Threonine requirement of White Pekin ducks from hatch to 21d of age

1. A dose-response experiment with 5 dietary threonine concentrations (5.0, 5.8, 6.6, 7.4 and 8.2g/kg) was conducted to estimate the threonine requirement of White Pekin ducks from hatch to 21d of age. 2. A total of 240 one-d-old male White Pekin ducks were allotted to 5 experimental treatments and each treatment contained 6 replicate pens with 8 ducks per pen. Ducks were reared in raised wire-floor pens from hatch to 21d of age. At 21d of age, growth performance and intestinal morphology were determined. 3. The weight gain and feed intake of Pekin ducks increased and feed/gain of these birds decreased linearly or quadratically as dietary threonine increased from 5.0 to 8.2g threonine/kg. Compared to ducks fed on diets containing 5.0g threonine/kg, ducks given diets containing 7.4g threonine/kg had higher villus height in duodenum, jejunum and ileum. 4. The threonine requirements for weight gain of White Pekin ducks from hatch to 21d of age was estimated to be 6.72g/kg when dietary crude protein concentration was 189.8g/kg and threonine supply was critical for maintaining intestinal structure of these birds.