Interactive effects of dietary apparent metabolizable energy, crude protein, and lysine levels on growth and slaughter performance of starter Pekin ducks.

A 4 × 3 × 3 factorial experiment was conducted to evaluate the interactive effects of dietary AME (2,750, 2,900, 3,050, and 3,200 kcal/kg), CP (17, 18.5, and 20%), and Lys (0.8, 1.05, and 1.3%) levels on growth and slaughter performance of starter Pekin ducks (1-14 d). A total of 2,304 one-day-old White Pekin ducks were randomly assigned to 36 treatments (4 replicates of 16 birds). At 14 d, ADG, ADFI, FCR, abdominal fat, breast meat, and leg meat yields were measured. As a result, increasing dietary Lys from 0.8 to 1.05% increased breast and leg muscle yields (P < 0.0001). CP × Lys interactions were observed for ADG and ADFI (P < 0.0001). Increasing CP improved ADG at 1.05 and 1.3% Lys, but reduced ADG and ADFI under Lys deficiency (0.8%). An AME × Lys interaction was found for ADFI (P = 0.0447). Increasing AME had no effect at 0.8% Lys, but reduced ADFI at 1.05 and 1.3%Lys. Abdominal fat percentage was affected by AME × CP (P = 0.0041) and AME × Lys (P = 0.0017) interactions. At 3,050 and 3,200 kcal/kg AME, increasing CP or Lys reduced abdominal fat, whereas no effects were observed at 2,750 kcal/kg AME. A three-way interaction among AME, CP, and Lys affected FCR (P = 0.0077), where increasing CP increased FCR at 2,750 and 2,900 kcal/kg AME with 0.8% Lys, but decreased FCR at 2,750 kcal/kg AME with 1.3% Lys. Quadratic models indicated optimal levels of 2,995 kcal/kg AME, 18.65% CP, and 1.20% Lys for maximum ADG, and 3,199 kcal/kg AME, 19.58% CP, and 1.15% Lys for minimum FCR. In conclusion, dietary AME, CP, and Lys exhibited interactive effects on growth and slaughter performance of starter Pekin ducks.