ARS | Publication request: Protein digestibility evaluations of meat and fish substrates using laboratory, avian and ileally cannulated dog assays

Submitted to: Journal of Animal Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 7, 2009
Publication Date: July 7, 2010
Citation: Faber, T.A., Bechtel, P.J., Hernot, D.C., Parsons, C.M., Swanson, K.S., Smiley, S., Fahey, G.C. 2010. Protein digestibility evaluations of meat and fish substrates using laboratory, avian and ileally cannulated dog assays. Journal of Animal Science. 88:1421-1432.

Interpretive Summary: Meat and fish serve as important protein sources in the human and companion animal diet, but limited information is available on quality differences among high quality protein sources. The high quality protein substrates (beef loin, pork loin, chicken breast, pollock fillet, and salmon fillet) tested in this experiment have major differences in chemical composition but, when incorporated into a diet supplying 25% of total energy intake, result in no significant differences in apparent nutrient digestibility using the cannulated dog model. Results demonstrate that high quality proteins from mammlian, avian, and marine sources are digested in an efficient manner, leaving little residual material to be digested in the large bowel. This is not the case when protein ingredients of lower nutritive value are fed. In summary, high quality protein substrates (beef loin, pork loin, chicken breast, pollock fillet, and salmon fillet) have major compositional but relatively minor quality differences.

Technical Abstract: Fish and meat protein serves as important protein sources in the human and companion animal diets: however, limited information is available on differences in protein quality. Pollock fillet, and salmon fillet, beef loin, pork loin and chicken breast, were evaluated for protein quality and amino acid bioavailability using the cecectomized rooster and protein efficiency ratio (PER) assays. Twenty cecectomized roosters were dosed with one of the five test protein substrates. All excreta were collected, freeze-dried, and analyzed for amino acids. Amino acids in pollock fillet were more digestible (90.4%) compared to other test substrates, whereas chicken breast and salmon fillet had the lowest amino acid digestibility. Protein efficiency ratio was evaluated using one hundred 8-d old male chicks fed one of five diets containing 10% protein provided by each of the five test protein substrates. The assay was conducted as a completely randomized design: five treatments with five chicks per treatment and each treatment with four replicated pens. No differences were noted for beef loin, pork loin, salmon fillet, or pollock fillet. Among test protein sources, pollock fillet was the highest quality substrate and chicken breast the lowest based on standardized amino acid digestibility and PER data. All protein sources were of high nutritive value. This study was part of the M.S. thesis of Trevor Faber at the University of Illinois.