{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,8]],"date-time":"2026-09-08T11:40:50Z","timestamp":1788867650289,"version":"build-2803163510"},"reference-count":36,"publisher":"MDPI AG","issue":"16","license":[{"start":{"date-parts":[[2025,8,11]],"date-time":"2025-08-11T00:00:00Z","timestamp":1754870400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Universidad Nacional de Colombia"},{"name":"Instituci\u00f3n Universitaria Aut\u00f3noma de las Am\u00e9ricas"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Animals"],"abstract":"<jats:p>Methane is a potent greenhouse gas (GHG) emitted from several anthropogenic sources, most notably enteric fermentation in domestic ruminants, primarily during exhalation. To date, however, it is unclear whether the excretion route of methane exhaled by ruminants occurs through the mouth or nostrils and what the pattern of excretion is; this is important in designing equipment and methods to measure the methane emitted by ruminants. Thus, the objective of this experiment was to quantify the exhaled methane excreted by dairy cows via the nostrils and mouth while resting, grazing, and ruminating, as well as the pattern of concentration during and between belching. Four tests were conducted in this study with four dairy cows each. In the first test, resting cows, carrying an electronic spirometry mask (ESM) assembled with a methane sensor in its outlet, were used to measure the concentration of methane in the air expelled through the nostrils and to model the methane concentration between belches; in the second test, a mouth mask was used to measure methane excreted through the mouth; in the third test, an ESM with a methane sensor assembled over the mouth was used to measure methane excreted through the mouth; finally, in the fourth test, a methane sensor was manually placed at 2.0\u20133.0 cm in front of the mouth of ruminating cows to measure the methane concentration. In the first test, a pattern of methane concentration between belches was identified, as well as a pattern of the methane concentration and volume of air exhaled during belching. Methane excretion through the mouth was not detected in any of the tests; hence, it is concluded that dairy cows, while resting, ruminating, and grazing, emit enteric methane only through the nostrils under normal respiration conditions. This is important in the respiratory physiology of ruminants and in designing equipment and methodology to measure cranial methane excretion.<\/jats:p>","DOI":"10.3390\/ani15162350","type":"journal-article","created":{"date-parts":[[2025,8,11]],"date-time":"2025-08-11T14:32:36Z","timestamp":1754922756000},"page":"2350","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":5,"title":["Through the Mouth or Nostrils: The Methane Excretion Route in Belching Dairy Cows"],"prefix":"10.3390","volume":"15","author":[{"given":"Ligia Johana","family":"Jaimes","sequence":"first","affiliation":[{"name":"Medicine-Veterinary Facultity, Instituci\u00f3n Universitaria Visi\u00f3n de las Am\u00e9ricas, Medell\u00edn 050031, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Sebasti\u00e1n","family":"Castrill\u00f3n","sequence":"additional","affiliation":[{"name":"Agrarian Sciences Facultity, Universidad Nacional de Colombia, Medell\u00edn 050034, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Brandon Stiven","family":"Bustamante","sequence":"additional","affiliation":[{"name":"Agrarian Sciences Facultity, Universidad Nacional de Colombia, Medell\u00edn 050034, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-7371-4640","authenticated-orcid":false,"given":"H\u00e9ctor Jairo","family":"Correa","sequence":"additional","affiliation":[{"name":"Animal Production Department, Agrarian Sciences Facultity, Universidad Nacional de Colombia, Medell\u00edn 050034, Colombia"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2025,8,11]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"071002","DOI":"10.1088\/1748-9326\/ab9ed2","article-title":"Increasing anthropogenic methane emissions arise equally from agricultural and fossil fuel sources","volume":"15","author":"Jackson","year":"2020","journal-title":"Environ. Res. Lett."},{"key":"ref_2","unstructured":"IDEAM, Fundaci\u00f3n Natura, PNUD, MADS, DNP, and CANCILLER\u00cdA (2022). Informe del Inventario Nacional de Gases Efecto Invernadero 1990\u20132018 Y Carbono Negro 2010\u20132018 de Colombia. Tercer Informe Bienal de Actualizaci\u00f3n de Cambio Clim\u00e1tico, BUR3. Dirigido a la Convenci\u00f3n Marco de las Naciones Unidas Sobre Cambio Clim\u00e1tico."},{"key":"ref_3","unstructured":"Bravo-Parra, A.M. (2021). Cadenas Sostenibles Ante un Clima Cambiante. La Ganader\u00eda en Colombia."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"skac197","DOI":"10.1093\/jas\/skac197","article-title":"Quantification of methane emitted by ruminants: A review of methods","volume":"100","author":"Tedeschi","year":"2022","journal-title":"J. Anim. Sci."},{"key":"ref_5","first-page":"129","article-title":"Recherches chimiques sur la respiration des animaux d\u2019une ferme","volume":"69","author":"Reiset","year":"1863","journal-title":"Ann. Chim. Phys."},{"key":"ref_6","first-page":"228","article-title":"Die Gase des Verdauungsschlauches der Pflanzenfresser","volume":"19","author":"Tappeiner","year":"1883","journal-title":"Z. Biol."},{"key":"ref_7","doi-asserted-by":"crossref","first-page":"1","DOI":"10.1079\/BJN19760053","article-title":"Rates of production of methane in the rumen and large intestine of sheep","volume":"36","author":"Murray","year":"1976","journal-title":"Br. J. Nutr."},{"key":"ref_8","unstructured":"Reynolds, C.K., Crompton, L.A., Barrat, C.B., Donovan, N., and Misselbrook, T. (2013). Arterial, rumen and milk concentration and net absorption of methane into the portal vein of lactating dairy cattle. Adv. Anim. Biosci., 4."},{"key":"ref_9","doi-asserted-by":"crossref","first-page":"492","DOI":"10.3168\/jds.S0022-0302(57)94511-3","article-title":"Technique for Measuring Eructated Gas in Cattle","volume":"40","author":"Colvin","year":"1957","journal-title":"J. Dairy Sci."},{"key":"ref_10","unstructured":"Blaxter, K.L. (1965). Composition and absorption of rumen gases and their importance for the accuracy of respiration trials with tracheostomized ruminants. Energy Metabolism, Academic Press."},{"key":"ref_11","first-page":"213","article-title":"Studies of pharyngeal and laryngeal activity during eructation in ruminants","volume":"23","author":"Dougherty","year":"1962","journal-title":"Am. J. Vet. Res."},{"key":"ref_12","unstructured":"Malone, E. (2019). Large Animal Surgery\u2013Supplemental Notes, University of Minnesota Libraries Publishing."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"38","DOI":"10.3390\/methane1010004","article-title":"Measuring livestock CH4 emissions with the laser methane detector: A Review","volume":"1","author":"Sorg","year":"2021","journal-title":"Methane"},{"key":"ref_14","doi-asserted-by":"crossref","unstructured":"Palangi, V., Taghizadeh, A., Abachi, S., and Lackner, M. (2022). Strategies to mitigate enteric methane emissions in ruminants: A Review. Sustainability, 14.","DOI":"10.3390\/su142013229"},{"key":"ref_15","doi-asserted-by":"crossref","first-page":"102673","DOI":"10.1016\/j.algal.2022.102673","article-title":"Benefits and risks of including the bromoform containing seaweed Asparagopsis in feed for the reduction of methane production from ruminants","volume":"64","author":"Glasson","year":"2022","journal-title":"Algal Res."},{"key":"ref_16","first-page":"83","article-title":"Design and operation of a spirometry mask to quantify exhaled methane emission by grazing cattle","volume":"35","author":"Correa","year":"2023","journal-title":"Livest. Res. Rural. Dev."},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"323","DOI":"10.1016\/j.livsci.2008.09.020","article-title":"Effect of Genotype and Feeding Regime on Enteric Methane, Non-Milk Nitrogen and Performance of Dairy Cows during the Winter Feeding Period","volume":"122","author":"Chagunda","year":"2009","journal-title":"Liv. Sci."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"5239","DOI":"10.2527\/jas.2014-7676","article-title":"Evaluation of the laser methane detector to estimate methane emissions from ewes and steers","volume":"92","author":"Ricci","year":"2014","journal-title":"J. Anim. Sci."},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"285","DOI":"10.1016\/j.compag.2018.08.024","article-title":"Comparison of a laser methane detector with the GreenFeed and two breath analysers for on-farm measurements of methane emissions from dairy cows","volume":"153","author":"Sorg","year":"2018","journal-title":"Comput. Electron. Agric."},{"key":"ref_20","doi-asserted-by":"crossref","unstructured":"Chilliard, Y., Glasser, F., Faulconnier, Y., Bocquier, F., Veissier, I., and Doreau, M. (2009). A new method for simultaneous recording of methane eructation, reticulo-rumen motility and jaw movements in rumen fistulated cattle. Ruminant Physiology: Digestion, Metabolism, and Effects of Nutrition on Reproduction and Welfare, Wageningen Academic Publishers.","DOI":"10.3920\/978-90-8686-683-0"},{"key":"ref_21","doi-asserted-by":"crossref","first-page":"164","DOI":"10.1038\/216164a0","article-title":"Algebraic Model of the Lactation Curve in Cattle","volume":"216","author":"Wood","year":"1967","journal-title":"Nature"},{"key":"ref_22","doi-asserted-by":"crossref","first-page":"3166","DOI":"10.3168\/jds.2011-4605","article-title":"On-farm methane measurements during milking correlate with total methane production by individual dairy cows","volume":"95","author":"Garnsworthy","year":"2012","journal-title":"J. Dairy Sci."},{"key":"ref_23","doi-asserted-by":"crossref","first-page":"e13637","DOI":"10.1111\/asj.13637","article-title":"Prediction of enteric methane emissions from lactating cows using methane to carbon dioxide ratio in the breath","volume":"92","author":"Suzuki","year":"2021","journal-title":"Anim. Sci. J."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"22","DOI":"10.1111\/j.1749-6632.1968.tb19026.x","article-title":"Eructation in ruminants","volume":"150","author":"Dougherty","year":"1968","journal-title":"Ann. N. Y. Acad. Sci."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"459","DOI":"10.1017\/S0021859697004930","article-title":"Rumen gases and bloat in grazing dairy cattle","volume":"129","author":"Moate","year":"1997","journal-title":"J. Agric. Sci."},{"key":"ref_26","unstructured":"Washburn, L.E., and Brody, S. (1937). XLII, Methane, Hydrogen, and Carbon Dioxide Production in the Digestive Tract of Ruminants in Relation to the Respiratory Exchange. Growth and Development with Special Reference to Domestic Animals, University of Missouri, College of Agriculture, Agricultural Experiment Station."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"4121","DOI":"10.3168\/jds.2022-22735","article-title":"Heritability and genetic correlations between enteric methane production and concentration recorded by GreenFeed and sniffers on dairy cows","volume":"106","author":"Aldridge","year":"2023","journal-title":"J. Dairy Sci."},{"key":"ref_28","doi-asserted-by":"crossref","unstructured":"Antanaitis, R., Anskiene, L., Rapaliute, E., Bilskis, R., D\u017eermeikaite, K., Ba\u010d\u0117ninait\u0117, D., Ju\u0161kiene, V., Ju\u0161ka, R., and Me\u0161kinyt\u0117, E. (2022). Relationship between Reticulorumen Parameters Measured in Real Time and Methane Emission and Heat Stress Risk in Dairy Cows. Animals, 12.","DOI":"10.3390\/ani12233257"},{"key":"ref_29","doi-asserted-by":"crossref","first-page":"9512","DOI":"10.3168\/jds.2019-16258","article-title":"Technical note: Interchangeability and comparison of methane measurements in dairy cows with 2 noninvasive infrared systems","volume":"102","author":"Sypniewski","year":"2019","journal-title":"J. Dairy Sci."},{"key":"ref_30","doi-asserted-by":"crossref","first-page":"3394","DOI":"10.3168\/jds.2014-9118","article-title":"Comparison of methods to determine methane emissions from dairy cows in farm conditions","volume":"98","author":"Huhtanen","year":"2015","journal-title":"J. Dairy Sci."},{"key":"ref_31","doi-asserted-by":"crossref","first-page":"1377","DOI":"10.2527\/2005.8361377x","article-title":"Estimates of heat stress relief needs for Holstein dairy cows","volume":"83","author":"Berman","year":"2005","journal-title":"J. Anim. Sci."},{"key":"ref_32","doi-asserted-by":"crossref","first-page":"322","DOI":"10.1016\/S0034-5288(18)31174-3","article-title":"Comparative pulmonary mechanics in the horse and the cow","volume":"46","author":"Gallivan","year":"1989","journal-title":"Res. Vet. Sci."},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"100726","DOI":"10.1016\/j.animal.2023.100726","article-title":"Performance and enteric methane emissions from housed beef cattle fed silage produced on pastures with different forage profiles","volume":"17","author":"Hood","year":"2023","journal-title":"Animal"},{"key":"ref_34","doi-asserted-by":"crossref","unstructured":"Hardan, A., Garnsworthy, P.C., and Bell, M.J. (2021). Detection of methane eructation peaks in dairy cows at a robotic milking station using signal processing. Animals, 12.","DOI":"10.3390\/ani12010026"},{"key":"ref_35","doi-asserted-by":"crossref","first-page":"71","DOI":"10.1016\/0034-5687(90)90007-L","article-title":"The role of carotid bodies in the establishment of oral breathing during nasal obstruction in lambs and ewes","volume":"80","author":"Harding","year":"1990","journal-title":"Respir. Physiol."},{"key":"ref_36","doi-asserted-by":"crossref","first-page":"15","DOI":"10.1093\/af\/vfac035","article-title":"Equine exercise physiology\u2014Challenges to the respiratory system","volume":"12","author":"Mazan","year":"2022","journal-title":"Anim. Front."}],"container-title":["Animals"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2076-2615\/15\/16\/2350\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,10,9]],"date-time":"2025-10-09T18:24:45Z","timestamp":1760034285000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2076-2615\/15\/16\/2350"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,8,11]]},"references-count":36,"journal-issue":{"issue":"16","published-online":{"date-parts":[[2025,8]]}},"alternative-id":["ani15162350"],"URL":"https:\/\/doi.org\/10.3390\/ani15162350","relation":{},"ISSN":["2076-2615"],"issn-type":[{"value":"2076-2615","type":"electronic"}],"subject":[],"published":{"date-parts":[[2025,8,11]]}}}