Protein and amino acids play crucial roles in reproductive performance of sows (Kim et al., 2009). Pettigrew and Yang (1997) reported that an adequate supply of protein and amino acids during gestation allowed sows to maintain their productivity, and that high body protein content of sows could maximize milk production and subsequent reproductive performance. NRC (1998) recommended 12.9% CP in gestation diets for gilts (average 125 kg of BW at breeding). However, modern gilts, genetically improved to have large litter and high milk production, require more nutrients to carry on normal