ARS | Publication request: STANDARDIZING DIGESTIBILITY RESULTS ACROSS LABS: A POSSIBLE APPROACH

Submitted to: Electronic Publication
Publication Type: Other
Publication Acceptance Date: March 2, 2008
Publication Date: March 2, 2008
Repository URL: http:////www.ars.usda.gov/sp2UserFiles/Place/36553000/pdf's/022808%20MBH%20Standardizing%20Digestibility.pdf
Citation: Hall, M., Mertens, D.R. 2008. Standardizing digestibility results across labs: a possible approach. Available: http://www.ars.usda.gov/sp2UserFiles/ Place/36553000/pdf's/022808%20MBH%20Standardizing%20Digestibility.pdf.

Technical Abstract: We present approaches for measuring digestibility of feed fractions (extents of digestion at fixed time points or rates), particularly for fermentation assays, generate values that vary within and among labs, and among methods. This variation does not allow for great precision in specifying digestibility values. The variation in measured values can reduce the accuracy of predictions by energy calculations and models, particularly if the equations are sensitive to the input, but were not calibrated to the range of values produced by a method or lab. However, labs are frequently able to rank feeds similarly, even though the values they generate may differ. We propose that it may be possible to standardize digestibility results if labs include feedstuff standards representing a range of digestibilities for a feed fraction for a feed type in each fermentation run. Results of the standard feeds could be used to rank feeds as high, medium, or low. These categorical grades could then be assigned a numeric digestibility value that is consistent with the range of values utilized in equations/models. Use of a ranking system based on use of common fermentation standards across labs could increase the coherence and applicability of digestibility values by reducing the effects of the variation inherent in biologically based assays.