Comparisons of amino acid availability by different methods and metabolizable energy determination of a Chinese variety of high oil corn.

TME, true amino acid availability (TAAA), AME, and apparent amino acid availability (AAAA) were determined in Chinese high oil corn (CHOC) and conventional corn (CC). The CC and CHOC contained 4.58 and 8.44% ether extract (DM basis), respectively. A precision-fed rooster assay was used in which each corn sample was tube-fed (50 g) to 16 roosters and excreta were collected for 48 h. A N-free diet and fasting methods were used to evaluate endogenous amino acid (AA) losses. Endogenous losses of 10 AA were different (P < 0.05) with the N-free and fasting methods; in most cases the mean value for the N-free treatment was greater (P < 0.05) than for the fasting treatment. The TME value for CHOC was greater than for CC (4,193 vs. 3,961 cal/g DM; P < 0.05). The true availability of aspartic acid, threonine, isoleucine, and leucine of CC and CHOC was higher (P < 0.05) for the N-free method than for the fasting method. When compared within the N-free or within the fasting method, the true availabilities of lysine, methionine, and proline were higher (P < 0.05) in CHOC than in CC, but the true availability of phenylalanine was lower (P < 0.05) in CHOC than in CC. The AAAA values, although lower, followed similar patterns as the TAAA values. The results of this study indicated that availability of AA in CHOC is equal or superior to that in CC and that the available energy for poultry is higher in CHOC than in CC.