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By growth trail and comparative slaughter trail, three relative trails were carried out in this study to investigate the optimal essential amino acid pattern (EAAP) for ducks at different growth phases.In experiment l(Exp.l), Single Factorial Design was adopted to study the effect on growth performance and carcass traits when ducks were supplied four different EAAPs during 0~14 days old.480 Cherry Village ducks of 1 day old were randomly assigned to four different EAAPs in this experiment. There were four essential amino acid patterns, Pattern A was amino acid requirement pattern for ducks recommended by National Research Council (NRC,1994),which was DLys,100;DMet,48; DMet+Cys,82;DTrp,27;DThr,66.Pattern B was the result of He Jianhua’s study on ducks for amino acid pattern (He Jianhua,1996), which was DLys,100;DMet,53;DMet+Cys,168;DTrp,18;DThr,76.Pattern C was result of Chen Zhengling’s study on ducks (Chen Zhengling,2001),which was DLys,100;DMet,38; DMet+Cys,72 DTrp,18;DThr,70.Pattern D was the result of summarizing all the data about amino acid patterns on ducks (summarized pattern), which was DLys,100;DMet,43; DMet+Cys,77;DTrp,20;DThr,66. The base diets with 19% crude protein,2900 kcal/kg metabolic energy and 0.89% digestible lysine were given to the ducks in all treatment groups. The other amino acids were calculated according to the EAAP. Each group intake the same diet at 15 to 42 days. There were 8 replicates in each treatment with 4 male replicates and 4 female replicates per treatment, and each replicate with 15 ducks. Body weight, feed intake and feed efficiency were recorded at each weeks of age. 10 ducks were killed on 1 day old and 8 ducks from per group were killed at the of age 15 and 43 days to determine nitrogen40retention and carcass traits .The results showed that the different EAAPs have remarkable effect on performance and nitrogen retention. The average daily gain (ADG) and nitrogen retention rate were the highest in pattern A. In pattern B, the ADG and average daily feed intake (ADFI) were significantly lower than other patterns (P<0.05) . but feed/gain(F/G) was the lowest. Besides, compensatory growth occurred at 15 to 42 days in pattern B. At the end of the trial ,there were no significantly differences in body weight, liveweight gain, feed intake and feed efficiency among four treatments (P>0.05) .There were no significantly differences in the carcass composition at 14 days of age (P>0.05) but different EAAPs have some effect on crude protein(CP) and fattiness(Fat) at 42 days . For example, in pattern D, the percentage of CP was higher and the percentage of Fat was lower compared with others (P<0.05).The percentage of water and ash were similar in all treatments (>0.05). Average percentage of slaughter yield and the respective percentage of breast and leg muscle not significantly differences (P>0.05) .Considered all the parameters, using the RANK process analysis of the system SAS and the result showed that pattern A was the best EAAPs for ducks at the age of 0 to 14 days .So,we recommend the EAAP for ducks at the age of 0 to 14 days was DLys,100;DMet,48 ;DMet+Cys,82; DTrp,27; DThr,66.In experiment 2(Exp.2), 420 Cherry Village ducks at the age of 0 to 15 dayss feed the same diet, then 384 health ducks were selected to randomly assigned into four different EAAPs to study the effect of different EAAPs on growth performance and carcass traits of ducks at 15 to 42 days. There were four treatment groups, Pattern A was NRC’s result(1994),which was DLys,100 DMet,50; DMet+Cys,89; DTrp,26;DThr,67. Pattern B was the result of He Jiarihua’s study on ducks for amino acid pattern (He Jianhua, 1996),which was DLys,100;DMet,52;DMet+Cys,168; DTrp,l7;DThr,73.Pattern C was Chen Zengling’s result (2001) .which was DLys ,100; DMet,38 ; DMet+Cys,72 ;DTrp,18 DThr,70 .Pattern D was summarized by myself according to former study, which was DLys, 100; DMet,44; DMet+Cys,80;DTrp,23;DThr,67.The base diets with 15% crude protein,2612 kcal/kg metabolic energy and 0.66% digestible lysine were given to the ducks
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