MATHEMATICAL-ANALYSIS OF APPARENT ILEAL DIGESTIBILITY VALUES OF AMINO-ACIDS IN FEEDSTUFFS FOR PIGS

The aim of the present study was to investigate within and among feedstuffs the variation of apparent ileal digestibility of amino acids. The interest was in developing models which estimate the apparent amino acid digestibility of feedstuffs. These equations can be useful for practical feed formulation, possibly in combination with in vitro techniques. For mathematical analysis, literature data on apparent ileal digestibility of protein and individual amino acids in feedstuffs were collected in a database (290 batches of 40 different feedstuffs). From this database the apparent ileal digestibility for each amino acid was described in an equation which contained two variables; the apparent ileal digestibility value of protein of the different feedstuffs and the reciprocal of the relative contribution of amino acids to the protein in the feedstuff. The former variable reflects the apparent amino acid digestibility values. The latter variable relates to the deviation in amino acid composition of endogenous protein and feed protein. In the analysis each individual observation was included. Individual feedstuffs or different experimental techniques were not studied separately. The explained part of the variance (R2) of most of the amino acids ranged from 0.6 to 0.8. The models, which describe the variation in apparent digestibility among amino acids, were also used to estimate the amino acid profile of endogenous protein.