Evaluation of the National Research Council (2001) dairy model and derivation of new prediction equations. 1. Digestibility of fiber, fat, protein, and nonfiber carbohydrate

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dc.contributor.authorWhite, Robin R.en
dc.contributor.authorRoman-Garcia, Y.en
dc.contributor.authorFirkins, J. L.en
dc.contributor.authorVandeHaar, M. J.en
dc.contributor.authorArmentano, L. E.en
dc.contributor.authorWeiss, W. P.en
dc.contributor.authorMcGill, Tyler R.en
dc.contributor.authorGarnett, R.en
dc.contributor.authorHanigan, Mark D.en
dc.contributor.departmentDairy Scienceen
dc.date.accessioned2019-10-04T17:40:07Zen
dc.date.available2019-10-04T17:40:07Zen
dc.date.issued2017-05en
dc.description.abstractEvaluation of ration balancing systems such as the National Research Council (NRC) Nutrient Requirements series is important for improving predictions of animal nutrient requirements and advancing feeding strategies. This work used a. literature data set (n = 550) to evaluate predictions of total-tract digested neutral detergent fiber (NDF), fatty acid (FA), crude protein (CP), and nonfiber carbohydrate (NFC) estimated by the NRC (2001) dairy model. Mean biases suggested that the NRC (2001) lactating cow model overestimated true FA and CP digestibility by 26 and 7%, respectively, and under-predicted NDF digestibility by 16%. All NR,C (2001) estimates had notable mean and slope biases and large root mean squared prediction error (RMSPE), and concordance (CCC) ranged from poor to good. Predicting NDF digestibility with independent equations for legumes, corn silage, other forages, and nonforage feeds improved CCC (0.85 vs. 0.76) compared with the re-derived NRC (2001) equation form (NRC equation with parameter estimates re-derived against this data set). Separate FA digestion coefficients were derived for different fat supplements (animal fats, oils. and other fat types) and for the basal diet. This equation returned improved (from 0.76 to 0.94) CCC compared with the re-derived NRC (2001) equation form. Unique CP digestibility equations were derived for forages, animal protein feeds, plant protein feeds, and other feeds, which improved CCC compared with the re-derived NRC (2001) equation form (0.74 to 0.85). New NFC digestibility coefficients were derived for grain-specific starch digestibilities, with residual organic matter assumed to be 98% digestible. A Monte Carlo cross-validation was performed to evaluate repeatability of model fit. In this procedure, data were randomly subsetted 500 tunes into derivation (60%) and evaluation (40%) data sets, and equations were derived using the derivation data and then evaluated against the independent evaluation data. Models derived with random study effects demonstrated poor repeatability of fit in independent evaluation. Similar equations derived without random study effects showed improved fit against independent data, and little evidence of biased parameter estimates associated with failure to include study effects. The equations derived in this analysis provide interesting insight, into how NDF, starch, FA, and CP digestibilities are affected by intake, feed type, and diet composition.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 (Land 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.2015-10800en
dc.identifier.eissn1525-3198en
dc.identifier.issn0022-0302en
dc.identifier.issue5en
dc.identifier.pmid28259403en
dc.identifier.urihttp://hdl.handle.net/10919/94358en
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.subjecttotal-tract digestibilityen
dc.subjectmodel evaluationen
dc.titleEvaluation of the National Research Council (2001) dairy model and derivation of new prediction equations. 1. Digestibility of fiber, fat, protein, and nonfiber carbohydrateen
dc.title.serialJournal of Dairy Scienceen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten
dc.type.dcmitypeStillImageen
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