The U.S. Poultry & Egg Association and the USPOULTRY Foundation have completed a funded research project at Auburn University on the evaluation of animal protein meals on nutritional quality and microbial profile of the gastrointestinal tract. 

Variation in amino acid profiles and phosphorus levels in animal protein meals results in industry formulation of poultry diets based on “best estimates” because of limited scientific data. Multiple samples of animal protein meals were evaluated to determine crude protein, amino acid profile, phosphorus bioavailability and their relationship to different measures of digestibility. Microbial activity of the gastrointestinal tract was also investigated. Pepsin digestibility and the digestible enzyme assay were highly correlated with the standard ileal amino acid digestibility measure for all amino acids in 20 animal protein meals. From these data prediction, equations were calculated.


Microbial intestinal activity was found to be affected more by age (early) than by protein source. Phosphorus content of 10 animal protein meals tested was highly variable and no differences were found in bone strength measurements, suggesting that phosphorus in animal protein meals is readily available.