The interactive effects of threonine and crude protein level on apparent nutrients digestibility and nitrogen balance in local Muscovy ducks

This study aimed to determine the effects of threonine (Thr) and crude protein (CP) on the apparent nutrients, amino acid digestibility, and nitrogen balance of local Muscovy ducks at 8 and 10 weeks of age. The study was a 3x2 factorial design for two phases with three levels of CP (17, 18, and 19% CP) and two levels of Thr (0.7 and 0.8% Thr) for the first phase while three levels of CP (15, 16, and 17% CP) and two levels of Thr (0.5 and 0.6% Thr) for the second phase. The birds were fed and given water ad libitum for the entire experiment. The results showed that CP and Thr increased apparent nutrient digestibility, especially for DM digestibility (P < 0.05). Besides, Thr addition also increased OM, and NDF digestibility (P