Dietary Effects Of Replacing Fish Meal With Clostridium Autoethanogenum Protein On Growth And Flesh Quality Of Pacific White Shrimp (Litopenaeus Vannamei) And Nutritional Improvement Strategy

1.Effects of replacing fish meal with Clostridium autoethanogenum protein in high fish meal diet on growth and flesh quality of Pacific white shrimp(Litopenaeus vannamei)This study evaluated the effects of replacing dietary fish meal(FM)with Clostridium autoethanogenum protein(CAP)on growth and flesh quality of Pacific white shrimp,Litopenaeus vannamei.A control diet was designed to contain 560 g/kg FM,then 0%,15%,30%,45%,70% and 100% of dietary FM was replaced by CAP,referring to Con,CAP-15,CAP-30,CAP-45,CAP-70 and CAP-100,respectively.The six isoproteic and isolipidic diets were fed to shrimp(2.78 g)for 8 weeks.The results showed that the replacement of dietary fish meal with CAP significantly reduced the growth performance and flesh quality of shrimp,reduced the feed intake,weight gain and survival rate,and increased the feed conversion ratio(P < 0.05);reduced the content of flesh collagen,firmness,water holding capacity,umami amino acid content,n-3/n-6 PUFAs ratio,and body surface redness and yellowness(P < 0.05).In addition,at the molecular level,CAP did not affect the muscle antioxidant enzyme genes(po and gpx)and growth-related genes(akt,pi3 k,s6k1,tor,4e-bp1)m RNA expression when30% dietary FM was replaced(P > 0.05),however,when the substitution ratio reached70%,the m RNA expression of the above genes was significantly reduced(P < 0.05).One-way analysis of variance showed that CAP can effectively replace 30% of dietary fish meal without significant effect on growth and flesh quality,but the replacement ratio reached 45% significantly reduced growth and flesh quality.In conclusion,in a basal diet containing 560 g/kg FM,30% dietary FM could be successfully replaced by CAP,while higher FM substitution decreased the growth and flesh quality of L.vannamei.2.Effects of replacing fish meal with Clostridium autoethanogenum protein with amino acid,taurine and cholesterol supplementation in the diet of Pacific white shrimpThis study evaluated the effects of replacing fish meal with CAP on the growth and flesh quality of Pacific white shrimp based on amino acid,taurine and cholesterol supplementation.On the basis of Exp.1,the diets of CAP-15,CAP-30,CAP-45,CAP-70 and CAP-100 were supplemented with microcapsulated arginine,histidine,phenylalanine,tryptophan,taurine and cholesterol to reach the same levels as the control group(CAP-0),abbreviated as Con,CAP15-A,CAP30-A,CAP45-A,CAP70-A and CAP100-A,respectively.The six isoproteic and isolipidic diets were fed to shrimp(2.78 g)for 8 weeks The results showed that there was no significant difference in feed intake,weight gain and feed conversion ratio among the three groups of control,CAP15-A and CAP30-A(P > 0.05).When the replaced level of fishmeal by CAP reached 45%,the shrimp growth performance decreased significantly.Broken line model based on WG and FCR showed that the proper replacement of dietary fish meal by CAP was 26.29% and 30.85%,respectively.Flesh crude protein,total collagen and heat-insoluble collagen contents,firmness,chewiness,shear force,body surface brightness,redness and yellowness,n-3/n-6 PUFAs ratio in CAP15-A and CAP30-A groups reached the same levels as the control group(P > 0.05).The flesh umami amino acid content in CAP100-A group was significantly lower than that in control group(P <0.05).In conclusion,with the supplementation of amino acid,taurine and cholesterol,CAP can effectively replace 30%(168 g/kg)fishmeal in a diet containing 560 g/kg fishmeal,while higher FM substitution decreased the growth and flesh quality of Pacific white shrimp.3.Effects of replacing fish meal with Clostridium autoethanogenumproteinin practical diet on growth,flesh quality and transcriptome of Pacific white shrimp(Litopenaeus vannamei)This study evaluated the effects of replacing fish meal with Clostridium autoethanogenum protein in practical diet on growth and flesh quality of Pacific white shrimp.The control diet was formulated to contain 200 g/kg fishmeal,and then dietary fishmeal was decreased to 150 g/kg,100 g/kg,50 g/kg and 0 g/kg by the isoproteinic inclusion of CAP,respectively(FM-20,FM-15,FM-10,FM-5,FM-0).In the fish meal substituted diets,micro-encapsulated tryptophan,arginine,histidine,phenylalanine,methionine and cholesterol were supplemented to reach the same levels as the control group(FM-20).The five diets were fed to shrimp(1.52 ± 0.10 g)for 8 weeks.The results indicated that the weight gain(821.7%-831.6%)and feed conversion ratio(1.45-1.47)were not significantly affected by CAP inclusion(P > 0.05),and the whole shrimp and flesh composition,flesh steaming and cooking loss,flesh total essential amino acids content,proportion of n-6 and n-3 PUFAs,total delicious amino acids content and flesh biochemical indexes showed no significant difference among all the groups(P > 0.05).When dietary fish meal was completely replaced by CAP(FM-0),flesh hardness,chewiness,gumminess,cooked shrimp body redness,yellowness,content of flesh total collagen and heat insoluble collagen decreased significantly,and the proportion of SFAs,serum glucose and triglyceride contents increased significantly(P < 0.05).The replacement of 75% of dietary fish meal by CAP did not affect flesh texture characteristics and body surface color parameters(P > 0.05).In the analysis of flesh transcriptome,the cellular community-related pathways as focal adhesion,adherens junction,tight junction,regulation of actin cytoskeleton,and the lipid metabolism-related pathways as steroid biosynthesis,arachidonic acid metabolism,linoleic acid metabolism and PPAR signaling pathways were screened out.In addition,the genes related to muscle fiber reorganization,collagen synthesis and decomposition,including ACTB_G1s,MYHs,MYL,PAN1,COL1A1,COL1A2,MMP14 were found to play important roles in maintaining high flesh firmness for Pacific white shrimp.In conclusion,with the supplementation of amino acids and cholesterol,CAP can completely replace fish meal in a practical diet containing 200 g/kg fish meal without effects on growth performance,flesh flavor,nutritional value and water holding capacity,but adversely affected flesh texture and color of shrimp.Considering the growth performance and flesh quality,the replacement level of dietary fish meal with CAP was suggested to be 75%(150 g/kg).4.Supplemental effects of functional additives in low fishmeal diets on growth and flesh quality of Pacific white shrimpThe present study evaluated the effects of supplementing taurine,creatine,hydroxyproline and Eucommia ulmoides leaf extraction in low FM diet on growth and flesh quality of Pacific white shrimp.A positive control diet(PC)and a negative control diet(NC)were designed to contain 200 g/kg(FM-20)and 100 g/kg(FM-10)FM respectively.In NC diet,CAP was included at 75 g/kg and limited amino acids and cholesterol were supplemented to reach the same levels as PC diet.Then,microencapsulated taurine(6 g/kg),creatine(16.56 g/kg),hydroxyproline(10.5 g/kg)or Eucommia ulmoides leaf extract(1.0 g/kg)were supplemented in NC diet to form another four diets,abbreviated as FM10-T,FM10-C,FM10-H,FM10-Eu,respectively.The six isoproteic and isolipidic diets were fed to shrimp(1.52 ± 0.10 g)for 8 weeks.The results showed that the addition of taurine,creatine,hydroxyproline and Eucommia ulmoides leaf extract in the NC diet had no significant effect on growth performance,whole body and flesh composition,flesh amino acids composition,proportion of n-6PUFAs and n-3 PUFAs,umami amino acid content and antioxidant properties(P >0.05).The addition of hydroxyproline significantly increased serum albumin and total protein content,and increased flesh total collagen,heat-insoluble collagen content,hardness and gumminess(P < 0.05).The addition of creatine significantly increased the contents of serum albumin,total protein,flesh heat-insoluble collagen contentand muscle fiber density(P < 0.05).However,dietary taurine and EU did not significantly affect flesh collagen content,texture and fiber density(P > 0.05),but decreased serum triglyceride and glucose content(P < 0.05).The addition of hydroxyproline significantly enriched several pathways involved in cytoskeleton composition,increased the muscle fibers density by up-regulating the expression of multiple myosin heavy chain and actin production-related genes,and increased muscle collagen content by up-regulation collagen genes,thereby improved shrimp muscle firmness.In conclusion,the supplementation of creatine and hydroxyproline in low fishmeal diet with CAP inclusion increased the muscle fiber density and flesh collagen content respectively,thereby solve the flesh firmness problem caused by low fishmeal diets.