Effects Of Dietary Lysine Levels On Growth And Lysine Metabolism In Leuciscus

The present study was conducted to evaluate the effect of lysine on growth,feed utilization,lysine metabolism,nutrition comsition of Leuciscus.Freshwater aquaculture fish Leuciscus as important research object.The main research results are as follows:Nine hundred healthy Leuciscus were randomly divided into 6 groups with3 repetition per group and 50 fish in each repetition.Six isoenergetic(17 MJ/kg)and isonitrogen(37 %CP)diet by different levels of lysine(1.82 %,2.27 %,2.72%,3.17 %,3.62 %,4.07 %)were preparred to feed the fish for 8 weeks.These results showed that the weight gain rate and the specific growth rate of 2.27 %,2.72 %,3.17 %,3.62 %,4.07 %group of Leuciscus were significantly higher than that of control group with elevated levels of lysine(P<0.05).The effect on feed dfficiency and protein depsosition rate of Leuciscus was significantly different a-mong control group,2.27 %group and 2.72 % group,which was higer with the growth of lysine(P<0.05).The effect on protein efficiency rate of Leuciscus was si-gnificantly different among control group,2.27 % group and 3.17 % group,which was higer with the growth of lysine(P<0.05).Protein deposition rate of 3.17% group of Leuciscus was apparently higher than that of control group.After 8 w of feeding trials,lysine metabolic enzyme content in serum,LKR,AASS activity and transport carrier CAT1 m RNA and AASSm RNA relative expressionwere determined,Discuss the effect of feed lysine level affect Leuciscus metabolic enzyme activity.These results showed that under this experimental condition,feed lysine level has a significant influence on Leuciscus metabolic enzyme activity.Under the same protein level,with the improvement of lysine,liver serum total protein,albumin,presents the first after rising downward trend(P<0.05).Feed lysine level significantly affected cereal third transaminase(ALT)and aspertate aminotransferase(AST)activities(P<0.05).When the lysine level in feed adequate or deficiency,AST and ALT activity increase.Feed lysine level significantly affected urea nitrogen content(P<0.05).Urea nitrogen content increased with the increase of lysine level is on the decline.When 3.17 % lysine level,IGF-1 on the serum,total cholesterol and total free amino acid was significant difference with control group(P<0.05).In serum and liver,AASS and LKR increased with the increase of lysine level increased,2.72 %,3.17 % and 3.62 % in the group were significantly higher than the control group(P<0.05).CAT1 and AASSm RNA expression quantity as lysine level rises,3.17 %,3.62 % and 4.07 % in the group were significantly higher than the control group(P<0.05).Under this experimental condition,feed lysine level of Leuciscus nutrition results show that:Muscle protein content of Leuciscus was higher as feed lysine level riing,and the best result came out when the lysine level was 3.62 %(P<0.05).The content of lysine?histidine and glutamic acid of Leuciscus muscle was significantly higher than that of control group in 3.17 % group.The content of aspartic acid and arginine in 2.27 % group was significantly higher than that in control group.The content of leucine in 3.62 % group was significantly higher than that in control group.In this experimental conditions,adding lysine in feed can effectively improve growth performance,feed utilization,lysine metabolism and muscle protein synthesis of Leuciscus.Based on the average weight gain rate and protein efficiency with regression equation analyses,the lysine leves suitablely in feed of Leuciscus were 3.17 %-3.26 %.