Interpretive Summary: Chicken meal is not an appropriate reference protein for estimating protein quality of ingredients used in extruded diets intended for dogs
By: Michelina Crosbie, James R Templeman, Julia G Pezzali, Glenda Courtney-Martin, Crystal L Levesque, Leslie Hancock, Preston R Buff, Daniel A Columbus, Adronie Verbrugghe, Anna K Shoveller
Metabolic availability (MA) of an amino acid (AA) is the portion of a dietary AA that is both digestible and available for protein synthesis. Peas are a commonly used protein source in grain-free dog foods, often included in large proportions. Methionine (Met) is an essential AA and the first limiting AA in peas so knowing the MA of Met in peas can ensure sufficient bioavailable Met is provided in these diets. Therefore, the objective of this study was to determine the MA of Met in peas, compared to chicken meal (CM) as a gold-standard reference protein using the indicator amino acid oxidation (IAAO) technique. The IAAO technique involves comparing the oxidation response of an ingredient to a reference protein assumed to be 100% MA. As protein synthesis is inversely proportional to oxidation, the reference protein is expected to have a lower oxidation level than the ingredient of interest. However, CM had a greater oxidation level than peas and the MA of Met in CM was 31% of that of peas. Therefore, the MA of Met in peas could not be determined indicating CM was an inappropriate reference protein, but the bioavailability of Met was greater in peas than in CM.
Read the full article in the Journal of Animal Science.