Journal of Dairy Science最新文献

{"title":"A meta-analysis of effects of seaweed and other bromoform-containing feed ingredients on methane production, yield, and intensity in cattle.","authors":"Ermias Kebreab, Eleanor May Pressman, John-Fredy Ramirez-Agudelo, André Bannink, Sanne van Gastelen, Jan Dijkstra","doi":"10.3168/jds.2025-26960","DOIUrl":"https://doi.org/10.3168/jds.2025-26960","url":null,"abstract":"<p><p>Methane (CH₄) emissions from ruminants contribute significantly to global GHG emissions. Bromoform (CHBr₃)-containing feed ingredients, such as Asparagopsis seaweed, have emerged as promising tools to reduce enteric CH₄ emissions. This meta-analysis quantitatively assessed the effects of CHBr₃-containing seaweeds and synthetic CHBr₃-based additives on CH₄ production (g/d), CH₄ yield (g/kg DMI), and DMI, as well as CH₄ intensity (g/kg product) and production (milk or daily gain in dairy and beef cattle, respectively). Data were collected from 14 studies, with 39 treatment mean differences for CH₄ production, comprising both beef and dairy cattle fed CHBr₃-containing ingredients, while accounting for dose, DMI, and diet composition. The random-effects model's estimates revealed that at an average CHBr₃ dose of ≈28.3 mg/kg DM, CH₄ production was reduced by 47.3%, CH₄ yield by 43.3%, and CH₄ intensity by 39.0%, with increases in the CHBr₃ dose resulting in larger efficacy in mitigating CH₄ emissions. The efficacy of CHBr₃ was influenced by cattle type, with greater mitigation effects in beef cattle than dairy catle, and by dietary composition, with greater reductions observed in diets higher in starch, whereas higher NDF levels attenuated the effect of CHBr₃. At the average CHBr₃ dose, estimated DMI was significantly reduced by 6.45% and 3.26% in dairy and beef cattle, respectively, with increases in CHBr₃ dose resulting in larger DMI reductions. The significant reduction in DMI did translate into a significant effect on milk yield (-4.60%) at average CHBr₃ dose. Carrier type (oil vs. biomass), measurement technique, and cattle type influenced the results. The use of an oil carrier was associated with more pronounced reductions, particularly in CH₄ intensity. Additionally, respiration chambers yielded significantly greater CH₄ reductions compared with other measurement methods. This study highlights the CH₄-mitigating potential of feed ingredients containing CHBr₃, providing predictive models to optimize CH₄ reduction strategies under diverse production conditions. Future research should address long-term effects, dietary optimization, and practical implementation.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768140","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Modeling shade use of grazing dairy cows using sensor-derived data and machine learning.","authors":"Simon J R Woodward, Lydia J Farrell, Chris R Burke, J Paul Edwards","doi":"10.3168/jds.2025-26904","DOIUrl":"https://doi.org/10.3168/jds.2025-26904","url":null,"abstract":"<p><p>The health, welfare, and production impacts of heat stress are of increasing concern to dairy farmers. For cows grazing pasture, solar radiation is a key driver of heat stress load, and provision of shade (e.g., trees) is a primary mitigation option. To date, research on shade use choices by dairy cows has been limited to small-scale observation-based studies, and analysis at a commercial scale using sensor-derived data using machine learning has not been attempted. This study quantified the availability and use of shade at a herd level using cow global positioning system location data from herds of lactating dairy cows grazing pasture for 1 month in summer on 4 farms in the North Island of New Zealand, along with 15-min weather data and software that predicts potential shaded areas from aerial light detection and ranging imagery. Farms ranged from 60 to 400 ha of flat to rolling terrain. Cow shade use was quantified as the percentage of cows in shade above what would be expected from independent random walking and was modeled using 9 contrasting machine learning approaches. Shade use was found to be predictable and dependent on several interacting variables. Shade use increased when solar radiation exceeded 2 MJ/m² per hour, provided at least 1.3 m² of shade was available per cow, especially when air temperature exceeded 24°C and wind speed was less than 4.2 m/s. These results can be applied to historic or forecast weather data to help farmers make informed decisions about investment in shade resources or to maximize the use of existing resources.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768193","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early-life 2'-Fucosyllactose and its combination with Bifidobacterium bifidum TMC3115: Sex-specific effects in learning, spatial memory, and hyperactivity in juvenile spontaneous hypertensive rats as an attention deficit/hyperactivity disorder model.","authors":"Yang Yang, Simou Wu, Jianxiu Liu, Yating Luo, Jinxing Li, Kai Wang, Fang He, Ruyue Cheng","doi":"10.3168/jds.2025-26717","DOIUrl":"https://doi.org/10.3168/jds.2025-26717","url":null,"abstract":"<p><p>This study investigated the preventive effects of early-life intervention with 2'-fucosyllactose (2'-FL) or synbiotic (2'-FL plus Bifidobacterium bifidum TMC3115) on newborn spontaneous hypertensive rats (SHR) as an attention deficit/hyperactivity disorder (ADHD) model, focusing on the microbiota-gut-brain (MGB) axis. In male SHR, 2'-FL intervention increased time spent and distance moved in Morris water maze, and upregulated mRNA expression related to γ-aminobutyric acidergic, serotonergic, and noradrenergic systems in hippocampus. Increased Romboutsia, Clostridium_sensu_stricto_1, and decreased Muribaculaceae after 2'-FL intervention were associated with improved learning and spatial memory. In female SHR, synbiotic intervention reduced hyperactivity in the open field test and increased expression of tyrosine hydroxylase and dopamine transporter in striatum. Synbiotic also promoted gut microbiota diversity and suppressed the growth of Bacillus and Turicibacter. Overall, early-life 2'-FL and synbiotic interventions offered sex-specific benefits for SHR by regulating gut microbiota and mediating MGB pathways, providing new insights for prebiotics and psychobiotics in early ADHD prevention.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768144","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pair housing benefits performance and activity of dairy calves with influences of season.","authors":"J Bonney-King, E E Lindner, C M M Bittar, E K Miller-Cushon","doi":"10.3168/jds.2024-25819","DOIUrl":"https://doi.org/10.3168/jds.2024-25819","url":null,"abstract":"<p><p>The objective of this study was to evaluate effects of social housing on calf performance and activity within different seasons. Within 24 h of birth, Holstein heifer calves were assigned to either individual (IH; n = 50 pens) or pair housing (PH; n = 50 pens), balanced across seasons in a humid subtropical climate (cool season, mid-October to mid-April, 17 ± 5°C, mean ± SD, and warm season, mid-April to mid-October, 26 ± 3°C, temperature-humidity index consistently >65). Calves received 8 L/d of milk replacer, until gradual weaning over 10 d beginning at 43 ± 3 d of age, and calf starter and water ad libitum. The presence of fever (≥39.4°C) and scours (fecal consistency assessed visually at the pen level) were assessed 5 d/wk. Calves were weighed at birth, before and after weaning, and 1 wk postweaning. Pen-level starter intake was recorded 4 d/wk. Standing time was determined using leg-based accelerometers. Calves born in the cool season scoured later and for fewer days, with no effect of social housing. Fever presentation was similarly reduced in the cool season, in interaction with housing treatment; fewer PH than IH calves had a fever in the cool season. Calves in PH pens consumed more starter by wk 5 of life, had greater ADG pre- and postweaning, and had greater BW by the end of weaning. Some performance advantages attributed to PH compared with IH calves were most apparent in the cool season, including starter intake during weaning (+0.17 kg/d; SE = 0.021) and postweaning ADG (+0.35 kg/d; SE = 0.1). Calves in PH pens maintained greater BW 1 wk postweaning, with no effect of season. Standing time was greater in PH pens, particularly in the evening, with daily peaks in activity falling later in the day during the warm season. These results support clear benefits of PH dairy calves from birth, alongside evidence that performance advantages attributed to social housing may be enhanced in cool weather or dampened by heat stress.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768194","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Enteric methane production and neutral detergent fiber plasticity: A potential indicator trait for forage utilization in dairy breeding.","authors":"T A Skjerve, K S Eikanger, A Kidane, E Prestl Kken, H Fjerdingby Olsen, B Aspeholen Åby, H Volden, G Klemetsdal","doi":"10.3168/jds.2025-26701","DOIUrl":"https://doi.org/10.3168/jds.2025-26701","url":null,"abstract":"<p><p>This study aims to evaluate the use of a reaction-norm model, with NDF concentration in the ration as an environmental gradient, and its plasticity as a candidate phenotype for identifying animals that efficiently utilize plant fiber. A dataset from a feeding trial with 40 cows fed different types of silage and concentrate with differing NDF concentrations was used. Single-visit ln-transformed methane production was analyzed using a model accounting for systematic environmental effects; among these a fixed effect of NDF concentration as a fixed effect, along with random effects for individual intercept and slope, both of which were significant. Plasticity, defined as the individual slope of the response in ln-transformed methane production to NDF concentration in the ration, was further examined in relation to underlying data structure and NDF digestibility. Underlying data structure was analyzed with an explanatory factor analysis of mean and variance for variables not included in the reaction-norm model, interpreted as either feed composition or feed intake and activity. The individual slope showed a significant positive relationship to individual NDF digestibility, suggesting that it could serve as an indicator trait to breed cows that efficiently utilize roughage. However, this finding needs to be validated in a larger dataset suitable for genetic analysis.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768220","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fermented casein with Lactobacillus gasseri KML39 alleviates systemic inflammation interacting with the gut-brain-microbiome axis in dextran sulfate sodium-induced colitis mice.","authors":"Hyo Su Choi, Jae Yeon Joung, Hyun Jin Bae, Nam Su Oh","doi":"10.3168/jds.2025-26659","DOIUrl":"https://doi.org/10.3168/jds.2025-26659","url":null,"abstract":"<p><p>This study investigated the preventive effects of fermented casein with Lactobacillus gasseri KML39 (FSC) on systemic inflammation through modulation of the gut-brain-microbiome axis in a dextran sulfate sodium (DSS)-induced colitis mouse model. Lactobacillus gasseri KML39 was selected based on its superior casein fermentation properties, proteolytic and antioxidant activities, and probiotic potential, including acid and bile tolerance and intestinal adhesion ability. We found that FSC significantly suppressed the expression of proinflammatory cytokines (COX-2, iNOS, TNF-α, IL-1β, and IL-6) and reduced nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells. In DSS-induced colitis mice, body weight loss, shortened colon length, and colonic tissue damage were observed compared with the control group. Dextran sulfate sodium also activated NF-κB signaling, leading to the upregulation of iNOS and COX-2 in both colonic and brain tissues, along with elevated serum TNF-α and corticosterone levels. Furthermore, DSS treatment compromised intestinal and blood-brain barrier integrity, as indicated by the downregulation of tight junction proteins (occludin and claudin-5). Additionally, DSS negatively regulated neurotransmitter receptors (NMDAR, GABAR, and D2DR) and neurodevelopmental markers (BAX and Bcl-2) in the brain, suggesting neuroinflammatory and neurodegenerative effects. The FSC pretreatment effectively restored tight junction integrity, attenuated neuroinflammation, and improved gut microbiota composition. Notably, Proteobacteria and Bacteroides were significantly enriched in the DSS-treated group, whereas their abundance was normalized by FSC pretreatment. These findings highlight systemic inflammation as a key driver of colitis-associated neuroinflammation and demonstrate the potential of FSC as a therapeutic agent for gut-brain-microbiome axis dysfunction in colitis.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768221","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"TGF-β3-mediated phagocytosis protects mammary epithelial cells of ketotic dairy cows against metabolic stress-induced inflammatory damage.","authors":"Renxu Chang, Hongdou Jia, Yuanyuan Chen, Juan J Loor, Qiushi Xu, Li Ma, Ming Li, Taiyu Shen, Xiaobing Li, Chuang Xu, Xudong Sun","doi":"10.3168/jds.2025-26828","DOIUrl":"https://doi.org/10.3168/jds.2025-26828","url":null,"abstract":"<p><p>The supraphysiological levels of free fatty acids (FFA) during early lactation led to an inflammatory response in the mammary gland of ketotic cows, which may be attributed to the untimely clearance of apoptotic cells (AC). Given the engulfment role of mammary epithelial cells for AC and the regulation of TGF-β3 on phagocytosis, we speculated that TGF-β3-mediated phagocytic function is closely related to inflammatory response in the mammary gland of ketotic cows. The objective of this study was to elucidate (1) the inflammatory state and phagocytic function of mammary epithelial cells and activity of the TGF-β3 pathway in mammary gland of ketotic cows, and (2) the role of TGF-β3-mediated phagocytosis on the inflammatory response of bovine mammary epithelial cells in response to exogenous FFA. In this study, excessive proliferation of AC, NF-κB/MAPK-mediated inflammatory response, TLR4-mediated local natural immune dysfunction, phagocytic dysfunction of mammary epithelial cells, and activation of the TGF-β3 pathway were detected in the mammary gland of ketotic cows or in immortalized bovine mammary epithelial (MAC-T) cells in response to exogenous FFA. Knockdown of TLR4 attenuated the FFA-induced inflammatory response in MAC-T cells. Overexpression of TGF-β3 exacerbated FFA-induced TLR4-mediated local immune dysfunction and inflammatory response by aggravating phagocytic responses. Knockdown of TGF-β3 attenuated the overactivation of inflammation resulting from FFA challenge through inhibition of the TLR4 pathway, which improved phagocytic ability in MAC-T cells. Taken together, TGF-β3-mediated phagocytosis may be a promising therapeutic target for reducing the negative effect of FFA-induced inflammation in mammary gland of dairy cows with ketosis.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768197","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Associations between periparturient calcium dynamics of multiparous Holstein cows and inflammation markers during the transition period.","authors":"G M Graef, A Sipka, S Tompkins, C R Seely, J A A McArt, T R Overton","doi":"10.3168/jds.2024-25979","DOIUrl":"https://doi.org/10.3168/jds.2024-25979","url":null,"abstract":"<p><p>Recent work has established that proper classification of cows based on their periparturient status has important implications for risks of health, production, and reproduction outcomes during the postpartum period. However, the dynamics of blood calcium (Ca) status and inflammation are far less understood. The objective of this study was to determine the relationship between subclinical hypocalcemia (SCH) dynamics and periparturient circulating serum amyloid-A (SAA), haptoglobin (Hp), tumor necrosis factor-α (TNFα), interferon-γ (IFNγ), and interleukin-10 (IL-10) concentrations, DMI, and milk production during the first 9 wk of lactation. Data collected from multiparous Holstein cows (n = 96) were retrospectively classified into 1 of 4 calcemia groups based on blood concentrations of total Ca (tCa) at 1 and 5 DIM: normocalcemic (NC; [tCa] >1.95 mmol/L at 1 DIM and >2.32 mmol/L at 5 DIM, n = 53); transient SCH (tSCH; [tCa] ≤1. 95 mmol/L at 1 DIM and >2.32 mmol/L at 5 DIM, n = 15); delayed SCH (dSCH; [tCa] >1. 95 mmol/L at 1 DIM and ≤2.32 mmol/L at 5 DIM, n = 15); and persistent SCH (pSCH; [tCa] ≤1. 95 mmol at 1 DIM and ≤2.32 mmol/L at 5 DIM, n = 13). The MIXED procedure of SAS (v. 9.4, SAS Institute Inc.) was used to analyze pre- (-28 and -1 d relative to calving) and postpartum (1, 3, 5, and 7 DIM) blood mineral concentrations, SAA, Hp, cytokines, milk production, and differences between Ca groups, using repeated measures for time. Prepartum blood concentrations of IL-10 tended to be greater in tSCH cows compared with NC, dSCH, and pSCH. Postpartum concentrations of Hp, SAA, and TNFα were different by Ca group. Concentrations of SAA and Hp were highest in the pSCH group at d 3, and TNFα was highest for cows categorized as dSCH, irrespective of time. Overall, our results suggest that cows experiencing different SCH dynamics display different patterns of inflammatory markers and that elevated concentrations of proinflammatory biomarkers accompany some categories of hypocalcemia during the early lactation period.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Postbiotics derived from wine grape seed extract and whey with lactic acid bacteria alleviate muscle atrophy by modulating genes involved in inflammation, myogenesis, and bone metabolism.","authors":"Yejin Jeong, Kunho Seo, Subin Hwang, Yongsoon Park, Hyunsook Kim","doi":"10.3168/jds.2024-26229","DOIUrl":"https://doi.org/10.3168/jds.2024-26229","url":null,"abstract":"<p><p>A postbiotic product (WDG), derived from the bioconversion of wine grape seed flour extract (GSE) and branched-chain amino acid-rich whey using Lentilactobacillus kefiri DH5 (DH5), may synergistically improve bioavailability and bioactivity to alleviate muscle atrophy. The left hindlimbs of C57BL/6J mice were immobilized for 2 wk, and the mice were randomly divided into 5 groups fed a high-fat (HF) diet (CON), 5% grape seed flour (G), whey (W), W + DH5 (WD), or 2.5% G + W + DH5 + GSE (WDG). The WDG group showed the most significant improvements in holding impulse time, muscle mass, and expression of genes related to muscle growth markers (MyoD, IGF-1, atrogin-1), with its antisarcopenic effects being superior to those of G or WD alone. The RNA-sequencing analysis revealed that WDG positively regulated genes related to anti-inflammation, phagocytosis, angiogenesis, myogenesis, bone metabolism, and brown adipose tissue development. These findings suggest that WDG may be a potent natural functional product for the management of sarcopenia.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768195","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Potential of novel feed efficiency traits for dairy cows based on respiration gas exchanges measured by respiration chambers or GreenFeed.","authors":"Pekka Huhtanen, Ali-Reza Bayat","doi":"10.3168/jds.2025-26683","DOIUrl":"https://doi.org/10.3168/jds.2025-26683","url":null,"abstract":"<p><p>Residual feed intake (RFI), calculated as a difference between observed and predicted intake, is a commonly used estimate of feed efficiency (FE). Determination of FE in practical dairy herds is challenging, as it requires accurate estimation of feed intake of individual cows. Alternatively, FE could be estimated as a difference between observed and predicted metabolic losses derived from gas exchanges. The objectives were to compare respiration chambers (RC) and the GreenFeed (GF) system in estimating FE based on the gas data, and to compare FE estimated from measured feed intake or gas data. The study was conducted using 32 Nordic Red dairy cows (DIM 159 ± 63, BW 634 ± 60 kg, and milk yield 28.9 ± 6.7 kg/d) fed a grass silage-based diet (CP 152 g/kg DM, NDF 395 g/kg DM). The study included two 14-d periods with the GF system with a 1-wk period in RC chambers (3-d measurements) between the GF periods. Residual CO₂ production (RCO₂), residual O₂ consumption (RO₂) and residual heat production (RHP) were estimated as observed minus predicted values derived from energy requirements. Root means squared errors of DMI prediction were smaller for models based on CO₂ or O₂ and ECM yield compared with ECM + BW model both with RC and GF data with minor differences between the methods. The relationship between GF and RC was slightly better for RO₂ (R² = 0.68) and RHP (R² = 0.67) compared with RCO₂ (R² = 0.59). Seventy-five percent of the top 50% (12/16) cows in GF were ranked among the top 50% in RC. Repeatability values of different FE traits were similar or higher for the data based on gas data measured by GF compared with the corresponding values based on measured feed intake. Residual CO₂ production explained 57% of variation in residual ME intake (RMEI). Gross FE expressed as ECM/CO₂ explained 82% of gross FE expressed as ECM/DMI. When the cows were divided into low, medium, and high RCO₂ groups, the differences in various FE traits were consistent with those based on measured feed intake. The difference in RMEI between the Low- and High-RCO₂ cows was 15 MJ/d. Low-RCO₂ cows produced 13% less methane per kilogram ECM, had higher diet digestibility, and produced less heat than high-RCO₂ cows. It is concluded that estimating FE from gas data measured by the GF system has a potential to rank the cows according to FE in farm conditions without requiring measuring feed intake.</p>","PeriodicalId":354,"journal":{"name":"Journal of Dairy Science","volume":" ","pages":""},"PeriodicalIF":4.4,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}