and the reason may be related to the regulation of linolenic acid,linoleic acid and other short-chain unsaturated fatty acids in soybean phospholipids and the phospholipid surfactants.In addition,the abundant transcriptome information obtained from Macrobrachium nipponense provided valuable data for new genes cloning,digestive physiology and genomics research.3.Study on the optimal energy-protein ratios in high phospholipid diets of Macrobrachium nipponensis The optimal dietary energy to protein?E/P?ratio in high phospholipid diets for juvenile oriental river prawn Macrobrachium nipponensis?initial average weight0.28±0.06 g?was determined using practical diets in a 3×2 factorial experiment.Three dietary protein levels?36%,40%,and 44%?and two digestible energy levels?11 MJ/kg and 12 MJ/kg?of six experimental diets were tested.Each diet was fed to juveniles in three plastic tanks?100 cm×100 cm×100 cm?for 56 days.The Results show that with the increase of feed protein levels,the survival rate?SR?,the weight gain rate?WG?and specific growth rate?SGR?and feed coefficient?FCR?of Macrobrachium nipponensis has not been found significant difference?P>0.05?,only the protein efficiency?PER?show significant difference?P<0.05?.In addition,With the improvement of the digestible energy level,the WG,SGR and PER of the Macrobrachium nipponense increased significantly?P<0.01?.There was some interaction between feed protein level and digestible energy level on the growth of Macrobrachium nipponense?P<0.001?.Protein levels and digestible energy levels had no significant effect on body composition?P>0.05?.The above results indicate that under different nutrient conditions,the appropriate E/P of Macrobrachium nipponense is different,and the optimal E/P ratio under high-fat and high-protein conditions is higher.It is suggested that the energy substance of high fat and high protein is more effective to the protein conservation.