This experiment was conducted to study the effect of low-protein diets on production performance,serum biochemical indices and feces nitrogen content in Mule ducks.A total of 450 1-day-old Mule ducks were randomly assigned to 3 dietary treatments with five replicates and thirty ducks with each pen (50% males,50% females). The control group received the diet including the normal level of crude protein (CP)(19% CP during 1-21 day-old, 16% CP during 22-56 day-old),and the level of CP in diet of trial group Ⅰand trial group Ⅱwas decreased by 1%and 2%,respectively,while supplied with compounded amino acids.The feeding trial lasted for 56 days.The results showed that: (1)There was no significant effect of low-protein diet on average daily feed intake (ADFI), average daily gain (ADG)and feed to gain (F/G)of Mule ducks during 1 -21,22 -56 and 1 -56 day-old (P >0.05);(2)The content of total protein (TP),urea nitrogen (UN)and nuric acid (UA)in serum of ducks at 21 d and 56 d old showed tendency to descend,however,the levels of TP,UN and UA in serum among the three groups had no obvious differences (P >0.05);(3)During 1-21 day-old,the feces nitrogen content of duck in trial groupⅠand trial group Ⅱwere significantly decreased by 8.17% (P 0.05)and 21.71%,respectively during 22 -56 day-old (P <0.05 ).These results indicated that dietary protein decreased by 1% - 2% had no obvious effects on growth performance and serum biochemical indices of mule ducks,but which could significantly decrease the feces nitrogen content of ducks under the condition that amino acid in diet met the need of birds.%为研究低蛋白质日粮对白羽半番鸭生长性能、血清生化指标及粪氮含量的影响，选取1日龄白羽半番鸭450只，随机分为3组，每组5个重复，每个重复30只鸭，公母各半。对照组饲喂常规蛋白水平（CP）的日粮（1～21日龄 CP 为19％，22～56日龄 CP 为16％），试验组（试验Ⅰ组、试验Ⅱ组）在对照组日粮基础上 CP分别降低1个百分点和2个百分点同时补充合成氨基酸的日粮，试验期56 d。结果表明：1）1～21日龄、22～56日龄及1～56日龄白羽半番鸭平均日采食量、平均日增重及料重比各组间均差异不显著（P ＞0．05）。2）鸭21日龄、56日龄血清中总蛋白、尿素氮、尿酸含量呈下降趋势，但各组间均差异不显著（P ＞0．05）。3）1～21日龄，试验Ⅰ组、试验Ⅱ组鸭粪氮含量分别比对照组下降了8．17％（P ＜0．05）和15．75％（P ＜0．05），22～56日龄，试验Ⅰ组、试验Ⅱ组粪氮含量分别比对照组下降了5．64％（P ＞0．05）和21．71％（P ＜0．05）。说明在满足日粮氨基酸需要的条件下，日粮粗蛋白质降低1～2个百分点，对白羽半番鸭生长性能、血清生化指标无显著影响，但可显著降低粪中氮的含量。
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