A broiler chick bioassay was carried out with forty eight -day-old Arian-broiler chickens to study the e ect of site
sampling on metabolizable energy (ME) and amino acid digestibility. The test diet contained corn and soybean meal as the
major ingredients. Three next treatments were formulated to contain barley, wheat and wheat screening as the test
ingredients at a level of in the test diet. Chromic oxide was included in all diets as an indigestible marker. Apparent
metabolizable energy (AME) and nitrogen-corrected apparent metabolizable energy (AMEn) based on excreta were
significantly higher ( . ) than ileal AME and AMEn in barley. With the exception of histidine, digestibilities of amino
acids based on excreta were numerically higher than the ileal value. Significant di erences between ileal and excreta-based
digestibility of aspartic acid, arginine, threonine, lysine, valine and methionine indicating on a net catabolism of these amino
acids in the large intestine. The current study suggests that determination of amino acid digestibility and metabolizable energy
based on excreta collection will overestimate amino acid and energy availabilities in all test ingredients.
کلید واژگان :
amino acids digestibility, energy value, excreta, ileal
