Models to predict milk fat concentration and yield of lactating dairy cows: A meta-analysis

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dc.contributor.authorDaley, Veridiana L.en
dc.contributor.authorArmentano, L. E.en
dc.contributor.authorHanigan, Mark D.en
dc.date.accessioned2023-05-03T16:52:29Zen
dc.date.available2023-05-03T16:52:29Zen
dc.date.issued2022-10en
dc.description.abstractFew models have attempted to predict total milk fat because of its high variation among and within herds. The objective of this meta-analysis was to develop models to predict milk fat concentration and yield of lactating dairy cows. Data from 158 studies consisting of 658 treatments from 2,843 animals were used. Data from several feed databases were used to calculate dietary nutrients when dietary nutrient composition was not reported. Digested intake (DI, g/d) of each fatty acid (FA; C12:0, C14:0, C16:0, C16:1, C18:0, C18:1 cis, C18:1 trans C18:2, C18:3) and absorbed amounts (g/d) of each AA (Arg, His, Ile, Leu, Lys, Met, Phe, Thr, Trp, Val) were calculated and used as candidate variables in the models. A multi-model inference method was used to fit a large set of mixed models with study as the random effect, and the best models were selected based on Akaike's information criterion corrected for sample size and evaluated further. Observed milk fat concentration (MFC) ranged from 2.26 to 4.78%, and milk fat yield (MFY) ranged from 0.488 to 1.787 kg/d among studies. Dietary levels of forage, starch, and total FA (dry matter basis) averaged 50.8 +/- 10.3% (mean +/- standard deviation), 27.5 +/- 7.0%, and 3.4 +/- 1.3%, respectively. The MFC was positively correlated with dietary forage (0.294) and negatively associated with dietary starch (-0.286). The DI of C18:2 (g/d) was more negatively correlated with MFC (-0.313) than that of the other FA. The best variables for predicting MFC were days in milk, FA-free dry matter intake, forage, starch, DI of C18:2, DI of C18:3, and absorbed Met, His, and Trp. The best predictor variables for MFY were FA-free dry matter intake, days in milk, absorbed Met and Ile, and intakes of digested C16:0 and C18:3. This model had a root mean square error of 14.1% and concordance correlation coefficient of 0.81. Surprisingly, DI of C18:3 was positively related to milk fat, and this relationship was consistently observed among models. The models developed can be used as a practical tool for predicting milk fat of dairy cows, while recognizing that additional factors are likely to also affect fat yield.en
dc.description.notesThis study is part of the activities of the National Animal Nutrition Program (https://animalnutrition.org), a National Research Support Project (NRSP-9). The authors have not stated any conflicts of interest.en
dc.description.sponsorshipNational Research Support Project [NRSP-9]en
dc.description.versionPublished versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.doihttps://doi.org/10.3168/jds.2022-21777en
dc.identifier.eissn1525-3198en
dc.identifier.issue10en
dc.identifier.pmid36055857en
dc.identifier.urihttp://hdl.handle.net/10919/114905en
dc.identifier.volume105en
dc.language.isoenen
dc.publisherElsevieren
dc.rightsCreative Commons Attribution 4.0 Internationalen
dc.rights.urihttp://creativecommons.org/licenses/by/4.0/en
dc.subjectmilk faten
dc.subjectpalmitic aciden
dc.subjectmethionineen
dc.subjectmetaanalysisen
dc.subjectmulti-model inferenceen
dc.titleModels to predict milk fat concentration and yield of lactating dairy cows: A meta-analysisen
dc.title.serialJournal of Dairy Scienceen
dc.typeArticle - Refereeden
dc.type.dcmitypeTexten

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