Effect Of Levels Of Tryptophan On Growth And Blood Biochemistry Indexes Of0-4Week-old Duckings

This experiment was conducted to investigate the effects of dietary tryptophan level on growth performance and biochemical indices of egg-type ducklings aged1to28days, Single factor completely randomized experimental group design, select288one day aged JinDing ducks were randomly divided into six treatment groups, each dealing with6replicates of8ducks. Weight among the groups by analysis of variance difference was not significant (P>0.05), Fed corn-soybean meal basal diet (basal diet supplemented with tryptophan level was0.239%),Group II-V basis of dietary tryptophan levels were0.260%,0.280%,0.300%,0.480%, the experiment lasted for4weeks. In the experiment the5th and28th day, the ducks were weight at the beginning of every week. For each group, ducks weight and surplus feed were record every week to calculate average daily gain and feed intake, and the ratio of feed to gain. At the end of the feeding trial,6ducks which weight closely in each replicate were randomly chosen and collect blood through jugular artery puncture, and killed to take out the liver and immune organs including spleen, bursa and thymus.The results of growth performance showed that the level of tryptophan have influenced on average daily gain, feed intake and ratio of feed to gain. And a level of0.280%was the best. Too high or too low tryptophan levels were not the best production performance of duckings to play.The results of antioxidant indexes showed that the suitable level of tryptophan significantly increased the activities of CAT,SOD,T-AOC and decreased the concentration of MDA in serum and liver(P<0.05).There were not significantly effected on GSH-PX in5day serum (P>0.05),0.280%level of tryptophan significantly increased the concentration of GSH-PX in5day liver and in28day serum and liver (P<0.05). The tryptophan level of0.280%was best.The results of serum hormone indexes showed that the suitable level of tryptophan increased the concentration of T3, T4, of GH in serum, while decreased the concentration of Cort, from the entire experimental period, integrated the5th and28th day,0.280%and0.300%level of tryptophan significantly increased concentrations of T3, T4in serum (P<0.05), there were not significantly influenced on GH in5day serum (P>0.05), while significantly decreased the concentration of Cort in serum (P<0.05).The results of lipids and glucose metabolism in serum indexes showed that the suitable level of tryptophan decreased concentrations of glucose and lipid concentrations in serum of ducklings. The5th day,the level of0.280%tryptophan significantly decreased the concentration of TC and TG in serum (P<0.05), There was not significantly influenced on GLU (P>0.05).The28th day the level of0.280%tryptophan significantly decreased the concentration of GLU and TC in serum(P<0.05), the level of0.300%tryptophan significantly decreased the concentration of TG in serum (P<0.05).The results of protein metabolism indexes showed that the suitable level of tryptophan increased concentrations of TP and ALB,and decreased concentrations of BUN in serum of ducklings.The5th day there was not significantly influenced on TP (P>0.05), the level of0.280%tryptophan significantly increased concentrations of ALB in serum and significantly decreased the concentration of BUN. The28th day the level of0.280%tryptophan significantly increased concentrations of TP in serum and significantly decreased the concentration of BUN (P<0.05).The level of0.300%tryptophan significantly increased concentrations of ALB in serum (P<0.05).The result of serum immune indexes showed that,the suitable level of tryptophan significantly increased the concentrations of IgA,IgG and interleukin-2(IL-2) in the28th serum (P<0.05), significantly decreased the concentrations of IgM(P<0.05).But there was not significantly influenced on interleukin-2(IL-2) in the5th serum(P>0.05), Tryptophan levels in the range of0.280%to0.300%.The result of immune organ indexes showed that,the suitable level of tryptophan significantly increased the thymus,spleen and bursa index of the28th day duckings (P<0.05). But there was not significantly influenced on the thymus index, spleen index and bursa index of the5th day duckings (P>0.05). Tryptophan levels in the range of0.280%to0.300%.These results combined with considering production performance and blood biochemistry indexes, the optimal level of0-4week-old ducklings diet tryptophan0.280%to0.300%.