{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,8,13]],"date-time":"2026-08-13T14:31:00Z","timestamp":1786631460161,"version":"build-2736575974"},"reference-count":69,"publisher":"Frontiers Media SA","license":[{"start":{"date-parts":[[2025,10,6]],"date-time":"2025-10-06T00:00:00Z","timestamp":1759708800000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"content-domain":{"domain":["frontiersin.org"],"crossmark-restriction":true},"short-container-title":["Front. Microbiol."],"abstract":"<jats:sec><jats:title>Introduction<\/jats:title><jats:p>This study aimed to evaluate the effects of sources of non-protein nitrogen (NPN) or rumen undegradable protein (RUP) as supplements on intake, nutrient digestibility, fermentation parameters, and ruminal microbiota in Nellore steers grazing during the dry season.<\/jats:p><\/jats:sec><jats:sec><jats:title>Methods<\/jats:title><jats:p>The experiment was conducted during the dry season from September to October 2018, in a grazing area of <jats:italic>Urochloa brizantha (A. Rich.) Stapf.<\/jats:italic> cv. <jats:italic>Xara\u00e9s.<\/jats:italic> Eight rumen-and duodenum-cannulated Nellore steers were used in a 4 \u00d7 4 Latin square design (2 treatments and 2 periods) balanced for residual effects. The treatments included (1) mineral salt with urea (SMU), formulated to meet 50% of the steer RDP requirement as NPN; and (2) supplementation with corn gluten meal (GLU; 0.3% of body weight) as a source of RUP, with added mineral salt.<\/jats:p><\/jats:sec><jats:sec><jats:title>Results<\/jats:title><jats:p>GLU supplementation significantly increased supplement intake (<jats:italic>p<\/jats:italic> &amp;lt; 0.05) and tended to decrease the intake of forage NDF. Although GLU supplementation improved NDF digestibility, no significant differences were observed in the digestibility of DM, OM, or CP between the treatments (<jats:italic>p<\/jats:italic> &amp;gt; 0.05). GLU supplementation significantly increased the relative abundance of several genera, including <jats:italic>Ruminococcus 1<\/jats:italic>, <jats:italic>Ruminococcus 2<\/jats:italic>, <jats:italic>Erysipelotrichaceae UCG-004<\/jats:italic>, <jats:italic>Thermoplasmatales Incertae Sedis<\/jats:italic>, <jats:italic>Lachnospiraceae XPB1014<\/jats:italic>, <jats:italic>Anaeroplasma<\/jats:italic> spp., <jats:italic>Anaerotruncus<\/jats:italic> spp. and <jats:italic>Eubacterium ruminantium<\/jats:italic> (<jats:italic>p<\/jats:italic> &amp;lt; 0.05). The PCA biplot revealed positive associations between GLU supplementation and greater ruminal abundance of <jats:italic>Prevotellaceae UCG-004<\/jats:italic> and Bacteroidetes, as well as with higher concentrations of butyrate, propionate, and valerate acids.<\/jats:p><\/jats:sec><jats:sec><jats:title>Discussion<\/jats:title><jats:p>Supplementation with GLU as a source of RUP in grazing steers during the dry season modulated the rumen microbiota by increasing the abundance of key fibrolytic bacteria and improved fiber digestibility.<\/jats:p><\/jats:sec>","DOI":"10.3389\/fmicb.2025.1670636","type":"journal-article","created":{"date-parts":[[2025,10,6]],"date-time":"2025-10-06T14:59:18Z","timestamp":1759762758000},"update-policy":"https:\/\/doi.org\/10.3389\/crossmark-policy","source":"Crossref","is-referenced-by-count":4,"title":["Assessing the impact of non-protein nitrogen or rumen undegradable protein supplementation on rumen bacterial diversity and ruminal fermentation in grazing steers during the dry season"],"prefix":"10.3389","volume":"16","author":[{"given":"Ana Veronica Lino","family":"Dias","sequence":"first","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yury Tatiana","family":"Granja-Salcedo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Juliana Duarte","family":"Messana","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Karine Dalla Vecchia","family":"Camargo","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"K\u00eania Larissa Gomes Carvalho","family":"Alves","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Elisabeth Vict\u00f3ria Alves","family":"Machado","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Milena Tavares Lima","family":"Constancio","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ricardo Andrade","family":"Reis","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Telma Teresinha","family":"Berchielli","sequence":"additional","affiliation":[],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1965","published-online":{"date-parts":[[2025,10,6]]},"reference":[{"key":"ref1","first-page":"103","article-title":"Influence of delignifying agents on tissue structure in bermudagrass stems","volume":"6","author":"Akin","year":"1987","journal-title":"Food Microstruct."},{"key":"ref2","doi-asserted-by":"publisher","first-page":"3063","DOI":"10.2527\/1996.74123063x","article-title":"Physical constraints on voluntary intake of forages by ruminants","volume":"74","author":"Allen","year":"1996","journal-title":"J. Anim. Sci."},{"key":"ref3","doi-asserted-by":"publisher","first-page":"102316","DOI":"10.1016\/j.anaerobe.2020.102316","article-title":"Rumen bacterial diversity in relation to nitrogen retention in beef cattle","volume":"66","author":"Alves","year":"2020","journal-title":"Anaerobe"},{"key":"ref4","volume-title":"Official methods of analysis of the Association of the Analytical Chemists","year":"1995"},{"key":"ref5","volume-title":"Official methods of analysis of AOAC international","year":"2005"},{"key":"ref6","volume-title":"The nutrient requirements of ruminant livestock","year":"1984"},{"key":"ref7","doi-asserted-by":"publisher","first-page":"E9","DOI":"10.3168\/jds.S0022-0302(05)73133-7","article-title":"Nitrogen metabolism in the rumen","volume":"88","author":"Bach","year":"2005","journal-title":"J. Dairy Sci."},{"key":"ref8","first-page":"29","article-title":"Experimental techniques: the HFRO sward stick","volume":"20","author":"Barthram","year":"1985","journal-title":"Bienn. Rep. HFRO."},{"key":"ref9","doi-asserted-by":"publisher","first-page":"201","DOI":"10.2527\/jas.2015-9493","article-title":"Effects of varying ruminally undegradable protein supplementation on forage digestion, nitrogen metabolism, and urea kinetics in Nellore cattle fed low-quality tropical forage","volume":"94","author":"Batista","year":"2016","journal-title":"J. Anim. Sci."},{"key":"ref10","doi-asserted-by":"publisher","first-page":"44","DOI":"10.1017\/S1751731115001512","article-title":"Effect of protein supplementation on ruminal parameters and microbial community fingerprint of Nellore steers fed tropical forages","volume":"10","author":"Bento","year":"2016","journal-title":"Animal"},{"key":"ref11","doi-asserted-by":"publisher","first-page":"90","DOI":"10.1186\/s40168-018-0470-z","article-title":"Optimizing taxonomic classification of marker-gene amplicon sequences with QIIME 2\u2019s q2-feature-classifier plugin","volume":"6","author":"Bokulich","year":"2018","journal-title":"Microbiome."},{"key":"ref12","doi-asserted-by":"publisher","first-page":"852","DOI":"10.1038\/s41587-019-0209-9","article-title":"Reproducible, interactive, scalable and extensible microbiome data science using QIIME 2","volume":"37","author":"Bolyen","year":"2019","journal-title":"Nat. Biotechnol."},{"key":"ref13","doi-asserted-by":"publisher","first-page":"2729","DOI":"10.2527\/jas.2009-2641","article-title":"Effect of nitrogen supplementation on urea kinetics and microbial use of recycled urea in steers consuming corn-based diets","volume":"88","author":"Brake","year":"2010","journal-title":"J. Anim. Sci."},{"key":"ref14","first-page":"19","article-title":"Breve hist\u00f3rico das rela\u00e7\u00f5es entre anatomia vegetal e qualidade de gram\u00edneas forrageiras com \u00eanfase para o g\u00eanero Brachiaria","volume":"76","author":"Brito","year":"2001","journal-title":"Rev. Agric."},{"key":"ref15","doi-asserted-by":"publisher","first-page":"4985","DOI":"10.2527\/jas.2011-4107","article-title":"Rumen degradable protein supply affects microbial efficiency in continuous culture and growth in steers","volume":"90","author":"Brooks","year":"2012","journal-title":"J. Anim. Sci."},{"key":"ref16","doi-asserted-by":"publisher","first-page":"581","DOI":"10.1038\/nmeth.3869","article-title":"DADA2: high-resolution sample inference from Illumina amplicon data","volume":"13","author":"Callahan","year":"2016","journal-title":"Nat. Methods"},{"key":"ref17","doi-asserted-by":"publisher","first-page":"115258","DOI":"10.1016\/j.anifeedsci.2022.115258","article-title":"Intake, metabolism parameters, and performance of growing beef cattle on pasture supplemented with different rumen undegradable protein with different amino acid profile","volume":"286","author":"Camargo","year":"2022","journal-title":"Anim. Feed Sci. Technol."},{"key":"ref18","doi-asserted-by":"publisher","first-page":"4516","DOI":"10.1073\/pnas.1000080107","article-title":"Global patterns of 16S rRNA diversity at a depth of millions of sequences per sample","author":"Caporaso","year":"2011","journal-title":"Proc. Natl. Acad. Sci. USA"},{"key":"ref19","volume-title":"Estimation of microbial protein supply to sheep and cattle based on urinary excretion of purine derivatives: An overview of the technical details","author":"Chen","year":"1992"},{"key":"ref20","doi-asserted-by":"publisher","first-page":"553","DOI":"10.1079\/BJN19790147","article-title":"The mechanism of passage of endogenous urea through the rumen wall and the role of ureolytic epithelial bacteria in the urea flux","volume":"42","author":"Cheng","year":"1979","journal-title":"Br. J. Nutr."},{"key":"ref21","doi-asserted-by":"publisher","first-page":"2304","DOI":"10.3168\/jds.S0022-0302(92)77992-2","article-title":"Microbial protein synthesis and flows of nitrogen fractions to the duodenum of dairy cows","volume":"75","author":"Clark","year":"1992","journal-title":"J. Dairy Sci."},{"key":"ref22","doi-asserted-by":"publisher","first-page":"2242","DOI":"10.1071\/AN16609","article-title":"The effects of partial substitution of soybean with urea or slow-release urea on finishing performance, meat quality, and digestion parameters of Nellore steers","volume":"58","author":"Corte","year":"2018","journal-title":"Anim. Prod. Sci."},{"key":"ref23","doi-asserted-by":"publisher","first-page":"736","DOI":"10.1128\/JB.01559-07","article-title":"Niche-specific features of the intestinal Bacteroidales","volume":"190","author":"Coyne","year":"2008","journal-title":"J. Bacteriol."},{"key":"ref24","doi-asserted-by":"publisher","first-page":"136","DOI":"10.1016\/j.livsci.2009.06.013","article-title":"Parameterization of ruminal fibre degradation in low-quality tropical forage using Michaelis\u2013Menten kinetics","volume":"126","author":"Detmann","year":"2009","journal-title":"Livest. Sci."},{"key":"ref25","first-page":"191","article-title":"Optimizing the use of basal forage resources","author":"Detmann","year":"2010"},{"key":"ref26","doi-asserted-by":"publisher","first-page":"1622","DOI":"10.3390\/life13081622","article-title":"Efficiency of amino acid utilization in Nellore cattle grazing low-quality forage supplemented with different sources of nitrogen","volume":"13","author":"Dias","year":"2023","journal-title":"Life"},{"key":"ref27","doi-asserted-by":"publisher","first-page":"3298","DOI":"10.3168\/jds.S0022-0302(97)76305-7","article-title":"Effect of processing high moisture ear corn on ruminal fermentation and milk yield","volume":"80","author":"Ekinci","year":"1997","journal-title":"J. Dairy Sci."},{"key":"ref28","doi-asserted-by":"publisher","first-page":"4269","DOI":"10.1007\/s00253-017-8150-7","article-title":"Fermentation of model hemicelluloses by Prevotella strains and Butyrivibrio fibrisolvens in pure culture and in ruminal enrichment cultures","volume":"101","author":"Emerson","year":"2017","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref29","doi-asserted-by":"publisher","first-page":"1","DOI":"10.1016\/0006-3207(92)91201-3","article-title":"Conservation evaluation and phylogenetic diversity","volume":"61","author":"Faith","year":"1992","journal-title":"Biol. Conserv."},{"key":"ref30","doi-asserted-by":"publisher","first-page":"249","DOI":"10.3168\/jds.S0022-0302(65)88206-6","article-title":"Method for determining total volatile bases in rumen fluid by steam distillation","volume":"48","author":"Fenner","year":"1965","journal-title":"J. Dairy Sci."},{"key":"ref31","doi-asserted-by":"publisher","first-page":"466","DOI":"10.15232\/aas.2024-02537","article-title":"Invited review: role for isoacids in dairy nutrition","volume":"40","author":"Firkins","year":"2024","journal-title":"Appl. Anim. Sci."},{"key":"ref32","doi-asserted-by":"publisher","first-page":"E1","DOI":"10.3168\/jds.2006-518","article-title":"Ruminal nitrogen metabolism: perspectives for integration of microbiology and nutrition for dairy","volume":"90","author":"Firkins","year":"2007","journal-title":"J. Dairy Sci."},{"key":"ref33","doi-asserted-by":"publisher","first-page":"121","DOI":"10.1038\/nrmicro1817","article-title":"Polysaccharide utilization by gut bacteria: potential for new insights from genomic analysis","volume":"6","author":"Flint","year":"2008","journal-title":"Nat. Rev. Microbiol."},{"key":"ref34","doi-asserted-by":"publisher","first-page":"797","DOI":"10.5713\/ajas.16.0629","article-title":"Intake, digestibility, and rumen and metabolic characteristics of cattle fed low-quality tropical forage and supplemented with nitrogen and different levels of starch","volume":"30","author":"Franco","year":"2017","journal-title":"Asian Australas. J. Anim. Sci."},{"key":"ref35","doi-asserted-by":"publisher","first-page":"e0176701","DOI":"10.1371\/journal.pone.0176701","article-title":"Studies on bacterial community composition are affected by the time and storage method of the rumen content","volume":"12","author":"Granja-Salcedo","year":"2017","journal-title":"PLoS One"},{"key":"ref36","doi-asserted-by":"publisher","first-page":"465","DOI":"10.3389\/fmicb.2015.00465","article-title":"Maximizing efficiency of rumen microbial protein production","volume":"6","author":"Hackmann","year":"2015","journal-title":"Front. Microbiol."},{"key":"ref37","doi-asserted-by":"publisher","first-page":"269","DOI":"10.2307\/3893931","article-title":"The approximation of cattle diet through herbage sampling","volume":"7","author":"Halls","year":"1954","journal-title":"J. Range Manag."},{"key":"ref38","doi-asserted-by":"publisher","first-page":"6338","DOI":"10.1128\/AEM.01052-10","article-title":"Correlation of particular bacterial PCR-denaturing gradient gel electrophoresis patterns with bovine ruminal fermentation parameters and feed efficiency traits","volume":"76","author":"Hernandez-Sanabria","year":"2010","journal-title":"Appl. Environ. Microbiol."},{"key":"ref39","doi-asserted-by":"publisher","first-page":"1325","DOI":"10.1007\/s00253-022-11775-8","article-title":"Comparative analysis of gut microbial composition and potential functions in captive forest and alpine musk deer","volume":"106","author":"Jiang","year":"2022","journal-title":"Appl. Microbiol. Biotechnol."},{"key":"ref40","doi-asserted-by":"crossref","DOI":"10.1007\/978-3-642-38954-2_384","article-title":"The phylum Synergistetes","volume-title":"The prokaryotes","author":"Jumas-Bilak","year":"2014"},{"key":"ref41","doi-asserted-by":"publisher","first-page":"131","DOI":"10.5713\/ajas.2009.r.01","article-title":"Fibrolytic rumen bacteria: their ecology and functions","volume":"22","author":"Koike","year":"2009","journal-title":"Anim. Biosci."},{"key":"ref42","doi-asserted-by":"publisher","first-page":"814","DOI":"10.1038\/nbt.2676","article-title":"Predictive functional profiling of microbial communities using 16S rRNA marker gene sequences","volume":"31","author":"Langille","year":"2013","journal-title":"Nat. Biotechnol."},{"key":"ref43","article-title":"Anatomia de plantas forrageiras","volume-title":"Forragicultura: ci\u00eancia, tecnologia e gest\u00e3o dos recursos forrageiros","author":"Lempp","year":"2013"},{"key":"ref44","doi-asserted-by":"crossref","first-page":"277","DOI":"10.1079\/NRR19900016","article-title":"Factors affecting the utilization of quality forages by ruminants particularly under tropical conditions","volume":"3","author":"Leng","year":"1990","journal-title":"Nutr. Res. Rev."},{"key":"ref45","doi-asserted-by":"publisher","first-page":"347","DOI":"10.1016\/0377-8401(95)00837-3","article-title":"Standardization of procedures for nitrogen fractionation of ruminant feeds","volume":"57","author":"Licitra","year":"1996","journal-title":"Anim. Feed Sci. Technol."},{"key":"ref46","doi-asserted-by":"publisher","first-page":"8228","DOI":"10.1128\/AEM.71.12.8228-8235.2005","article-title":"UniFrac: a new phylogenetic method for comparing microbial communities","volume":"71","author":"Lozupone","year":"2005","journal-title":"Appl. Environ. Microbiol."},{"key":"ref47","doi-asserted-by":"publisher","first-page":"1981","DOI":"10.3389\/fmicb.2020.01981","article-title":"Rumen microbiome composition is altered in sheep divergent in feed efficiency","volume":"11","author":"McLoughlin","year":"2020","journal-title":"Front. Microbiol."},{"key":"ref48","doi-asserted-by":"publisher","first-page":"1550","DOI":"10.1002\/bit.24885","article-title":"Glycans-by-design: engineering bacteria for the biosynthesis of complex glycans and glycoconjugates","volume":"110","author":"Merritt","year":"2013","journal-title":"Biotechnol. Bioeng."},{"key":"ref49","doi-asserted-by":"publisher","first-page":"1217","DOI":"10.1093\/jaoac\/85.6.1217","article-title":"Gravimetric determination of amylase-treated neutral detergent fibre in feeds with refluxing beakers or crucibles: a collaborative study","volume":"85","author":"Mertens","year":"2002","journal-title":"J. AOAC Int."},{"key":"ref50","first-page":"1380","article-title":"The design, conduct, and interpretation of grazing trials on cultivated and improved pastures","volume":"7","author":"Mott","year":"1952","journal-title":"Proc. Int. Grassl. Congr."},{"key":"ref51","doi-asserted-by":"publisher","first-page":"2070","DOI":"10.3168\/jds.S0022-0302(88)79782-9","article-title":"Protein and energy as an integrated system: relationship of ruminal protein and carbohydrate availability to microbial synthesis and milk production","volume":"71","author":"Nocek","year":"1988","journal-title":"J. Dairy Sci."},{"key":"ref52","doi-asserted-by":"publisher","first-page":"1166","DOI":"10.1017\/S0007114520002251","article-title":"Urea supplementation in rumen and post-rumen for cattle fed a low-quality tropical forage","volume":"124","author":"Oliveira","year":"2020","journal-title":"Br. J. Nutr."},{"key":"ref53","doi-asserted-by":"crossref","first-page":"175","DOI":"10.1079\/9780851993447.0175","article-title":"The in situ technique for the estimation of forage degradability in ruminants","volume-title":"Forage evaluation in ruminant nutrition","author":"\u00d8rskov","year":"2000"},{"key":"ref54","doi-asserted-by":"publisher","first-page":"278","DOI":"10.2527\/1995.731278x","article-title":"Protein and energy utilization by ruminants at pasture","volume":"73","author":"Poppi","year":"1995","journal-title":"J. Anim. Sci."},{"key":"ref55","doi-asserted-by":"publisher","first-page":"560","DOI":"10.1590\/S1516-35982009000300023","article-title":"Rumen dynamics of neutral detergent fiber in cattle fed low-quality tropical forage and supplemented with nitrogenous compounds","volume":"38","author":"Sampaio","year":"2009","journal-title":"Rev. Bras. Zootec."},{"key":"ref56","doi-asserted-by":"publisher","first-page":"85","DOI":"10.1016\/j.livsci.2018.09.016","article-title":"Evaluation of collection days and times to estimate urinary excretion of purine derivatives and nitrogen compounds in grazing Nellore cattle","volume":"217","author":"Silva","year":"2018","journal-title":"Livest. Sci."},{"key":"ref57","doi-asserted-by":"publisher","first-page":"371","DOI":"10.1590\/S1516-35982009001300037","article-title":"Grazing supplementation: availability and quality vs. supplementation levels vs. performance","volume":"38","author":"Silva","year":"2009","journal-title":"Rev. Bras. Zootec."},{"key":"ref58","doi-asserted-by":"publisher","first-page":"807","DOI":"10.1590\/S1516-35982012000300046","article-title":"Creatinine excretion and relationship with body weight of Nellore cattle","volume":"41","author":"Silva","year":"2012","journal-title":"Rev. Bras. Zootec."},{"key":"ref59","doi-asserted-by":"publisher","first-page":"3463","DOI":"10.3390\/ani12243463","article-title":"Effects of post-ruminal urea supplementation during the seasonal period on performance and rumen microbiome of rearing grazing Nellore cattle","volume":"12","author":"Souza","year":"2022","journal-title":"Animals"},{"key":"ref60","doi-asserted-by":"publisher","first-page":"1027","DOI":"10.1038\/nature05414","article-title":"An obesity-associated gut microbiome with increased capacity for energy harvest","volume":"444","author":"Turnbaugh","year":"2006","journal-title":"Nature"},{"key":"ref61","doi-asserted-by":"publisher","first-page":"625","DOI":"10.1002\/jsfa.2740310702","article-title":"Investigation of chromium, cerium and cobalt as markers in digesta. Rate of passage studies","volume":"31","author":"Ud\u00e9n","year":"1980","journal-title":"J. Sci. Food Agric."},{"key":"ref62","doi-asserted-by":"publisher","first-page":"2686","DOI":"10.3168\/jds.s0022-0302(99)75525-6","article-title":"Effect of replacing alfalfa silage with high moisture corn on ruminal protein synthesis estimated from excretion of total purine derivatives","volume":"82","author":"Valadares","year":"1999","journal-title":"J. Dairy Sci."},{"key":"ref63","volume-title":"C\u00e1lculo de exig\u00eancias nutricionais, formula\u00e7\u00e3o de dietas e predi\u00e7\u00e3o de desempenho de zebu\u00ednos puros e cruzados","author":"Valadares Filho","year":"2016"},{"key":"ref64","doi-asserted-by":"publisher","first-page":"666","DOI":"10.1590\/S1516-35982011000300027","article-title":"In situ estimation of indigestible compounds contents in cattle feed and feces using bags made from different textiles","volume":"40","author":"Valente","year":"2011","journal-title":"Rev. Bras. Zootec."},{"key":"ref65","doi-asserted-by":"publisher","first-page":"e288","DOI":"10.1111\/jpn.12604","article-title":"Influence of protein fermentation and carbohydrate source on in vitro methane production","volume":"101","author":"Vanegas","year":"2017","journal-title":"J. Anim. Physiol. Anim. Nutr."},{"key":"ref66","doi-asserted-by":"crossref","first-page":"243","DOI":"10.1017\/S0021859600072610","article-title":"Excretion of purine derivatives by ruminants. Effect of microbial nucleic acid infusion on purine derivative excretion by steers","volume":"114","author":"Verbic","year":"1990","journal-title":"J. Agric. Sci."},{"key":"ref67","doi-asserted-by":"publisher","first-page":"381","DOI":"10.1017\/S002185960001546X","article-title":"The determination of chromic oxide in faeces samples by atomic absorption spectrophotometry","volume":"59","author":"Williams","year":"1962","journal-title":"J. Agric. Sci."},{"key":"ref68","doi-asserted-by":"publisher","first-page":"891898","DOI":"10.3389\/fanim.2022.891898","article-title":"Effects of non-protein nitrogen sources on in vitro rumen fermentation characteristics and microbial diversity","volume":"3","author":"Zhu","year":"2022","journal-title":"Front. Anim. Sci."},{"key":"ref69","doi-asserted-by":"publisher","first-page":"157","DOI":"10.4141\/cjas86-017","article-title":"A rapid procedure for purine measurement and its use for estimating net ruminal protein synthesis","volume":"66","author":"Zinn","year":"1986","journal-title":"Can. J. Anim. 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