本试验采用2×5试验设计，研究了2个能量蛋白质水平（10.91MJ/kg和18%，12.12MJ/kg和20%）和5个赖氨酸水平（0.65%，0.80%，0.95%，1.10%和1.25%）对生长前期北京鸭生产性能的影响。选用560只7日龄雄性北京鸭随机分为10组，每组8个重复，每个重复7只鸭。每组饲喂1种试验日粮，试验期为7～21日龄。结果表明：与低能量低蛋白质日粮相比，高能量高蛋白质日粮显著降低北京鸭日采食量、料重比和赖氨酸日摄入量（P＜0.05）；但此2种能量蛋白质水平日粮的料重比、蛋白质和能量的日摄入量无显著差异（P>0.05）。日粮赖氨酸水平对北京鸭日增重、料重比和赖氨酸日摄入量有显著影响（P＜0.05）。本试验采用折线模型估测2种能量蛋白质水平下7～21日龄北京鸭获得最大料重比时赖氨酸的需要量，在高、低能量蛋白质水平条件下，赖氨酸需要量占日粮百分比分别为0.90%、0.80%；占蛋白质百分比分别为4.50%、4.44%。由此得出，当日粮能量蛋白质水平发生改变时，应采用适当的赖氨酸与粗蛋白质比例配制日粮以达到最佳的生产性能。

A 2×5 factorial experiment containing two ME and CP levels (12.12 MJ/kg and 20%, 10.91 MJ/kg and 18%) and five lysine levels (0.65%, 0.80%, 0.95%, 1.10% and 1.25%) was conducted to evaluate the effects of dietary energy and protein levels on lysine requirement of Beijing ducks from 7 to 21 days of age. Five hundred and sixty 7-day-old male Beijing ducks were randomly divided into 10 groups with 8 replicates in each group and 7 ducks in each replicate. These Beijing ducks were raised with experimental diets from 7 to 21 days of age. The results showed that: compared with ducks fed low ME and low CP diet, daily feed intake, feed/gain and lysine daily intake of ducklings fed high ME and high CP diet were reduced significantly (P＜0.05), but feed/gain, energy and protein daily intake had no significant difference (P>0.05) Daily weight gain, feed/gain and lysine daily intake were affected significantly by dietary lysine level. The lysine requirements of Beijing ducks from 7 to 21 days of age for optimal feed/gain at high and low ME, CP levels which were estimated by brokenline regression analysis were 0.90% and 0.80% of diet, respectively. However, when lysine requirement was expressed as a percentage of CP, the lysine requirements for optimal feed/gain at high and low ME, CP levels were 4.50% and 4.44%, respectively. It was concluded that lysine requirement should be expressed as a percentage of dietary CP when dietary energy and protein levels were changed.