Evaluation of the National Research Council (2001) dairy model and derivation of new prediction equations. 2. Rumen degradable and undegradable protein

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dc.contributor.authorWhite, Robin R.en
dc.contributor.authorRoman-Garcia, Y.en
dc.contributor.authorFirkins, J. L.en
dc.contributor.authorKononoff, P.en
dc.contributor.authorVandeHaar, M. J.en
dc.contributor.authorTran, H.en
dc.contributor.authorMcGill, Tyleren
dc.contributor.authorGarnett, R.en
dc.contributor.authorHanigan, Mark D.en
dc.contributor.departmentDairy Scienceen
dc.date.accessioned2019-10-07T13:35:52Zen
dc.date.available2019-10-07T13:35:52Zen
dc.date.issued2017-05en
dc.description.abstractThis work evaluated the National Research Council (NRC) dairy model (2001) predictions of rumen undegradable (RUP) and degradable (RDP) protein compared with measured postruminal non-ammonia, nonmicrobial (NANMN) and microbial N flows. Models were evaluated using the root mean squared prediction error (RMSPE) as a percent of the observed mean; mean and slope biases as percentages of mean squared prediction error (MSPE), and concordance correlation coefficient, (CCC). The NRC (2001) over-estimated NANMN by 18% and under-estimated microbial N by 14%. Both responses had large mean biases (19% and 20% of MSPE, respectively); and NANMN had a slope Dias (22% of MSPE). The NRC NANMN estimate had high RMSPE (46% of observed mean) and low CCC (0.37); updating feed library A, B, and C protein fractions and degradation rate (K-d) estimates with newer literature only marginally improved fit. The re-fit NRC models for NANMN and microbial N had CCC of 0.89 and 0.94, respectively. When compared with a prediction of NANMN as a static mean fraction of N intake; the re-derived NRC approach did not have improved fit. A protein system of intermediate complexity was derived in an attempt to estimate NANMN with improved fit compared with the static mean NANMN model. In this system, postruminal appearance of A, B, and C protein fractions were predicted in a feed-type specific mariner rather than from estimated passage and degradation rates. In a comparison to independent data. achieved through cross-validation; the new protein system improved RMSPE (34 vs. 36% of observed mean) and CCC (0.42 vs. 0.30) compared with the static mean NANMN model. When the NRC microbial N equation was re-derived, the RDP term dropped from the model. Consequently, 2 new microbial protein equations were formulated, both used a saturating (increasing at a decreasing rate) form: one saturated with respect to TDN and the other saturated over increasing intakes of rumen degraded starch and NDF. Both equations expressed maximal microbial N production as a linear function of RDP intake. The function relating microbial N to intake of rumen degradable carbohydrate improved RMSPE (24 vs. 28% of the observed mean) and CCC (0.63 vs 0.30) compared with the re-derived NRC model. The newly derived equations showed modest improvements in model fit and improved capacity to account for known biological effects; however, substantial variability in NANMN and microbial N estimates remained unexplained.en
dc.description.notesIn addition to the funding sources listed in the title page footnote, funding for this project was provided by Agricultural and Food Research Initiative Competitive Grant no. 2011-68004-30340 and no. 2015-03656 from the USDA National Institute of Food and Agriculture (Washington, DC) and by Papillon (Easton, MD). The authors acknowledge the contributions of the late L. F. Reutzel (Laud O'Lakes/Purina Mills) to portions of the initial code used in the project and the late Gale Bateman (Akey, Lewisburg, OH) for help in assembling and collating the dietary ingredient data.en
dc.description.sponsorshipAgricultural and Food Research Initiative Competitive Grant [2011-68004-30340]; USDA National Institute of Food and Agriculture (Washington, DC) [2015-03656]; Papillon (Easton, MD)en
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.3168/jds.2015-10801en
dc.identifier.eissn1525-3198en
dc.identifier.issn0022-0302en
dc.identifier.issue5en
dc.identifier.pmid28259406en
dc.identifier.urihttp://hdl.handle.net/10919/94379en
dc.identifier.volume100en
dc.language.isoenen
dc.rightsCreative Commons Attribution-NonCommercial-NoDerivatives 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by-nc-nd/4.0/en
dc.subjectNational Research Council (2001) dairy modelen
dc.subjectduodenal flowen
dc.subjectmodel evaluationen
dc.titleEvaluation of the National Research Council (2001) dairy model and derivation of new prediction equations. 2. Rumen degradable and undegradable proteinen
dc.title.serialJournal of Dairy Scienceen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.dcmitypeStillImageen

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