Availability of amino acids in high-oil corn

True digestibility of amino acids, bioavailability of Lys, and TME(n) in three types of high-oil corn (HOC) and one conventional corn (CC) were determined. The CC, HOC1, HOC2, and HOC3 contained 4.3, 5.9, 6.6, and 9.5% ether extract, respectively, on a DM basis. True digestibility of amino acids was determined using the precision-fed cecectomized rooster assay in which each corn sample was tube-fed (30 g) to nine roosters and excreta were collected for 48 h. True digestibility of most amino acids in HOC2 and HOC3 were significantly higher (P less than or equal to 0.05) than those in CC and HOC1. Mean digestibility of 15 amino acids in HOC2 and HOC3 was 91% compared to 80% for CC and HOC1. The TME(n) values (kilocalories per gram DM) of CC, HOC1, HOC2, and HOC3 were 3.883, 4.024, 4.038, and 4.140, respectively. Lysine bioavailability was assessed using a slope-ratio chick growth assay in which a Lys-deficient crystalline amino acid diet was supplemented with 0, 0.1, or 0.2% L-Lys from L-Lys(.)HC1 to provide a standard curve. Six additional dietary treatments consisted of supplementing the basal diet with 28 or 56% of CC, HOC2, or HOC3. The nine diets were fed to four replicate groups of six chicks from 8 to 18 d posthatching. Lysine bioavailability was calculated using multiple regression slope-ratio methodology where Y was weight gain and X was intake of Lys from the L-Lys(.)HC1 or a corn. Supplementation of the basal diet with L-Lys.HC1, CC, HOC2, or HOC3 yielded linear (P less than or equal to 0.001) growth responses. Bioavailability values (percentage) for the Lys in CC, HOC2, and HOC3 relative to the Lys in L-Lys(.)HC1 were 65 +/- 10, 72 +/- 10, and 91 +/- 8, respectively. The results of this study indicated that digestibility of amino acids and bioavailability of Lys in HOC are equal to or greater than those in CC.