{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,6,19]],"date-time":"2026-06-19T18:52:57Z","timestamp":1781895177280,"version":"3.54.5"},"reference-count":37,"publisher":"Oxford University Press (OUP)","license":[{"start":{"date-parts":[[2026,5,17]],"date-time":"2026-05-17T00:00:00Z","timestamp":1778976000000},"content-version":"vor","delay-in-days":136,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Grass2Gas"},{"name":"2018 Joint Call of the Cofund ERA-Nets FACCE ERA-GAS","award":["696356"],"award-info":[{"award-number":["696356"]}]},{"name":"ICT-AGRI 2","award":["618123"],"award-info":[{"award-number":["618123"]}]},{"name":"SusAn","award":["696231"],"award-info":[{"award-number":["696231"]}]},{"DOI":"10.13039\/501100005416","name":"The Research Council of Norway","doi-asserted-by":"publisher","award":["309158"],"award-info":[{"award-number":["309158"]}],"id":[{"id":"10.13039\/501100005416","id-type":"DOI","asserted-by":"publisher"}]},{"name":"Green ERA-Hub"},{"name":"Coordination and Support Action"},{"name":"European Union\u2019s Horizon Europe research and innovation","award":["101056828"],"award-info":[{"award-number":["101056828"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":[],"published-print":{"date-parts":[[2026,1,8]]},"abstract":"<jats:title>Abstract<\/jats:title>\n                  <jats:p>Accurate measurement of dry matter intake (DMI) in sheep is logistically challenging and costly, particularly under commercial conditions and across diverse production systems. This study evaluated whether methane (CH4), carbon dioxide (CO2) and oxygen (O2) gas measurements from portable accumulation chambers (PAC), combined with bodyweight (BW) and eating time (ET), can predict DMI in gestating ewes. Two indoor feeding trials were conducted at a single research facility using Norwegian White Sheep (NWS) and Old Norwegian Spaelsau (ONS). Trial 1 used two grass silage qualities in a 2\u2009\u00d7\u20092 factorial design; Trial 2 used fresh-cut herbage in a repeated-measures design. Ewes (n\u2009=\u200940 per trial; 29 in common) were individually housed with access to one feed bin and fed ad libitum. Daily DMI was recorded using automated feed bins, and PAC measurements of CH4, CO2, and O2 were collected on 20 d per ewe per trial. After quality control, 1,830 ewe d records remained. Supervised learning models were trained on ewe-identity\u2013blocked training sets and evaluated on external test sets stratified by trial and breed. In this particular dataset, random forest (RF) models outperformed regularized regression, partial least squares, k-nearest neighbors, support vector machines, and a deep neural network. The best RF model, using PAC traits, LW, and ET (Pred_DMI3), achieved R2 = 0.77, root mean square error of 279\u2009g\/d, and mean absolute percentage error\u2009=\u200913.8% in the combined test set. Models using only PAC traits performed comparably to models including BW and ET with only marginal losses in validation metrics. Mixed-model analyses indicated strong individual-level correlations between predicted and observed DMI (r\u1d62 = 0.79\u20130.81) after adjusting for breed, diet, and trial. These results demonstrate that short-term PAC-derived gas traits can provide scalable proxies for daily DMI in gestating ewes under controlled indoor conditions, with potential application in intake phenotyping and benchmarking.<\/jats:p>","DOI":"10.1093\/jas\/skag158","type":"journal-article","created":{"date-parts":[[2026,5,11]],"date-time":"2026-05-11T11:23:10Z","timestamp":1778498590000},"source":"Crossref","is-referenced-by-count":0,"title":["Predicting dry matter intake in gestating ewes using greenhouse gas measurements from portable accumulation chambers"],"prefix":"10.1093","volume":"104","author":[{"given":"Gareth F","family":"Difford","sequence":"first","affiliation":[{"name":"Norwegian University of Life Sciences Institute of Animal and Aquacultural Sciences, , \u00c5s, N-1432,","place":["Norway"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Jette","family":"Jakobsen","sequence":"additional","affiliation":[{"name":"The Norwegian Association of Sheep and Goat Breeders , \u00c5s, N-1430,","place":["Norway"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Ingjerd","family":"D\u00f8nnem","sequence":"additional","affiliation":[{"name":"Norwegian University of Life Sciences Institute of Animal and Aquacultural Sciences, , \u00c5s, N-1432,","place":["Norway"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Geir","family":"Steinheim","sequence":"additional","affiliation":[{"name":"Norwegian University of Life Sciences Institute of Animal and Aquacultural Sciences, , \u00c5s, N-1432,","place":["Norway"]}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Bente A","family":"\u00c5by","sequence":"additional","affiliation":[{"name":"Norwegian University of Life Sciences Institute of Animal and Aquacultural Sciences, , \u00c5s, N-1432,","place":["Norway"]}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"286","published-online":{"date-parts":[[2026,5,16]]},"reference":[{"key":"2026061914085021400_skag158-B1","doi-asserted-by":"publisher","first-page":"107081","DOI":"10.1016\/j.smallrumres.2023.107081","article-title":"Effects of sheep breed and grass silage quality on voluntary feed intake and enteric methane emissions in adult dry ewes","volume":"227","author":"\u00c5by","year":"2023","journal-title":"Small Rumin Res"},{"key":"2026061914085021400_skag158-B2","doi-asserted-by":"publisher","first-page":"178","DOI":"10.1111\/j.1365-2435.2006.01209.x","article-title":"Estimating phenotypic correlations: correcting for bias due to intraindividual variability","volume-title":"Funct. 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