Determination and correlations of standardized ileal amino acid digestibility with chemical composition of corn in broilers at 13 and 28 days of age

This study aimed to determine the standardized ileal amino acid digestibility (SIAAD) of ten corn varieties from different regions in China in broilers at 13 and 28 days of age and to investigate the Correlations between SIAAD and the chemical composition of corn. Ten semi-purified test diets and one nitrogen-free diet were designed to feed broilers in two phases. 396 broilers were split into 6 replicates, with 6 broilers each during the starter phase (11-13 d). The later phase (25-28 d) had 264 broilers in 6 replicates with 4 broilers each. The ileal digesta were collected to determine the SIAAD at 13 d and 28 d. Correlation analysis were performed to assess the relationships between SIAAD and corn chemical composition. Most SIAAD values significantly increased from 13 d to 28 d (P<0.05). Correlation analysis revealed that the most SIAAD values were positively correlated with crude ash (Ash) and crude protein (CP), but negatively correlated with ether extract (EE) and crude fiber (CF). In broilers, Most SIAAD values of corn were significantly higher at 28 days of age than at 13 days of age (P < 0.05), except for Thr, Gly, Cys, and Leu.