{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,10,1]],"date-time":"2026-10-01T01:05:00Z","timestamp":1790816700266,"version":"4.1.0"},"reference-count":89,"publisher":"MDPI AG","issue":"2","license":[{"start":{"date-parts":[[2021,1,29]],"date-time":"2021-01-29T00:00:00Z","timestamp":1611878400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Department of Agriculture, Environment and Rural Affairs","award":["19-1-16"],"award-info":[{"award-number":["19-1-16"]}]},{"name":"John Thompson and Sons Limited","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}]},{"name":"Trouw Nutrition Limited","award":["N\/A"],"award-info":[{"award-number":["N\/A"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>The efficiency with which dairy cows convert dietary nitrogen (N) to milk N is generally low (typically 25%). As a result, much of the N consumed is excreted in manure, from which N can be lost to the environment. Therefore there is increasing pressure to reduce N excretion and improve N use efficiency (NUE) on dairy farms. However, assessing N excretion and NUE on farms is difficult, thus the need to develop proximate measures that can provide accurate estimates of nitrogen utilisation. This review examines a number of these proximate measures. While a strong relationship exists between blood urea N and urinary N excretion, blood sampling is an invasive technique unsuitable for regular herd monitoring. Milk urea N (MUN) can be measured non-invasively, and while strong relationships exist between dietary crude protein and MUN, and MUN and urinary N excretion, the technique has limitations. Direct prediction of NUE using mid-infrared analysis of milk has real potential, while techniques such as near-infrared spectroscopy analysis of faeces and manure have received little attention. Similarly, techniques such as nitrogen isotope analysis, nuclear magnetic resonance spectroscopy of urine, and breath ammonia analysis may all offer potential in the future, but much research is still required.<\/jats:p>","DOI":"10.3390\/ani11020343","type":"journal-article","created":{"date-parts":[[2021,1,29]],"date-time":"2021-01-29T09:25:22Z","timestamp":1611912322000},"page":"343","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":44,"title":["Proxy Measures and Novel Strategies for Estimating Nitrogen Utilisation Efficiency in Dairy Cattle"],"prefix":"10.3390","volume":"11","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-3122-6208","authenticated-orcid":false,"given":"Anna","family":"Lavery","sequence":"first","affiliation":[{"name":"Agri-Food and Biosciences Institute Hillsborough, Large Park, Co. Down, Hillsborough BT26 6DR, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8623-5983","authenticated-orcid":false,"given":"Conrad","family":"Ferris","sequence":"additional","affiliation":[{"name":"Agri-Food and Biosciences Institute Hillsborough, Large Park, Co. Down, Hillsborough BT26 6DR, UK"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2021,1,29]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"199","DOI":"10.1079\/BJN19740073","article-title":"Effect of ammonia concentration on rumen microbial protein production in vitro","volume":"32","author":"Satter","year":"1974","journal-title":"Br. J. Nutr."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"2312","DOI":"10.3168\/jds.S0022-0302(86)80670-1","article-title":"Effect of Rumen Ammonia Concentration on In Situ Rate and Extent of Digestion of Feedstuffs","volume":"69","author":"Erdman","year":"1986","journal-title":"J. Dairy Sci."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"E223","DOI":"10.3168\/jds.S0022-0302(01)70222-6","article-title":"Nitrogen Recycling in the Ruminant: A Review","volume":"84","author":"Lapierre","year":"2001","journal-title":"J. Dairy Sci."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"6298","DOI":"10.3168\/jds.2016-10917","article-title":"Effects of dietary crude protein and rumen-degradable protein concentrations on urea recycling, nitrogen balance, omasal nutrient flow, and milk production in dairy cows","volume":"99","author":"Mutsvangwa","year":"2016","journal-title":"J. Dairy Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"1184","DOI":"10.1017\/S1751731110000911","article-title":"Strategies for optimizing nitrogen use by ruminants","volume":"4","author":"Calsamiglia","year":"2010","journal-title":"Animal"},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"161","DOI":"10.1007\/s10705-017-9893-3","article-title":"Evaluating the potential of dietary crude protein manipulation in reducing ammonia emissions from cattle and pig manure: A meta-analysis","volume":"110","author":"Sajeev","year":"2018","journal-title":"Nutr. Cycl. Agroecosyst."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"3130","DOI":"10.3168\/jds.2010-3681","article-title":"Technical note: Contribution of ammonia emitted from livestock to atmospheric fine particulate matter (PM2.5) in the United States","volume":"94","author":"Hristov","year":"2011","journal-title":"J. Dairy Sci."},{"key":"ref_8","doi-asserted-by":"crossref","first-page":"238","DOI":"10.15232\/aas.2018-01803","article-title":"Invited Review: Emission and mitigation of greenhouse gases from dairy farms: The cow, the manure, and the field","volume":"35","author":"Wattiaux","year":"2019","journal-title":"Appl. Anim. Sci."},{"key":"ref_9","unstructured":"Eggleston, S., Buendia, L., Miwa, K., Ngara, T., and Tanabe, K. (2006). 2006 IPCC Guidelines for National Greenhouse Gas Inventories, Institute for Global Environmental Strategies."},{"key":"ref_10","first-page":"41","article-title":"The continuing challenge of nitrogen loss to the environment: Environmental consequences and mitigation strategies","volume":"2","author":"Stark","year":"2008","journal-title":"Dyn. Soil Dyn. Plant"},{"key":"ref_11","doi-asserted-by":"crossref","unstructured":"Boerema, A., Peeters, A., Swolfs, S., Vandevenne, F., Jacobs, S., Staes, J., and Meire, P. (2016). Soybean Trade: Balancing Environmental and Socio-Economic Impacts of an Intercontinental Market. PLoS ONE, 11.","DOI":"10.1371\/journal.pone.0155222"},{"key":"ref_12","doi-asserted-by":"crossref","first-page":"3182","DOI":"10.3168\/jds.2014-8215","article-title":"Evaluation of between-cow variation in milk urea and rumen ammonia nitrogen concentrations and the association with nitrogen utilization and diet digestibility in lactating cows","volume":"98","author":"Huhtanen","year":"2015","journal-title":"J. Dairy Sci."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1016\/j.agee.2019.04.013","article-title":"Evaluation and prediction of nitrogen use efficiency and outputs in faeces and urine in beef cattle","volume":"280","author":"Angelidis","year":"2019","journal-title":"Agric. Ecosyst. Environ."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"3981","DOI":"10.3168\/jds.S0022-0302(06)72441-9","article-title":"Relationships among Manure Nitrogen Output and Dietary and Animal Factors in Lactating Dairy Cows","volume":"89","author":"Yan","year":"2006","journal-title":"J. Dairy Sci."},{"key":"ref_15","unstructured":"Kebreab, E., Strathe, A.B., Dijkstra, J., Mills, J.A., Reynolds, C.K., and Crompton, L.A. (2010, January 6\u201310). Energy and protein interactions and their effect on nitrogen excretion in dairy cows. Proceedings of the 3rd EAAP International Symposium on Energy and Protein Metabolism, Parma, Italy."},{"key":"ref_16","doi-asserted-by":"crossref","first-page":"1704","DOI":"10.3168\/jds.S0022-0302(06)72238-X","article-title":"Effect of Dietary Crude Protein Concentration on Milk Production and Nitrogen Utilization in Lactating Dairy Cows","volume":"89","author":"Colmenero","year":"2006","journal-title":"J. Dairy Sci."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"217","DOI":"10.1016\/j.envsci.2010.03.007","article-title":"Nitrogen use efficiency: A potential performance indicator and policy tool for dairy farms","volume":"13","author":"Powell","year":"2010","journal-title":"Environ. Sci. Policy"},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"2964","DOI":"10.3168\/jds.S0022-0302(97)76262-3","article-title":"A Statistical Evaluation of Animal and Nutritional Factors Influencing Concentrations of Milk Urea Nitrogen","volume":"80","author":"Broderick","year":"1997","journal-title":"J. Dairy Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"879","DOI":"10.2527\/2005.834879x","article-title":"Using blood urea nitrogen to predict nitrogen excretion and efficiency of nitrogen utilization in cattle, sheep, goats, horses, pigs, and rats1","volume":"83","author":"Kohn","year":"2005","journal-title":"J. Anim. Sci."},{"key":"ref_20","doi-asserted-by":"crossref","first-page":"2284","DOI":"10.3168\/jds.S0022-0302(01)74675-9","article-title":"The Relationship of Milk Urea Nitrogen to Urine Nitrogen Excretion in Holstein and Jersey Cows","volume":"84","author":"Kauffman","year":"2001","journal-title":"J. Dairy Sci."},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"407","DOI":"10.1017\/S0021859612000561","article-title":"A review of factors influencing milk urea concentration and its relationship with urinary urea excretion in lactating dairy cattle","volume":"151","author":"Spek","year":"2013","journal-title":"J. Agric. Sci."},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"R418","DOI":"10.1152\/ajpregu.2001.280.2.R418","article-title":"Effect of water restriction on feeding and metabolism in dairy cows","volume":"280","author":"Burgos","year":"2001","journal-title":"Am. J. Physiol. Integr. Comp. Physiol."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"117","DOI":"10.1016\/j.livprodsci.2004.03.005","article-title":"Investigations on the water intake of lactating dairy cows","volume":"90","author":"Meyer","year":"2004","journal-title":"Livest. Prod. Sci."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"655","DOI":"10.1136\/vr.159.20.655","article-title":"Use of metabolic profiles for the assessment of dietary adequacy in UK dairy herds","volume":"159","author":"Macrae","year":"2006","journal-title":"Veter- Rec."},{"key":"ref_25","doi-asserted-by":"crossref","unstructured":"Andrews, A.H., Blowey, R.W., Boyd, H., and Eddy, R.G. (2004). Metabolic profiles. Bovine Medicine: Diseases and Husbandry of Cattle, Blackwell Science.","DOI":"10.1002\/9780470752401"},{"key":"ref_26","doi-asserted-by":"crossref","first-page":"1001","DOI":"10.3168\/jds.2008-1155","article-title":"Effect of dietary protein content on animal production and blood metabolites of dairy cows during lactation","volume":"92","author":"Law","year":"2009","journal-title":"J. Dairy Sci."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"1159","DOI":"10.5713\/ajas.2008.70734","article-title":"Evaluation of Urinary Nitrogen Excretion from Plasma Urea Nitrogen in Dry and Lactating Cows","volume":"21","author":"Kume","year":"2008","journal-title":"Asian-Australas. J. Anim. Sci."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"5499","DOI":"10.3168\/jds.2007-0299","article-title":"Prediction of Ammonia Emission from Dairy Cattle Manure Based on Milk Urea Nitrogen: Relation of Milk Urea Nitrogen to Urine Urea Nitrogen Excretion","volume":"90","author":"Burgos","year":"2007","journal-title":"J. Dairy Sci."},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"1747","DOI":"10.3168\/jds.2018-15103","article-title":"Metabolic profiling of early-lactation dairy cows using milk mid-infrared spectra","volume":"102","author":"Luke","year":"2019","journal-title":"J. Dairy Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"11298","DOI":"10.3168\/jds.2019-16937","article-title":"Prediction of blood metabolites from milk mid-infrared spectra in early-lactation cows","volume":"102","author":"Benedet","year":"2019","journal-title":"J. Dairy Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"227","DOI":"10.3168\/jds.S0022-0302(02)74071-X","article-title":"Evaluation of Models to Estimate Urinary Nitrogen and Expected Milk Urea Nitrogen","volume":"85","author":"Kohn","year":"2002","journal-title":"J. Dairy Sci."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"386","DOI":"10.3168\/jds.S0022-0302(04)73178-1","article-title":"Evaluation of Milk Urea Nitrogen as a Diagnostic of Protein Feeding","volume":"87","author":"Nousiainen","year":"2004","journal-title":"J. Dairy Sci."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"3333","DOI":"10.3168\/jds.S0022-0302(97)76309-4","article-title":"Milk Urea Nitrogen as a Tool to Monitor the Protein Nutrition of Dairy Cows","volume":"80","author":"Hof","year":"1997","journal-title":"J. Dairy Sci."},{"key":"ref_34","first-page":"24","article-title":"Improving nitrogen use efficiency of dairy cows in relation to urea in milk\u2013a review","volume":"34","year":"2016","journal-title":"Anim. Sci. Pap. Rep."},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"7261","DOI":"10.3168\/jds.2012-5582","article-title":"Cow and herd variation in milk urea nitrogen concentrations in lactating dairy cattle","volume":"95","author":"Aguilar","year":"2012","journal-title":"J. Dairy Sci."},{"key":"ref_36","unstructured":"Hendriks, S. (2016). The Effect of Dietary Nitrogen on Nitrogen Partitioning and Milk Production in Grazing Dairy Cows: A Thesis Presented in Partial Fulfilment of the Requirements for the Master of Animal Science at Massey University Palmerston North, New Zealand. [Master\u2019s Thesis, Massey University]."},{"key":"ref_37","doi-asserted-by":"crossref","first-page":"292","DOI":"10.1017\/S1751731113000578","article-title":"Diet effects on urine composition of cattle and N2O emissions","volume":"7","author":"Dijkstra","year":"2013","journal-title":"Animal"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"3219","DOI":"10.2527\/2004.82113219x","article-title":"Effect of dietary crude protein level and degradability on ruminal fermentation and nitrogen utilization in lactating dairy cows1","volume":"82","author":"Hristov","year":"2004","journal-title":"J. Anim. Sci."},{"key":"ref_39","doi-asserted-by":"crossref","first-page":"1651","DOI":"10.1071\/AN14171","article-title":"Nitrogen partitioning, energy use efficiency and isotopic fractionation measurements from cows differing in genetic merit fed low-quality pasture in late lactation","volume":"54","author":"Cheng","year":"2014","journal-title":"Anim. Prod. Sci."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"43","DOI":"10.1017\/S1466252307001156","article-title":"Ammonia and urea transport across the rumen epithelium: A review","volume":"7","author":"Abdoun","year":"2006","journal-title":"Anim. Health Res. Rev."},{"key":"ref_41","doi-asserted-by":"crossref","first-page":"1370","DOI":"10.3168\/jds.S0022-0302(03)73721-7","article-title":"Effects of Varying Dietary Protein and Energy Levels on the Production of Lactating Dairy Cows","volume":"86","author":"Broderick","year":"2003","journal-title":"J. Dairy Sci."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"1848","DOI":"10.3168\/jds.S0022-0302(04)73342-1","article-title":"A Comparison of Instruments and Laboratories Used to Measure Milk Urea Nitrogen in Bulk-Tank Milk Samples","volume":"87","author":"Kohn","year":"2004","journal-title":"J. Dairy Sci."},{"key":"ref_43","doi-asserted-by":"crossref","first-page":"1747","DOI":"10.3168\/jds.S0022-0302(04)73329-9","article-title":"Comparison of Analytical Methods and the Influence of Milk Components on Milk Urea Nitrogen Recovery","volume":"87","author":"Peterson","year":"2004","journal-title":"J. Dairy Sci."},{"key":"ref_44","doi-asserted-by":"crossref","first-page":"2462","DOI":"10.3168\/jds.S0022-0302(03)73840-5","article-title":"Estimation of Genetic Parameters for Concentrations of Milk Urea Nitrogen","volume":"86","author":"Wood","year":"2003","journal-title":"J. Dairy Sci."},{"key":"ref_45","doi-asserted-by":"crossref","first-page":"3529","DOI":"10.3168\/jds.2008-1904","article-title":"Modeling milk urea of Walloon dairy cows in management perspectives","volume":"92","author":"Bastin","year":"2009","journal-title":"J. Dairy Sci."},{"key":"ref_46","doi-asserted-by":"crossref","first-page":"473","DOI":"10.1007\/s13353-013-0159-8","article-title":"Genetic parameters for milk urea concentration and milk traits in Polish Holstein-Friesian cows","volume":"54","author":"Rzewuska","year":"2013","journal-title":"J. Appl. Genet."},{"key":"ref_47","first-page":"56","article-title":"Genetic parameters for milk urea concentration and milk traits in New Zealand grazing dairy cattle","volume":"78","author":"Burke","year":"2018","journal-title":"N. Z. J. Anim. Sci. Prod."},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"2164","DOI":"10.1017\/S1751731119000235","article-title":"Genetic variation in milk urea nitrogen concentration of dairy cattle and its implications for reducing urinary nitrogen excretion","volume":"13","author":"Beatson","year":"2019","journal-title":"Animal"},{"key":"ref_49","doi-asserted-by":"crossref","first-page":"2468","DOI":"10.3168\/jds.2006-487","article-title":"Genetic Analysis of Milk Urea Nitrogen and Lactose and Their Relationships with Other Production Traits in Canadian Holstein Cattle","volume":"90","author":"Miglior","year":"2007","journal-title":"J. Dairy Sci."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"221","DOI":"10.1017\/S1751731115002025","article-title":"Relationship between efficiency of nitrogen utilization and isotopic nitrogen fractionation in dairy cows: Contribution of digestion v. metabolism?","volume":"10","author":"Hijar","year":"2016","journal-title":"Animal"},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"4704","DOI":"10.3168\/jds.2008-1112","article-title":"Lactation Performance of Mid-Lactation Dairy Cows Fed Ruminally Degradable Protein at Concentrations Lower Than National Research Council Recommendations","volume":"91","author":"Cyriac","year":"2008","journal-title":"J. Dairy Sci."},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"2034","DOI":"10.3168\/jds.2008-1777","article-title":"Interactions of energy and predicted metabolizable protein in determining nitrogen efficiency in the lactating dairy cow","volume":"93","author":"McGilliard","year":"2010","journal-title":"J. Dairy Sci."},{"key":"ref_53","unstructured":"Wattiaux, M.A., and Ranathunga, S.D. (2015). Milk Urea Nitrogen as a Tool to Assess Efficiency of Nitrogen Utilization in Dairy Cows, COGECO Expo Center, University of Wisconsin-Madison. Available online: https:\/\/wiagribusiness.org\/fourstatedairy\/2016\/16_Wattiaux.pdf."},{"key":"ref_54","doi-asserted-by":"crossref","first-page":"2681","DOI":"10.3168\/jds.S0022-0302(98)75825-4","article-title":"Using Milk Urea Nitrogen to Predict Nitrogen Excretion and Utilization Efficiency in Lactating Dairy Cows","volume":"81","author":"Jonker","year":"1998","journal-title":"J. Dairy Sci."},{"key":"ref_55","unstructured":"Kohn, R. (2007, January 30\u201331). Use of milk or blood urea nitrogen to identify feed management inefficiencies and estimate nitrogen excretion by dairy cattle and other animals. Proceedings of the Florida Ruminant Nutrition Symposium, Gainesville, FL, USA."},{"key":"ref_56","unstructured":"Ishler, M. (2020, November 02). Interpretation of Milk Urea Nitrogen (MUN) Values. Available online: https:\/\/extension.psu.edu\/interpretation-of-milk-urea-nitrogen-mun-values."},{"key":"ref_57","doi-asserted-by":"crossref","unstructured":"Grelet, C., Froidmont, E., Foldager, L., Salavati, M., Hostens, M., Ferris, C.P., Ingvartsen, K.L., Crowe, M.A., Sorensen, M., and Pierna, J.F. (2020). Potential of milk mid-infrared spectra to predict nitrogen use efficiency of individual dairy cows in early lactation. J. Dairy Sci.","DOI":"10.3168\/jds.2019-17910"},{"key":"ref_58","doi-asserted-by":"crossref","first-page":"53","DOI":"10.1016\/j.anifeedsci.2013.07.003","article-title":"Technical note: Use of near infrared reflectance spectroscopy to assess nitrogen and carbon fractions in dairy cow feces","volume":"185","author":"Althaus","year":"2013","journal-title":"Anim. Feed. Sci. Technol."},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"99","DOI":"10.1017\/S0021859600024175","article-title":"Some observations on the distribution and origin of nitrogen in sheep faeces","volume":"73","author":"Mason","year":"1969","journal-title":"J. Agric. Sci."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"1829","DOI":"10.3168\/jds.S0022-0302(00)75053-3","article-title":"Near-Infrared Spectroscopic Determination of Carbon, Total Nitrogen, and Ammonium-N in Dairy Manures","volume":"83","author":"Reeves","year":"2000","journal-title":"J. Dairy Sci."},{"key":"ref_61","doi-asserted-by":"crossref","first-page":"1911","DOI":"10.13031\/2013.20000","article-title":"Application of Near-Infrared Reflectance Spectroscopy for Determination of Nutrient Contents in Liquid and Solid Manures","volume":"48","author":"Ye","year":"2005","journal-title":"Trans. ASAE"},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"69","DOI":"10.1016\/j.tifs.2012.05.005","article-title":"Authentication of grass-fed beef using bovine muscle, hair or urine","volume":"28","author":"Monahan","year":"2012","journal-title":"Trends Food Sci. Technol."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"12499","DOI":"10.1021\/jf204201f","article-title":"Effect of Dietary Nitrogen Content on the Urine Metabolite Profile of Dairy Cows Assessed by Nuclear Magnetic Resonance (NMR)-Based Metabolomics","volume":"59","author":"Bertram","year":"2011","journal-title":"J. Agric. Food Chem."},{"key":"ref_64","doi-asserted-by":"crossref","unstructured":"Wheadon, N. (2014). Nitrogen isotopic fractionation and nitrogen use efficiency in beef and dairy cattle. [Ph.D. Thesis, Lincoln University].","DOI":"10.1017\/S0007114513004078"},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"2031","DOI":"10.3168\/jds.2010-3763","article-title":"Nitrogen partitioning and isotopic fractionation in dairy cows consuming diets based on a range of contrasting forages","volume":"94","author":"Cheng","year":"2011","journal-title":"J. Dairy Sci."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"74","DOI":"10.3769\/radioisotopes.36.2_74","article-title":"Variations of natural 15N abundances in the tissues and digesta of domestic animals","volume":"36","author":"Sutoh","year":"1987","journal-title":"Radioisot."},{"key":"ref_67","doi-asserted-by":"crossref","first-page":"1158","DOI":"10.1017\/S0007114514004449","article-title":"Diet\u2013animal fractionation of nitrogen stable isotopes reflects the efficiency of nitrogen assimilation in ruminants","volume":"113","author":"Hijar","year":"2015","journal-title":"Br. J. Nutr."},{"key":"ref_68","doi-asserted-by":"crossref","first-page":"1827","DOI":"10.1017\/S1751731117003391","article-title":"Nitrogen isotopic fractionation as a biomarker for nitrogen use efficiency in ruminants: A meta-analysis","volume":"12","author":"Dewhurst","year":"2018","journal-title":"Animal"},{"key":"ref_69","doi-asserted-by":"crossref","first-page":"5785","DOI":"10.2527\/jas.2012-5378","article-title":"Nitrogen isotopic fractionation can be used to predict nitrogen-use efficiency in dairy cows fed temperate pasture","volume":"91","author":"Cheng","year":"2013","journal-title":"J. Anim. Sci."},{"key":"ref_70","doi-asserted-by":"crossref","unstructured":"Nasrollahi, S., Nozi\u00e8re, P., Dewhurst, R., Chantelauze, C., Cheng, L., Froidmont, E., Martin, C., and Cantalapiedra-Hijar, G. (2019). Natural 15N abundances in plasma and urea-N concentration in milk as biomarkers of urinary N excretion in dairy cows: A meta-analysis. Energy and Protein Metabolism and Nutrition, Wageningen Academic Publishers.","DOI":"10.3920\/978-90-8686-891-9_66"},{"key":"ref_71","doi-asserted-by":"crossref","first-page":"771","DOI":"10.1017\/S175173111900226X","article-title":"Effects of hydrolysable tannin-treated grass silage on milk yield and composition, nitrogen partitioning and nitrogen isotopic discrimination in lactating dairy cows","volume":"14","author":"Herremans","year":"2020","journal-title":"Animal"},{"key":"ref_72","doi-asserted-by":"crossref","first-page":"153","DOI":"10.1016\/j.agee.2005.01.015","article-title":"Carbon and nitrogen stable isotope composition of cattle hair: Ecological fingerprints of production systems?","volume":"109","author":"Schwertl","year":"2005","journal-title":"Agric. Ecosyst. Environ."},{"key":"ref_73","doi-asserted-by":"crossref","first-page":"80","DOI":"10.1002\/oa.655","article-title":"Nitrogen isotopes in mammalian herbivores: Hair \u03b415N values from a controlled feeding study","volume":"13","author":"Sponheimer","year":"2003","journal-title":"Int. J. Osteoarchaeol."},{"key":"ref_74","doi-asserted-by":"crossref","first-page":"226","DOI":"10.2527\/1993.711226x","article-title":"The effects of feeding regimen and dietary sucrose supplementation on natural abundance of 15N in some components of ruminal fluid and plasma of sheep1","volume":"71","author":"Sutoh","year":"1993","journal-title":"J. Anim. Sci."},{"key":"ref_75","doi-asserted-by":"crossref","first-page":"2945","DOI":"10.1093\/ndt\/gfr738","article-title":"Real-time monitoring of breath ammonia during haemodialysis: Use of ion mobility spectrometry (IMS) and cavity ring-down spectroscopy (CRDS) techniques","volume":"27","author":"Neri","year":"2012","journal-title":"Nephrol. Dial. Transplant."},{"key":"ref_76","doi-asserted-by":"crossref","first-page":"97","DOI":"10.1016\/j.livsci.2018.10.010","article-title":"Breath ammonia as a bioindicator of protein nutrition in heifers","volume":"218","author":"Valente","year":"2018","journal-title":"Livest. Sci."},{"key":"ref_77","doi-asserted-by":"crossref","first-page":"1438","DOI":"10.3168\/jds.S0022-0302(01)70176-2","article-title":"Assessment of Rumen Processes by Selected-Ion-Flow-Tube Mass Spectrometric Analysis of Rumen Gases","volume":"84","author":"Dewhurst","year":"2001","journal-title":"J. Dairy Sci."},{"key":"ref_78","doi-asserted-by":"crossref","first-page":"4310","DOI":"10.3168\/jds.2012-6265","article-title":"Prediction of urinary nitrogen and urinary urea nitrogen excretion by lactating dairy cattle in northwestern Europe and North America: A meta-analysis","volume":"96","author":"Spek","year":"2013","journal-title":"J. Dairy Sci."},{"key":"ref_79","doi-asserted-by":"crossref","first-page":"5811","DOI":"10.3168\/jds.2018-15829","article-title":"Invited review: Nitrogen in ruminant nutrition: A review of measurement techniques","volume":"102","author":"Hristov","year":"2019","journal-title":"J. Dairy Sci."},{"key":"ref_80","unstructured":"Shirali, M., Hynes, D., and Ferris, C.P. (April, January 30). Using Herd Information and Milk Production Data to Predict Dry Matter Intake Within Feed-to-Yield Concentrate Allocation Strategies. Proceedings of the British Society of Animal science 76th Annual conference: Advances in Animal BioSciences\u2014The Challenge of Change 2020, Brighton, UK."},{"key":"ref_81","doi-asserted-by":"crossref","first-page":"3651","DOI":"10.3168\/jds.2010-3965","article-title":"The use of mid-infrared spectrometry to predict body energy status of Holstein cows","volume":"94","author":"McParland","year":"2011","journal-title":"J. Dairy Sci."},{"key":"ref_82","doi-asserted-by":"crossref","first-page":"253","DOI":"10.3168\/jds.2016-11609","article-title":"Prediction and validation of residual feed intake and dry matter intake in Danish lactating dairy cows using mid-infrared spectroscopy of milk","volume":"100","author":"Shetty","year":"2017","journal-title":"J. Dairy Sci."},{"key":"ref_83","doi-asserted-by":"crossref","first-page":"8907","DOI":"10.3168\/jds.2019-16363","article-title":"Predicting the dry matter intake of grazing dairy cows using infrared reflectance spectroscopy analysis","volume":"102","author":"Lahart","year":"2019","journal-title":"J. Dairy Sci."},{"key":"ref_84","doi-asserted-by":"crossref","first-page":"5411","DOI":"10.3168\/jds.2016-12189","article-title":"The use of mid-infrared spectrometry to estimate the ration composition of lactating dairy cows","volume":"100","author":"Steinwidder","year":"2017","journal-title":"J. Dairy Sci."},{"key":"ref_85","doi-asserted-by":"crossref","first-page":"327","DOI":"10.1017\/S1357729800090184","article-title":"Estimation of dry-matter intake and digestibility in group-fed dairy cows using near infrared reflectance spectroscopy","volume":"79","author":"Garnsworthy","year":"2004","journal-title":"Anim. Sci."},{"key":"ref_86","doi-asserted-by":"crossref","first-page":"220","DOI":"10.1016\/j.anifeedsci.2012.02.005","article-title":"Faecal near-infrared reflectance spectroscopy (NIRS) compared with other techniques for estimating the in vivo digestibility and dry matter intake of lactating grazing dairy cows","volume":"173","author":"Decruyenaere","year":"2012","journal-title":"Anim. Feed. Sci. Technol."},{"key":"ref_87","unstructured":"Nyholm, L., Nousiainen, J., Rinne, M., Ahvenj\u00e4rvi, S., and Huhtanen, P. (2009). Prediction of Digestibility and Intake of Mixed Diets in Dairy Cows from Faecal Samples with Near Infrared Reflectance Spectroscopy (NIRS). Ruminant Physiology: Digestion, Metabolism and Effects of Nutrition on Reproduction and Welfare, Wageningen Academic Publishers."},{"key":"ref_88","doi-asserted-by":"crossref","first-page":"1091","DOI":"10.1071\/CP16383","article-title":"Use of sensor-determined behaviours to develop algorithms for pasture intake by individual grazing cattle","volume":"68","author":"Greenwood","year":"2018","journal-title":"Crop. Pasture Sci."},{"key":"ref_89","doi-asserted-by":"crossref","first-page":"105582","DOI":"10.1016\/j.compag.2020.105582","article-title":"Prediction of bite number and herbage intake by an accelerometer-based system in dairy sheep exposed to different forages during short-term grazing tests","volume":"175","author":"Giovanetti","year":"2020","journal-title":"Comput. Electron. Agric."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/11\/2\/343\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,11]],"date-time":"2025-10-11T05:17:08Z","timestamp":1760159828000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/11\/2\/343"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2021,1,29]]},"references-count":89,"journal-issue":{"issue":"2","published-online":{"date-parts":[[2021,2]]}},"alternative-id":["ani11020343"],"URL":"https:\/\/doi.org\/10.3390\/ani11020343","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2021,1,29]]}}}