Correlation between pepsin digestibility, metabolisable energy and digestibility coefficients of amino acids from...

1. Three experiments were conducted to evaluate the predictive value of pepsin digestibility for estimating apparent metabolisable energy corrected for nitrogen balance (AMEn) and true ileal digestibility coefficients of amino acids (TIDCAA) in animal-origin meals (AOM) for broilers.2. Two poultry offal and bone meals (POBM1 and POBM2) and one swine offal and bone meal (SOBM) were assessed using in vivo and in vitro methods.3. In vivo trials determined AMEn and TIDCAA using a completely randomised design with 16 treatments, 8 replicates and 10 birds per replicate, while pepsin digestibility was measured in vitro.4. Pepsin digestibility showed variable correlations with nutrient values. In POBM1, only arginine showed a significant negative correlation with AMEn and TIDCAA. For POBM2, significant positive correlations with TIDCAA were observed only for lysine, histidine and glycine and for SOBM, a quadratic pattern was observed for TIDCAA, with no significant effect on AMEn.5. The results indicated that pepsin digestibility may be a useful predictor of amino acid digestibility in AOM, but its reliability for estimating AMEn was limited and dependent on ingredient type.