ILEAL DIGESTIBILITY
Apparent ileal nutrient digestibility
Digestibility values for nutrients that may be metabolized in the hindgut of pigs are most correctly measured at the end of the ileum. Amino acids, starch, and fatty acids are examples of nutrients for which accurate digestibility values cannot be measured using the approach for total tract digestibility. Therefore, apparent ileal digestibility (AID) values for these nutrients are measured to estimate the absorption from the intestinal tract of the pigs. The AID of nutrients is defined as the net disappearance of ingested dietary nutrients from the digestive tract proximal to the distal ileum. Values for AID are calculated from the flow and composition of digesta at the distal ileum of pigs and by relating the total ileal outflow of nutrients to the dietary intake according to Eq. [3]:
[3] AID (%) = [(Nintake — Ileal Noutflow) / Nintake] x 100
Where Nintake and ileal Noutflow represent dietary intake of a nutrient (g/kg DM) and the ileal outflow of that nutrient (g/kg DM), respectively.
