Effect of processing methods and raw material sources on protein quality of animal protein meals

Experiments were conducted to evaluate the effect of processing systems/temperature and raw material source on protein quality of five feather meals (FM), 32 meat and bone meals (MBM) and 12 poultry by-product meals (PBPM) using digestibility and chick growth assays. True digestibility of amino acids (AA) was influenced by raw material source and type of processing system. In addition, increasing the temperature during processing generally decreased protein quality of MBM and PBPM.Several experiments were conducted to determine the order of AA limitation in MBM and PBPM using AA addition and deletion assays. The results indicated that AA limitation order in MBM protein was (1) Trp and Cys, (2) Thr, (3) Ile and Phe + Tyr, (4) Met, (5) Lys, and (6) Val and His, and AA limitation order in PBPM was (1) Cys, (2) Trp, (3) Thr and Lys, (4) Val and (5) Ile and His. The results of the AA deletion and addition assays were in general agreement although an AA deletion assay based on ideal protein was more effective than the addition assay.Three chick growth assays were conducted to determine if the digestible Lys, Met and total sulfur amino acids (TSAA) in high and low quality MBM assessed using the precision-fed cecectomized rooster assay were completely bioavailable for protein synthesis in chicks. Multiple regression slope-ratio analysis of chick growth assays indicated that almost all of the digestible Lys and Met in MBM are bioavailable for protein synthesis but suggested that some of the digestible TSAA, probably Cys, may not be bioavailable.The last study evaluated formulation of diets containing high or low-quality MBM on a total AA basis versus a digestible or bioavailable AA basis. Growth performance of chicks fed MBM diets formulated on a total AA basis was inferior to performance of chicks fed MBM or corn-soybean meal diets formulated on a digestible or bioavailable AA basis. These results indicated that formulation of diets containing MBM on a digestible or bioavailable AA basis is superior to formulation on a total AA basis.U of I OnlyETDs are only available to UIUC Users without author permissio