Study On The Requirement Of Arginine In Juveniles Of Procambarus Clarkii

Arginine is one of the essential amino acids of aquatic animals and plays an important role in the growth of animals.Like other fish and shrimps,Crayfish is an ammonia-excreting animal.There is no urea cycle in the body,and the ability to synthesize arginine is weak.There may be special need for the requirement of arginine.Juvenile is an important stage of crayfish growth and development,and plays an important role in subsequent growth and development.Therefore,for the healthy aquaculture and accurate feeding of Procambarus clarkia,the need of arginine in the youth of it has important practical implications.In this experiment,the effects of different arginine levels on growth performance,body composition,food value,and health status were studied by adding L-arginine to the diet of juvenile Crayfish.The level of dietary arginine provides certain scientific guidance for the formulation of juvenile diets for Procambarus clarkia.In this experiment,432 Crayfish weighing 3.51 ± 0.01 g were used as experimental animals and were randomly divided into 6 groups,namely I,II,III,IV,V and VI.The number of repetitions in each group was 6.Repeat 12 tails.Pre-feeding for 1 week to the formal test period after the shrimps were adapted to the environment of the aquaculture tank,the same basal diet was fed in the pre-test period;the test period was 4 weeks,and the experimental diet was fed,and the actual arginine levels in the diets of each group were respectively were 2.02 %,2.15 %,2.43 %,2.54 %,2.65 % and 2.79 %,and the feeds in each group were isonitrogenous.The initial and final body weight,body length and feed intake were recorded,and the hepatopancreas,shrimp shell,back muscles and hemolymph were collected for correlation analysis after the end of the test period.The main test results are as follows:1.Effects on growth performanceGroup IV feed intake was significantly higher than Group I,Group II,and Group VI feed intake(P < 0.05).The meat weight ratio of Group V was significantly higher than that of Group III and Group IV.On the other hand,weight gain and specific growth rates increased first and then decreased with increasing dietary arginine levels,but there was no significant difference between the groups(P >0.05).It can be seen that different levels of arginine in the diet will have an impact on the growth performance of juvenile Crayfish.Appropriate arginine levels can significantly increase feed intake and meat weight rate.Taking the weight gain rate as the evaluation index,it can be concluded that the suitable arginine content in the crayfish compound feed is 2.40 %(calculated as dry matter),accounting for 7.64 %of the feed protein,and the arginine/lysine ratio is 1.45 / 1.2.Effects on the mineral content of shrimp shellsThe calcium content in shrimp shells of groups III and V was significantly higher than that of the other four groups(P < 0.05).With the increase of arginine content,the iron element in the shell of Crayfish juvenile shrimp showed a trend of first decreasing and then increasing,and the iron content in the shrimp shell of group V was significantly lower than that of groups I,II and VI(P < 0.05).The zinc content of shrimp shells in group VI was higher than that in groups I,IV and V(P <0.05).The content of manganese in shrimp shells was significantly different among the groups(P < 0.05),and the group with the lowest content was group IV.It can be seen that different arginine levels in the diet have significant effects on the deposition of iron,zinc,manganese and calcium in the shells of juvenile Crayfish prawns,and the overall performance is a trend of first decreasing and then increasing,but no significant dose-effect relationship was found.3.Effects on free amino acid content in hemolymphThe content of free aspartic acid in the blood lymph of groups I and V was lower than that of group III(P < 0.05).In addition,the content of aspartic acid in Group II was higher than that in Group I(P < 0.05).The content of free glutamate in the blood lymph of group IV was higher than that of groups II,III and V.The content of free glycine in the blood lymph was significantly higher in Group IV than in Groups I,II,V,and VI(P < 0.05).The content of free histidine in the blood lymph of Group VI was significantly lower than that of the other 5 groups(P <0.05).The above shows that the content of arginine in the diet will affect the absorption and deposition of free aspartic acid,glutamic acid,glycine and histidine in the hemolymph of juvenile Crayfish,but there is no obvious regularity in the change trend.4.Effects on edible value of back muscles of shrimpThe zinc of the content in the back muscles of group V was higher than that of group I(P < 0.05);the manganese content of group III,group IV and group V were significantly different from each other(P < 0.05),the fourth group has the most content.The crude fat content of back muscles in groups I,II,V and VI was lower than that in group IV(P < 0.05).Compared with groups IV and VI,the content of glutamate and glycine in the back muscles of group III was the highest(P < 0.05),and the content of glycine in the back muscles of group III was significantly higher than those of groups I and II(P < 0.05).Except for groups V and VI,the isoleucine content in group III was significantly higher than the other three groups(P < 0.05).Compared with group II and group III,the content of arginine in back muscle of group IV was lower(P <0.05).It can be seen that the level of arginine in the diet will have an impact on the edible value of the back muscles of juvenile Crayfish.A suitable dietary arginine level will increase the crude fat deposition in the back muscles of juvenile crayfish.With the continuous increase of arginine content in the diet,the contents of zinc and manganese in the back muscles showed a first increase and then a decrease.The trend of change was basically opposite to that in shrimp shells.It may be that the level of arginine in the diet affected the distribution of zinc and manganese in juvenile Crayfish prawns.In addition,glutamate,glycine,isoleucine and arginine were highest in the back muscles of juvenile Crayfish larvae when the arginine level in the diet was 2.43%.5.Effects on health conditionsSerum SOD activity in groups Ⅰ,Ⅱ and Ⅲ was significantly higher than that in groups Ⅳ,Ⅴ and Ⅵ(P < 0.05).Among the antioxidant indexes of hepatopancreas,SOD of hepatopancreas in groups Ⅲ and Ⅳ was higher than that in the other 4 groups(P < 0.05).However,the content of MDA in the hepatopancreas of groups III,IV and V was significantly lower than that of groups I and II(P <0.05).Compared with groups I and II,the activity of ceruloplasmin in serum of group IV was the highest(P < 0.05).The activity of AKP in the hepatopancreas was highest in groups Ⅳ and Ⅵ,and the activity in group Ⅳ was higher than that in groupsⅠand Ⅴ(P < 0.05).Although different arginine in the diet had no significant effect on ACP(P > 0.05),the change trend was basically the same as that of AKP in the hepatopancreas.The serum NOS activity in group III was higher than that in groups I,V and VI(P < 0.05).No significant difference was found among the groups(P > 0.05).In the intestinal sections of group I and VI,the epithelial tissue cells were necrotic and shed;compared with groups I,II and IV,the connective tissue in groups III,V and VI was looser,and the surrounding muscle bundles were more complete;III The group had the highest number of small intestinal folds.The above shows that different levels of arginine in the diet can affect the health status of juvenile Procambarus clarkia.Appropriate dietary arginine level can improve the antioxidant capacity of serum and hepatopancreas of juvenile crayfish.When the level of arginine in the diet was 2.43 %,the activities of ceruloplasmin and nitric oxide synthase in serum and alkaline phosphatase in the hepatopancreas of juvenile crayfish were the highest.Based on the above research results,this experiment can draw the following conclusions:(1)The appropriate level of arginine in the diet can significantly increase the feed intake and meat weight rate of juvenile crayfish.Evaluation indicators,the suitable arginine content in crayfish compound feed is 2.40 %(dry matter),accounting for 7.64 % of feed protein,and the ratio of arginine/lysine is1.45/1.(2)Different levels of arginine in the diet will affect the distribution of zinc and manganese in the shell and back muscles of the juvenile crayfish;The content of free aspartic acid,glutamic acid,glycine and histidine in the hemolymph of juvenile shrimp had significant effects.(3)The level of arginine in the diet may improve the food value of Procambarus clarkia juveniles by increasing the content of crude fat and flavor amino acids in the back muscles of juveniles.(4)The level of arginine in the diet will affect the health of the juvenile crayfish.From the perspective of the antioxidant capacity and non-specific immunity of the shrimp,the dietary arginine content of 2.43 % is more suitable.