| With the rapid development of aquaculture,the demand for fishmeal is increasing.However,the fishmeal resource is limited,and the price continues to rise,which makes it urgent to exploit suitable and sustainable protein sources to decrease fishmeal inclusion.This study was conducted to investigate the effect of replacing fishmeal with chlorella meal in high fishmeal diet and practical diet on the growth,nutrient utilization,body color,and flesh quality of L.vannamei,to explore the potential of chlorella meal as a substitute protein source for fishmeal in shrimp diet.Based on the above results,functional additives such as hydroxyproline and creatine were supplemented in a low fishmeal diet with high chlorella meal inclusion to improve the growth and flesh quality of Pacific white shrimp.1.Effects of replacing fish meal with chlorella meal in high fishmeal diet on growth and flesh quality of Pacific white shrimp(Litopenaeus vannamei)This study was conducted to investigate the effects of replacing fishmeal(FM)with Chlorella Sorokiniana meal on growth and flesh quality of Pacific white shrimp,Litopenaeus vannamei.A control diet was formulated to contain 560g/kg FM,and then chlorella meal was used to replace 0%(C-0),20%(C-20),40%(C-40),60%(C-60),80%(C-80)and 100%(C-100)of dietary FM,respectively.The six isoproteic and isolipidic diets were fed to shrimp(1.37±0.02g)for 8 weeks.The results showed that weight gain(WG)and protein retention(PR)of C-20 group were significantly higher than those of C-0 group(P<0.05),while no significant differences were observed in WG and PR between C-0 and C-40 groups(P>0.05).When the replaced level of FM by chlorella meal reached 60%,the WG of shrimp decreased,and feed conversion ratio(FCR)increased significantly(P<0.05).The quadratic regression analysis indicated that substituted fishmeal levels with chlorella meal were 20.50% and 28.25%,respectively,to obtain the highest WG and lowest FCR.In C-40 and C-60 groups,the body surface presented higher redness than the control(P< 0.05).No significant differences in the whole body,SOD,T-AOC,GSH-PX activities,MDA contents,total collagen content,steaming loss,texture property,free delicious amino acids contents,PUFAs,and n-3/n-6 PUFAs in flesh were observed among the three groups of C-0,C-20,and C-40(P > 0.05).Compared to the control group,C-60,C-80 and C-100 groups showed lower flesh hardness,chewiness,shear force,and higher steaming loss and resilience(P<0.05).There were no significant differences in serum TP,TG,GLU,and ALB contents,boiling loss,freezing loss,total free amino acids,SAFs and MUFAs among all the groups(P>0.05).Conclusively,in a diet containing 560g/kg FM,chlorella meal could replace 40% dietary FM without negative effects on the growth and flesh quality,while increase the body redness of white shrimp.2.Effects of replacing fish meal with chlorella meal in practical diet on growth and flesh quality of Pacific white shrimp(Litopenaeus vannamei)This study was conducted to investigate the effects of replacing fishmeal with chlorella meal in practical diet on growth and flesh quality of Pacific white shrimp.A control diet was formulated to contain 200 g/kg FM(FM-20),and then chlorella meal was used to decrease the amount of fishmeal to 150 g/kg(FM-15),100 g/kg(FM-10),50 g/kg(FM-5)and 0(FM-0),corresponding to the replacement of 25%,50%,75% and100% of dietary FM,respectively.In the fishmeal substituted diets,micro-encapsulated histidine,methionine and cholesterol were supplemented to reach the same levels as the control group(FM-20).The five isoproteic and isolipidic diets were fed to shrimp(1.37±0.02g)for 8 weeks.The results showed that no significant difference were observed in weight gain and FCR between the control group and FM15 group(P>0.05),but when the replaced level of FM by chlorella meal reached 50%,weight gain,protein and lipid retention,and n-3/n-6 PUFAs in flesh were significantly lower and feed conversion ratio were significantly higher than those of FM20 group(P<0.05).There were no significant differences in survival,feed intake,condition factor,meat yield,apparent digestibility coefficients of dry matter and crude protein and flesh shear force between control group and all substituted groups(P>0.05).The yellowness of shrimp in FM-15 group was significantly higher than that of the control group(P<0.05).When chlorella meal replaced 100% of dietary FM,the redness(a*)and yellowness(b*)of shrimp,and essential amino acid content of flesh were significantly decreased(P<0.05).No significant differences in muscle moisture,crude protein,crude lipid,total collagen content,serum biochemical indexes,flesh texture characteristic(hardness,springiness,ect),water-holding capacity,antioxidant capacity,total amino acid content,free amino acid,fatty acid composition and muscle fiber density were found among all the groups(P>0.05).Conclusively,with the supplementation of cholesterol and limiting amino acids,chlorella meal could replace 25% of dietary FM in practical diet containing 200g/kg FM without negative effects on the growth performance,and replace 75% of dietary FM without adverse effects on flesh quality of white shrimp.3.Supplemental effects of hydroxyproline and creatine in high chlorella meal-low fishmeal diet on growth and flesh quality of Pacific white shrimp(Litopenaeus vannamei)This study was conducted to investigate the effects of supplementing essential amino acid,hydroxyproline and creatine in high chlorella meal diet on growth and flesh quality of Pacific white shrimp.The positive control diet(PC)was formulated to contain 330g/kg FM and 253.3 g/kg chlorella meal,and then chlorella meal was used to replace two-thirds of dietary fishmeal to from negative control diet(NC)containing110g/kg FM and 506.5g/kg chlorella meal.Based on the NC diet,micro-encapsulated histidine,isoleucine,lysine,methionine and cholesterol were supplemented to reach the same levels as the PC group,named as AC diet.In addition,micro-encapsulated hydroxyproline(12.0 g/kg)and creatine(12.0 g/kg)were added individually or jointly in AC diet(AC-H,AC-C and AC-H+C)to form another three diets.The six isoproteic and isolipidic diets were fed to shrimp(1.20±0.02g)for 8 weeks.Compared to the PC group,the WG of NC group were significantly decreased,and FCR was significantly increased(P<0.05).The WG of AC group showed no significant difference with NC group(P>0.05),but the addition of hydroxyproline or(and)creatine increased the WG and decreased FCR significantly(P<0.05).Compared to the PC group,the body a*,b*,ADCP,flesh heat insoluble collage collagen content,hardness,T-AOC content,SOD and GPx activity,lysine content,free glycine content and flesh fiber density of NC group were significantly decreased(P<0.05),and the steaming loss was significantly increased(P<0.05).The supplementation of amino acid,cholesterol,hydroxyproline and creatine,improved the above indexes and reach the similar levels to the PC group(P>0.05).Compared to the PC group,the ratios of C18:2,C18:3 and C20:3 in flesh of all other groups were significantly increased(P<0.05),while the ratios of C20:5,C22:6and n-3/n-6 PUFAs were significantly decreased(P< 0.05).The supplementation of essential amino acids,hydroxyproline and creatine did not significantly affect protein and lipid retention,flesh shear force and fatty acid composition(P>0.05).There was no significant difference in flesh moisture,crude lipid,crude ash,heat soluble collagen and LA content,cooking and freezing loss,serum biochemical indexes,total essential amino acid content and delicious amino acid content among all the groups(P>0.05).In conclusion,in a diet containing 110 g/kg FM and 506.5 g/kg chlorella,the supplementation of limiting amino acids,cholesterol,micro-encapsulated hydroxyproline and creatine could improve the growth performance and flesh quality of shrimp.4.Supplemental effects of hydroxyproline and creatine in fishmeal-free diet on growth and flesh quality of Pacific white shrimp(Litopenaeus vannamei)This study was conducted to investigate the effects of supplementing hydroxyproline and creatine in fishmeal-free diet on growth and flesh quality of Pacific white shrimp.The positive control diet(FM20)was formulated to contain 200 g/kg FM,and then chlorella meal was used to replace 100% of dietary FM with the supplementation of micro-encapsulated histidine,isoleucine,lysine,methionine and cholesterol to form the negative control diet(FM0).Then,micro-encapsulated hydroxyproline(12.0 g/kg)and creatine(12.0 g/kg)were added individually or jointly in FM0 diet(FM0-H,FM0-C and FM0-H+C)to form another three diets.The five isoproteic and isolipidic diets were fed to shrimp(1.20±0.02g)for 8 weeks.When chlorella meal replaced all the dietary FM,the WG,ADDM,ADCP and serum SOD activity were significantly decreased,while FCR,flesh steaming loss and LA content were significantly increased in FM-0 group(P<0.05).Compared to FM0 group,FM0-H+C group presented higher WG(+7.0%)(P=0.066)and lower FCR(-0.09)(P=0.053),while the body a*,ADDM,ADCP,serum SOD and GPx activity,flesh hardness and GPx activity were also significantly increased and flesh LA content was significantly decreased(P<0.05),reaching the similar levels to the PC group(P>0.05).When chlorella meal completely replaced dietary FM,the ratios of C18:2,C18:3 and C20:3 in flesh were significantly increased(P<0.05),while the ratios of C20:5 and n-3/n-6 PUFAs were significantly decreased(P<0.05).The supplementation of hydroxyproline and creatine had no significant effects on flesh fatty acid composition(P>0.05).No significant differences in conditional factor,body L* and b* value,flesh proximate composition,collagen content,cooking and freezing loss,serum T-AOC,MDA and LA content,flesh T-AOC,SOD and MDA activity,flesh hydrolyzed amino acid and free amino acid content were detected among all the groups(P>0.05).Conclusively,in a fishmeal-free diet,the supplementation of hydroxyproline and creatine could improve the apparent digestibility of dry matter,protein and flesh hardness,body redness,and tend to promote the growth of shrimp. |
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