Enteric CH4 Emissions Research Articles

Providing an alternate electron sink to methane (CH4) is a crucial step in reducing enteric CH4 emissions. Comparing the effects of CH4-utilizing methanotroph bacteria (Methylococcus capsulatus; MC) and its combination with pure strains of rumen bacteria or mixed rumen fluid can offer biological insights into methanogenesis pathways and CH4 consumption. The primary objectives of this study were to investigate the impact of inoculating with M. capsulatus on the growth rates of rumen bacteria, including methanogens and mixed rumen fluid, as well as fermentation rates, ruminal gas production, CH4 emissions, and other environmental-impacting gases (N2O, H2S). Three experiments were carried out using in vitro ANKUM gas production systems (Exp. 1 and 2) and continuous recirculating flux chamber systems (Exp. 3). In Exp. 1, four strains of rumen bacteria-Streptococcus bovis [SB], Ruminococcus flavefaciens [RF], Methanobrevibacter smithii [MS], and M. capsulatus [MC]-were used to determine the effect of CH4-utilizing bacteria (e.g., MC) on specific growth rate, volatile fatty acid (VFA) production, and ruminal CH4 emissions in a combination with these bacterial strains. Results from Experiment 1 showed that MS produced the most CH4 among the strains. When cocultured with MC, no CH4 was detected, indicating that MC could utilize most of the CH4 produced in coculture with MS and other bacterial strains. There was little difference in total and cumulative gas production with varying MC doses (Exp. 2). However, in the presence of MC, CH4 production (percentage or g DM) decreased significantly (P < 0.01) as MC addition increased. Conversely, substrates containing both grain- and forage- based diets with MC increased N2O emissions per gram of DM (µg/g DM) or total N2O production (ppm), with treatment and basal diet interactions (P < 0. 01). In Exp. 3, using a continuous recirculating flux chamber system, CH4 flux significantly reduced (P < 0.001) over time in both basal diets with MC inoculum. However, fermentation rates varied between treatments and diets. These findings demonstrate that adding MC inoculum to in vitro rumen fermentation chambers significantly reduces CH4 emissions compared to controls.

The enteric methane (CH4) emission from dairy cattle is a significant factor contributing to anthropogenic climate change and the energy loss of animals. The objective of this study was to evaluate the prediction accuracy of the existing CH4 estimation models from dairy cattle, and to identify the most reliable model for quantifying CH4 emission. A database was compiled from 135 treatment means obtained from 81 peer-reviewed literatures, which included data on dietary composition, energy intake, and enteric CH4 emission from dairy cattle. Forty existing dairy cattle prediction models were evaluated using this dataset based on the root mean square prediction error (RMSPE), concordance correlation coefficient (CCC), the ratio of RMSPE to standard deviation (RSR), and error decomposition indicators (ECT, ER, and ED). Results indicated that the RSR of model 38 was the lowest (0.71) but there were large prediction errors. Considering all evaluation indicators, model 21, which included dry matter intake (DMI), demonstrated the most robust predictive performance (RSR = 0.83, RMSPE = 14.41%, ECT = 3.42%, ER = 0.74%, ED = 96.75%, CCC = 0.58). Therefore, it is recommended for estimating enteric CH4 emissions from dairy cattle. Future research will need to further improve the accuracy and robustness of enteric CH4 prediction models by establishing a more comprehensive large-scale database, and expand the applicability of the model in various dairy farming systems.

Effects of 3-nitrooxypropanol on enteric methane emissions and milk production characteristics in dairy cows fed a high corn-silage diet in different environmental conditions.

Graduate Student Literature Review: Limitations in feeding red seaweed Asparagopsis species for enteric methane mitigation in ruminants.

IntroductionEnteric methane (CH4) emissions from ruminant livestock production systems pose a significant challenge to efforts to mitigate global climate change. The novel feed additive 3-nitrooxypropanol (3-NOP) has the capacity to inhibit rumen methanogenesis and significantly reduce the volume of enteric CH4 emissions produced by livestock systems. However, heterogeneity in CH4 mitigation from 3-NOP supplementation prevents livestock producers from determining the actual impact of supplementation on CH4 emissions. This meta-analysis aimed to understand the variables responsible for the heterogeneity in CH4 mitigation from 3-NOP supplementation in confinement-fed beef and dairy cattle.MethodsUsing 30 in vivo studies (83 treatments) that continuously supplemented 3-NOP at a range of doses from 40mg to 338mg dose (mg 3-NOP/kg dry matter intake; DMI), a mixed-effects multistep regression examined the impact of 3-NOP supplementation on CH4 yield.ResultsOn average, 3-NOP supplementation reduced CH4 yield by 25.9% in beef cattle and 26.4% in dairy cattle, at the recommended dose of 60mg 3-NOP/kg DMI. Results showed that the anti-methanogenic potential of 3-NOP was influenced by 3-NOP dose (mg 3-NOP/kg DMI) and DMI kg/head-1/day-1.DiscussionAlthough studies showed a strong positive relationship between 3-NOP dose and CH4 emissions (P &amp;lt;0.0001), DMI was observed to have a greater influence of CH4 abatement than 3-NOP dose. This suggests that the volume and timing of CH4 production influences the availability of 3-NOP in the rumen during methanogenesis more than 3-NOP dose itself. This paper uses this understanding to develop equations that can estimate future CH4 abatement in real farm systems, allowing producers the capacity to quantify the impact of 3-NOP on their greenhouse gas emissions and receive recognition for avoided CH4 emissions. However, these equations are highly influenced by DMI and are only suitable for confinement-fed systems that consume an equal or greater volume of ration and are not a substitute for measuring CH4 emissions, which would provide producers with the actual volume of CH4 emissions avoided.

Abstract The efficacy of 3-NOP in reducing enteric methane (CH4) emissions in dairy and beef cattle diets is well-documented. However, to our knowledge, there are no studies evaluating inclusions of 3-NOP in dosages lower than 100 ppm under tropical conditions in Nellore animals. Therefore, this study aimed to evaluate two levels of 3-nitrooxypropanol (3-NOP) as a feed additive on performance, CH4 emission, and rumen microbiome of Nellore cattle in a feedlot. Seventy-five 20-month-old Nellore bulls [361.6 ± 30.08; body weight (BW) ± SD] were individually housed with ad libitum access to feed and water. Animals were distributed in a completely randomized design, with 3 treatments, 25 animals per treatment. The treatments were: 1) CON, control (basal diet + mineral premix with monensin 25 mg/kg DM without additive 3-NOP), 2) 3-NOP65 (Basal diet + mineral premix with monensin 25 mg /kg DM + 65mg/kg of DM of 3-NOP; Bovaer®), 3) 3-NOP85 (Basal diet + mineral premix with monensin 25 mg /kg DM + 85 mg/kg of DM of 3-NOP; Bovaer®). The adaptation dietary program consisted of ad libitum feeding of 3 adaptation diets for 3 weeks (21 days), with the concentrate level of the diet increasing from 50 to 60% in week 1, 60 to 75% in week 2, and 75 to 88% in week 3, DM basis. The experiment lasted 115 d. Enteric CH4 emissions were estimated using the sulfur hexafluoride (SF6) tracer gas technique (16 animals per treatment), during the 104 to 110 days of the experimental period. Rumen microbiome samples, from the same 16 animals used for CH4 data, were collected on d 115 at the slaughterhouse, samples were processed and analyzed with the ZymoBIOMICS® Targeted Sequencing Service. The animal performance was not affected by the increasing doses of dietary 3-NOP. Dry matter intake increased linearly in response to 3-NOP addition. The 3-NOP inclusion tended to quadratically increase the digestibility of DM (P = 0.07), and quadratically increase the digestibility of CP (P = 0.04). The addition of 65 and 85 mg/kg of 3-NOP (DM basis) was effective on reducing CH4 emissions by 13.2 and 26.7%, respectively, when compared to CON diet with no detrimental effects on animals’ health. Likewise, linear reduction was detected for CH4 the emission intensity of CH4 per HCW by 14.3% and 27.6% at doses 65 and 85 mg/kg of DM. There was a reduction of the relative abundance of the phyla Euryarchaeota with increasing doses of 3-NOP, a phylum that encompasses methanogen microorganisms. Overall, increasing doses of 3-NOP were effective in reducing CH4 emissions of Nellore cattle in a feedlot system in a dose-dependent manner, with no detrimental effects on animals’ performance and health.

Abstract The reduction in enteric methane (CH4) emissions from cattle continues to be one of the top priorities in order to contribute to the sustainability of beef production in the U.S. The cow-calf segment of the beef industry is responsible for 61% of the total greenhouse gas emissions directly related to beef production. While many strategies have been studied to mitigate enteric CH4 emissions, very few of them focus on the cow-calf segment. Therefore, this study evaluated the effect of internal and external parasite control strategies on animal performance and CH4 emissions in lactating Angus crossbred beef cows. The study was conducted from May to October of 2023 and 2024. Forty-eight multiparous cow-calf pairs were utilized in each year. The experiment followed a randomized complete block design with four treatments in a 2 × 2 factorial arrangement. Factors included using or not internal (INT) or external (EXT) parasite control methods. Each year on d 0, animals were sorted by age and weight, randomly grouped into four cow-calf pairs assigned to 12 different pastures (n = 4 cow-calf pairs/pen, 3 pens/treatment each year), received the first dose of parasite control and a permeation tube containing ±3.4 g of sulfur hexafluoride (SF6) gas with an average release rate of 5.78 mg/d was dosed via oral. Internal parasite control involved administering a drench containing 11.36% albendazole (45 mL/cow). For EXT parasite control, animals were equipped with ear tags coated with 50% organophosphate insecticides (2 ear tags per cow and 1 per calf) and treated with a pour-on application of 1% permethrin synergized with 1% piperonyl butoxide. On d 1, the pour-on was re-applied on every sampling day thereafter. On d 1, 35, 70 (weaning day), and 105, body weight (BW) and body condition score (BCS) were recorded, and photographs of the cows’ right-lateral side were taken to determine horn fly load. Enteric CH4 emissions were collected using the SF6 tracer technique. With Year 1 only analyzed thus far, there was no significant effect of INT, EXT, or INT×EXT interaction (P &amp;gt; 0.05) on CH4 emissions. Similarly, BW, BCS, and fly counts had no effect on daily CH4 emission rates (P &amp;gt; 0.05). However, when CH4 was expressed as per calf’s weight gain, fly counts had a significant effect (P &amp;lt; 0.05), with CH4 emissions increasing by 0.034 g/d per each additional fly per cow. This study demonstrated that horn fly load may affect CH4 emissions intensity in cow-calf production systems when expressed per kg of calf produced.

Abstract Cattle are the largest emitters of greenhouse gases (GHG), specifically methane (CH4), due to their ruminant digestive system. Cows are unable to directly digest the complex carbohydrates in the plant tissues they consume. Instead, they rely on enteric fermentation from microorganisms in the rumen to break down these tissues. During this process, hydrogen and carbon dioxide in the rumen are converted into CH4, which is expelled through eructation. Methane production is energetically inefficient to the animal, with cattle typically losing 6% of their ingested energy as enteric CH4. Research on enteric CH4 emissions of grazing cattle is limited, therefore deserving more exploration. The goal of our study was to characterize the seasonal variation in enteric CH4 emissions of beef cows grazing native sagebrush steppe. The study began in spring of 2024 with twenty-two cows (Angus × Hereford, 545 ± 17 kg) from the Eastern Oregon Agricultural Research Center (EOARC; Burns, Oregon). Methane emissions (g/day) were measured using the Greenfeed Pasture System monitoring units (C-Lock). Prior to the grazing season, all cows were acclimated the monitoring units. During the acclimation period, they were maintained as a group and provided meadow hay ad libitum. Fifteen cows were successfully acclimated. After the acclimation period, cows and monitoring units were relocated to the Northern Great Basin Experimental Range (NGBER; Riley, Oregon) for the measurement of enteric CH4 emissions during the grazing season over summer and fall. The monitoring units were placed near water sources and programmed to record up to 8 visits per cow each day, with alfalfa pellets used as an enticement. Cows were fitted with virtual fence collars (Vence) to assist with grazing management and composite forage samples were collected for forage nutrient analyses. Preliminary data for CH4 emissions during spring, summer and fall were analyzed as repeated measures with the MIXED procedure of SAS (SAS Inst. Inc., Cary, NC, USA). Statistical significance was defined at P ≤ 0.05. Spring, summer, and fall forage CP and TDN were 8.5% and 56%, 3.5% and 57%, and 2.8 % and 55%, respectively. Approximately 9,000 CH4 emission readings were collected from spring through fall. Methane emissions were greatest (P &amp;lt; 0.0001) during summer (213 ± 1.06 g/cow daily), and similar between spring and fall (198 ± 1.40 g/cow daily; P = 0.51), illustrating the seasonal variation in emissions of grazing beef cattle.

Abstract The ruminant livestock sector contributes to global greenhouse gas emissions. Thus, there is a need to develop novel mitigation strategies, especially for pasture-based systems as less than half of the identified strategies are applicable to grazing systems. This study aimed to examine the use of pelleted bromoform-containing seaweed (Asparagopsis taxiformis) marketed as Brominata, as an enteric methane (CH4) inhibitor in grazing beef cattle under real-world farm conditions. The study was conducted at the Selkirk division of Matador Ranch and Cattle in Dillon, Montana, USA, situated in a semi-arid climate with cold, dry winters and hot, wet summers. Twenty-four crossbred Wagyu-Angus beef steers, with an average liveweight of 399 ± 21.7 kg, were allocated to two treatment groups: Control and Brominata. Measurements of CH4, carbon dioxide (CO2), and hydrogen (H2) emissions were conducted using the GreenFeed system which also was used to administer the pelleted supplements. The control group received a pellet composed of 65% wheat mids, 15% molasses, and 20% bentonite (CHS Nutrition, Great Falls, Montana, USA). The Brominata group received a pellet containing Brominata (20%, Blue Ocean Barns, Kailua Kona, HI, USA), distillery solubles (15%), wheat mids (65%), a palatability enhancer (Inhace, 0.25%, Qualitech, Chaska, Minnesota, USA), molasses coating, and wheat mids dusting. The bromoform concentration in the pellets was 1.4 mg g/dry matter. The study was conducted in an intensive irrigated pasture, where the steers remained together throughout the experiment. Central pivot irrigation and rotational grazing management were used with a fixed stocking rate. Statistical analysis was conducted using SAS 9.4, with a model incorporating fixed effects for treatment, time, their interaction, and a covariate, while accounting for animal variations as a random effect within each phase. Three phases of bromoform intake were identified: a 3-week ramp-up phase, a 3-week optimal phase, and a 2-week decreasing phase. No differences were observed between the groups in terms of weekly initial and final liveweight, average daily gain, or predicted dry matter intake. However, during the optimal and decreasing phases, average enteric CH4 emissions were significantly (P &amp;lt; 0.05) reduced in steers that received Brominata supplementation compared to the Control (115 vs. 185 g/d, respectively). CO2 emissions were similar between the two groups (6.8 vs. 7.2 kg/d), while H2 emissions were lower (P &amp;lt; 0.05) in the control group (3.4 vs. 1.8 g/d). The findings suggest that pelleted bromoform-containing feed additive has the potential to reduce enteric CH4 emissions from grazing beef cattle. The observed 37.7% average reduction in CH₄ production, achieved without compromising animal performance, suggests a promising approach for mitigating the environmental impact of livestock farming.

Abstract A grazing trial was conducted to evaluate the growth performance and enteric gas emissions of beef heifers effects of fed a plant-derived essential oil supplement (Agolin®). For this study, 63 crossbred beef heifers were used (BW = 274 ± 42 kg) and grazed a 24-hectare triticale (Triticosecale spp.) pasture near Minneola, Kansas. Heifers were stratified based on BW and pre-trial AHCS (Automated Head Chamber System) acclimation rates into one of two supplementation treatments: 1) AGO: Agolin® with dry distillers grain at 0.5 kg/d, or 2) CON: dry distillers grain at 0.5 kg/d. The primary objectives were to assess differences in enteric methane (CH₄) and carbon dioxide (CO₂) emissions, and average daily gain (ADG) with and without Agolin® supplementation. Body weights were recorded at the start (day 0), midpoint (day 35), and conclusion of the 78-day grazing period. Enteric emissions were measured using a GreenFeed emission measurement system (AHCS; C-Lock Inc., Rapid City, SD). Supplement treatments were offered using SmartFeed Pro units (C-Lock Inc., Rapid City, SD) to allow individual-heifer access and consumption while enabling comingling of treatments in one experimental pasture. Only animals with ≥20 SmartFeed Pro visits (and an average supplement intake ≥0.25 kg/day) over the trial were selected to represent consistent supplement users (n = 28). Statistical analyses were conducted in R (version 4.4.1). General linear models were used to assess differences between treatments for ADG (kg/d), CH4 (g/d), CO2 (g/d) and emission intensity (g CH4 per kg ADG) with potential influential points identified using Cook’s distance model. ADG did not differ significantly between AGO (0.69 kg/d) and CON (0.62 kg/d) cattle (P = 0.18), although numerically higher ADG was observed in the AGO group. Enteric CH4 production was lower (P = 0.05) for AGO (162 g/d) compared to CON (178 g/d), while CO2 did not differ (P = 0.15) between treatments, but numeric differences were observed (6,120 g/d AGO vs 6,507 g/d CON). The numeric differences in performance and lower enteric CH4 emissions are reflected in the emission intensity results. AGO cattle demonstrated lower (P = 0.03) emissions intensity (243 g CH4/kg ADG) compared to CON cattle (293 g CH4/kg ADG). These findings suggest beneficial modulation of enteric emissions with Agolin, but further studies with larger sample sizes and optimal supplement intake are needed to confirm efficacy under grazing conditions.

Abstract Rising global temperatures have intensified the urgency to reduce greenhouse gas (GHG) emissions from anthropogenic sources, including agricultural methane (CH4). CH4 is a potent GHG produced as a byproduct of ruminal fermentation in cattle. CH4 warms the atmosphere 28 times more than carbon dioxide (CO₂) over a 100-year period, making it a critical GHG mitigation target. Multiple approaches are being developed, but the beef cattle industry lacks solutions that effectively reach ~80% of bovine CH4 emissions produced in extensive, pasture-based systems, e.g., the cow-calf and stocker segments. One promising approach is a methane-reducing vaccine. Methane-reducing vaccines stimulate the production of anti-methanogen antibodies. These antibodies potentially enter the rumen, bind to their methanogen targets, and inhibit ruminal methanogenesis, thereby reducing enteric CH4 emissions. The objective of this trial was to assess the effect of a proto-type vaccine on growth performances, gas flux, and feeding behavior in beef cattle. Thirty Angus crossbred steers (n = 30; 451 ± 11 kg) were blocked by body weight (BW) and stratified by breed before being randomly assigned to one of two treatments: control (n = 20) or vaccine-treated (n = 10). Animals received a prime-boost vaccine regimen (2 mL, each) administered subcutaneously on days 0 and 21. Animals were housed in three pens, each equipped with three electronic feed bunks (Vytelle, Lenexa, KS) for recording individual feed intake and feeding behavior, as well as one GreenFeed emission monitoring system (C-lock Inc., Rapid City, SD) for measuring CH4 emissions. Weekly BW, daily feed intake, and gas emissions were measured over an 84-day period. Statistical analyses were conducted in JMP Pro v.16 (SAS Institute Inc., Cary, NC), with individual animals as the experimental unit, and treatment as a fixed effect. There were no significant differences in average daily gain (ADG), initial BW, mid-test metabolic BW (BW⁰·⁷⁵), DMI, alfalfa pellet intake or gain: feed (P &amp;gt; 0.05). The vaccine-treated group had 15% lower (P = 0.0050) CH4 production (g/d), 18% lower (P = 0.0038), CH4 intensity (g/kg BW 0.75) and 13% lower (P = 0.0149) CH4 yield emissions (g/kg DMI) compared to the control. However, CO2 production (g/d), CO2 yield (g/kg DMI) and H2 production (g/d) did not differ (P &amp;gt; 0.05). Bunk visit (BV) duration was also similar between groups (P &amp;gt; 0.05). However, the vaccine-treated group had fewer BV per day (P = 0.0292) and a longer BV head-down duration per day (P = 0.0105), with a tendency for a slower eating rate (P = 0.0697) compared to control. These results highlight the potential of vaccination as a strategy to mitigate enteric CH4 production in beef cattle without negatively impacting growth performance.

Abstract Supplementation with non-protein nitrogen (NPN) has been used as an alternative to supply nitrogen in low-protein diets for ruminants. Urea is the primary source of NPN supplemented to cattle, but its rapid degradation rate in the rumen limits the inclusion level due to risks of ammonia toxicity. However, novel NPN formulations that include a mixture of urea and biuret (UB) result in lower degradation rates, which may allow for higher inclusion levels than urea alone. Thus, it was hypothesized that by using UB, the inclusion of NPN can be increased in beef cattle diets without impairing production efficiency or safety. The objective of this study was to evaluate urea supplementation at 1% and increasing inclusions of UB on beef steers performance and enteric methane (CH4) emissions. To this end, 128 Angus-crossbred steers were used in a generalized randomized block design. Treatments were composed of a corn-silage basal diet supplemented with urea at 1% of the diet dry matter (DM) (U1), or supplemented with UB at 1.12% (UB1), 2.24% (UB2), or 4.48% (UB4) of the diet DM. The experimental period consisted of 24 d of adaptation, followed by 86 d of performance data collection, and 5 d of enteric CH4 emissions measurements using the sulfur hexafluoride tracer technique. No differences in dry matter intake were observed among treatments (P = 0.41). The UB4 treatment decrease average daily gain (ADG) when compared with U1 (P = 0.05), while no differences were observed among U1, UB1 and UB2. Similarly, gain to feed ratio decreased for the UB4 treatment when compared with U (P = 0.005), though no differences were observed among U1, UB1 and UB2. Total CH4 emission rate (g/d) and CH4 intensity (g/kg ADG), were not affected by treatments (P &amp;gt; 0.05). In conclusion, UB supported equivalent performance to U, when included at 1.12% or 2.24% of the diet DM without compromising efficiency or increasing CH4 emissions. However, the highest inclusion level (4.48%) impaired feed efficiency. These results demonstrate that UB formulation allows NPN supplementation at higher dietary inclusion levels than conventional urea, thereby expanding the safety margin of NPN utilization in beef cattle diets.

Abstract Enteric methane (CH4) in ruminants might lead to losses of dietary gross energy, reducing production efficiency. Red seaweed contains bromoform, a chemical known for decreasing enteric CH4 emissions in ruminants. This study evaluated the effects of different inclusion levels (0, 1, 5, and 10%) of red seaweed Gracilaria spp. on in vitro fermentation parameters using ruminal fluid from two cannulated animals. Experiment 1 utilized a randomized complete block design (RCBD) with three replicates. Fixed effects were algae, inclusion level, and drying method, with incubation day as a random effect. Experiment 2 employed a RCBD with fixed effects of algae and inclusion level, and incubation day as a random effect. Polynomial contrasts (linear, quadratic, and cubic) were applied in both experiments. In experiment 1, G. mammillaris (GM) and G. damicornis (GD) were evaluated under two drying methods, sundried (SD) and freeze dried (FD). For pH, a positive linear effect was observed (P &amp;lt; 0.01) for GMSD, GDSD, and GDFD, and a quadratic effect (P &amp;lt; 0.03) for GMFD. A negative linear effect of algae inclusion was observed (P = 0.05) in GMFD and GDSD for CH4/g of dry matter (DM) incubated, and in GDSD for total volatile fatty acids (mM; P = 0.04). An interaction between algae spp. and drying method was observed for acetate molar proportions (MP; P = 0.04), with a linear increase for GMFD and GDSD (P = 0.01 and P = 0.04 respectively). Propionate MP decreased linearly for GMFD (P = 0.01) and the acetate to propionate ratio was higher for GMSD (P = 0.04) and GMFD (P &amp;lt; 0.01). Experiment 2 evaluated three Gracilaria spp.: G. mammillaris (GM), G. damicornis (GD), and G. coronopifolia (GC). Algae were snap-frozen with liquid nitrogen and subsequently freeze dried, prior to incubation. A negative linear effect in algae inclusion level was observed in total gas produced for GD (P = 0.03) and GC (P = 0.05). A linear decrease was observed in CH4/g of DM incubated for GD (P = 0.01) and GC (P = 0.01). This decrease persisted for CH4/g of OM fermented (P = 0.05) in both GD and GC. Acetate MP increased linearly with algae inclusion level for GD (P = 0.03), whereas propionate MP linearly decreased in GC (P = 0.03), and a cubic effect was observed for GD (P = 0.04). Inclusion of the Gracilaria spp. has the potential to reduce CH4 production; however, this reduction was not correlated with algae bromoform concentrations. Other compounds might have affected the fermentation, and they warrant further investigation. Snap freezing resulted in greater bromoform concentration regardless of drying method, indicating that harvesting method is an important aspect to manage during red algae production for CH4 mitigation.

Effects of methane inhibitors on ruminal fermentation and microbial composition in vitro using inoculum from phenotypically high- and low-enteric-methane-emitting cows.

Effects of various sources of unsaturated oil on ruminal fermentation characteristics, nutrient digestion, enteric methane emissions, nitrogen partitioning, and milk production in dairy cows.

Effect of fumarate and live yeast on ruminal fermentation, methane emissions, and blood metabolites in dairy goats.

A meta-analysis of effects of seaweed and other bromoform-containing feed ingredients on methane production, yield, and intensity in cattle.

Lactational performance and enteric methane emissions in dairy cows fed high-oil oats, cold-pressed rapeseed cake, and 3-nitrooxypropanol in a grass silage-based diet.

Improved prediction by enteric methane emission models in ruminant production systems by integrating climate classification.

Genetic parameters for enteric methane traits and their genetic connection with milk production in Danish Holstein cattle.