The Ability of Hop Extracts to Reduce the Methane Production of Methanobrevibacter ruminantium.

Infectious Diseases, Livestock, and Climate: A Vicious Cycle?

Over 1000 anaerobic ponds are used in the treatment of wastewater from farms and industry in New Zealand. These anaerobic ponds were typically designed as wastewater solids holding ponds rather than for treatment of the wastewater. However, visual observation of these uncovered ponds indicates year-round anaerobic digestion and release of biogas to the atmosphere. The release of biogas may be associated with odour nuisance, contributes to greenhouse gas (GHG) emissions and is a waste of potentially useful energy. The aim of this study was to measure the seasonal variation in quantity and quality of biogas produced by an anaerobic pond at a piggery (8000 pigs) and a dairy farm (700 cows). Biogas was captured on the surface of each anaerobic pond using a floating 25 m2 polypropylene cover. Biogas production was continually monitored and composition was analysed monthly. Annual average biogas (methane) production rates from the piggery and dairy farm anaerobic ponds were 0.84 (0.62) m3/m2.day and 0.032 (0.026) m3/m2.day, respectively. Average CH4 content of the piggery and dairy farm biogas was high (74% and 82%, respectively) due to partial scrubbing of CO2 within the pond water. The average daily volume of methane gas that could potentially be captured by completely covering the surface of the piggery and dairy farm anaerobic ponds was calculated as ~550 m3/day and ~45 m3/day, respectively (assuming that the areal methane production rate was uniform across the pond surface). Conversion of this methane to electricity would generate 1650 kWh/day and 135 kWh/day, respectively (with potentially 1.5 times these values co-generated as heat) and reduce GHG emissions by 8.27 t CO2 equivalents/day and 0.68 t CO2 equivalents/day, respectively. These preliminary results suggest that conventional anaerobic ponds in New Zealand may release considerable amounts of methane and could be a more significant point source of GHG emissions than previously estimated. Further studies of pond GHG emissions are required to accurately assess the contribution of wastewater treatment ponds to New Zealand’s total GHG emissions.

Methane emissions in ruminant livestock has become a hot topic, given the pressure to reduce greenhouse gas emissions drastically in the European Union over the next 10 to 30 yr. During the 2021 United Nations Climate Change conference, countries also made collective commitments to curb methane emissions by 2050. Genetic selection for low-methane-emitting animals, particularly dairy cows, is one possible strategy for mitigation. However, it is essential to understand how methane emissions in lactating animals vary along lactation and across lactations. This understanding is useful when making decisions for future phenotyping strategies, such as the frequency and duration of phenotyping within and across lactations. Therefore, the objectives of this study were to estimate (1) genetic parameters for 2 methane traits: methane concentration (MeC) and methane production (MeP) at 2 parity levels in Danish Holstein cows across the entire lactation using random regression models; (2) genetic correlations within and between methane traits across the entire lactation; and (3) genetic correlations between the methane traits and economically important traits throughout first lactation. Methane concentration (n = 19,639) records of 575 Danish Holstein cows from a research farm measured between 2013 and 2020 were available. Subsequently, CH4 production in grams/day (MeP; n = 13,866) was calculated; MeP and MeC for first and second lactation (L1 and L2) were analyzed as separate traits: MeC_L1, MeP_L1, MeC_L2, and MeP_L2. Heritabilities, variance components, and genetic correlations within and between the 4 CH4 traits were estimated using random regression models with Legendre polynomials. The additive genetic and permanent environmental effects were modeled using second-order Legendre polynomial for lactation weeks. Estimated heritabilities for MeP_L1 ranged between 0.11 and 0.49, for MeC_L1 between 0.10 and 0.28, for MeP_L2 between 0.14 and 0.36, and for MeC_L2 between 0.13 and 0.29. In general, heritability estimates of MeC traits were lower and more stable throughout lactation and were similar between lactations compared with MeP. Genetic correlations (within trait) at different lactation weeks were generally highly positive (0.7) for most of the first lactation, except for the correlation of early lactation (<10 wk) with late lactation (>40 wk) where the correlation was the lowest (<0.5). Genetic correlations between methane traits were moderate to highly correlated during early and mid lactation. Finally, MeP_L1 has stronger genetic correlations with energy-corrected milk and dry matter intake compared with MeC_L1. In conclusion, both traits are different along (and across) lactation(s) and they correlated differently with production, maintenance, and intake traits, which is important to consider when including one of them in a future breeding objective.

Editorial: Feeding and Nutritional Strategies to Reduce Livestock Greenhouse Gas Emissions.

Simple SummaryAn important strategy to mitigate global warming is to reduce methane produced by ruminants. However, the inhibition of rumen methanogenesis generally results in hydrogen accumulation, which would affect the normal fermentation in the rumen. In this study, we used a combination of two chemicals (fumarate and nitroglycerin) to mitigate the rumen methane production. Nitroglycerin inhibits the activities of methanogens. Fumarate eliminates hydrogen accumulation. In vitro rumen fermentation was used to investigate the effects of this combination on rumen fermentation, methane and hydrogen production, and microbiota. The results showed that the addition of fumarate decreased the hydrogen accumulation and increased the concentration of propionate and microbial crude protein when methanogen activities were inhibited by nitroglycerin. The bacterial and archaeal communities were altered by the addition of the two chemicals, with several taxa changed in the relative abundance. Conclusively, the combination of fumarate and nitroglycerin inhibited methane production, reduced hydrogen accumulation, improved rumen fermentation and altered rumen microbiota. This study provides an alternative way of using these chemicals in order to mitigate methane emission in ruminants.This study aimed to investigate the effects of fumarate and nitroglycerin on rumen fermentation, methane and hydrogen production, and microbiota. In vitro rumen fermentation was used in this study with four treatment groups: control (CON), fumarate (FA), nitroglycerin (NG) and fumarate plus nitroglycerin (FN). Real-time PCR and 16S rRNA gene sequencing were used to analyze microbiota. The results showed that nitroglycerin completely inhibited methane production and that this resulted in hydrogen accumulation. Fumarate decreased the hydrogen accumulation and improved the rumen fermentation parameters. Fumarate increased the concentration of propionate and microbial crude protein, and decreased the ratio of acetate to propionate in FN. Fumarate, nitroglycerin and their combination did not affect the abundance of bacteria, protozoa and anaerobic fungi, but altered archaea. The PCoA showed that the bacterial (Anosim, R = 0.747, p = 0.001) and archaeal communities (Anosim, R = 0.410, p = 0.005) were different among the four treatments. Compared with CON, fumarate restored Bacteroidetes, Firmicutes, Spirochaetae, Actinobacteria, Unclassified Ruminococcaceae, Streptococcus, Treponema and Bifidobacterium in relative abundance in FN, but did not affect Succinivibrio, Ruminobacter and archaeal taxa. The results indicated that fumarate alleviated the depressed rumen fermentation caused by the inhibition of methanogenesis by nitroglycerin. This may potentially provide an alternative way to use these chemicals to mitigate methane emission in ruminants.

A study was conducted to examine in vitro ruminal fermentation profiles and methane production of some alternative forage species (n = 10) in Australia. Extent of fermentation was assessed using an in vitro batch fermentation system, where total gas production, methane production, and concentrations in ruminal fluid of volatile fatty acids (VFA) and ammonia were measured. Forages varied in their fermentability, with highest total gas, methane, VFA and ammonia production recorded from selected samples of Brassica napus L. cv. Winfred. Lowest methane production (i.e. 30% less than that formed by the highest-producing one) was observed in Plantago lanceolata L. cv. Tonic and Cichorium intybus L. cv. Choice. Selected plants, including P. lanceolata L. cv. Tonic, Brassica rapa L. cv. Marco, Brassica napus L. cv. Hunter had reduced acetate : propionate ratio and/or ammonia concentration, along with relatively low methane production compared with other species tested, while overall fermentation was not affected. It was concluded that selected novel forages have some advantageous fermentability profiles in the rumen and, in particular, inhibit methane production. However, before these can be recommended as valuable supplementary feedstuffs for ruminants in Australia, further studies are needed to confirm these effects over a range of samples, conditions and in vivo.

A meta-analysis study was conducted to investigate the changes in rumen fermentation characteristics when methane inhibition by phytochemicals is employed. The whole database containing 185 treatment means from 36 published studies was divided into four subsets according to the major phytochemicals used in the studies, i.e. saponins, tannins, essential oils (EO) and organosulfur compounds (OS). Changes in protozoal numbers showed linear relationships with changes in methane production by saponins (R(2) = 0.48), tannins (R(2) = 0.30) and EO (R(2) = 0.20) but not OS. Concentrations of total volatile fatty acids (VFA) and acetate did not show any relationship (P > 0.1) with changes in methane due to saponins. However, propionate production increased linearly with increasing inhibition of methane (R(2) = 0.31), which resulted in a linear (R(2) = 0.26) decrease in acetate/propionate ratio (A/P) with decreasing methane production. Concentrations of total VFA, acetate and propionate did not change with changes in methane production by tannins. However, A/P showed a significant linear relationship (R(2) = 0.27) with decreasing methane formation. Concentrations of total VFA (R(2) = 0.44) and propionate (R(2) = 0.15) changed linearly and positively with changes in methane production by EO. However, acetate production (R(2) = 0.22) and A/P (R(2) = 0.17) increased linearly with increasing inhibition of methane by EO. Changes in concentrations of total VFA (R(2) = 0.60) and acetate (R(2) = 0.35) decreased linearly while those of propionate increased linearly (R(2) = 0.23) with increasing inhibition of methane by OS. Consequently, A/P decreased linearly (R(2) = 0.30) with decreasing methane production by OS. Digestibilities of organic matter (OM) and neutral detergent fibre were not affected by inhibition of methane production by saponins, EO and OS, but digestibility of OM decreased with decreasing methane production by tannins. The inhibition of methane production by phytochemicals results in changes in rumen fermentation that differ depending on the types of phytochemicals.

Ruminants are the main contributor to agricultural emissions of the greenhouse gas methane (CH4), which is one of the main greenhouses causing global warming. The objective of this pilot study was to test the effectiveness of 4 different vaccine formulations (VF) on methane abatement in beef cattle. Two weeks before the start of the trial, steers aged between 9 to 10 months with body weights (236.57 ± 20,61 kg) were trained to use the GreenFeed (C-Lock Inc., Rapid City, SD, USA) system for methane measurement. At the end of the adaptation period, animals that best accepted the GreenFeed system were selected (n = 20) for the experiment. Animals were randomly assigned to one of four different formulations of vaccine treatments as well as a control group. Each treatment group had the following number of steers: Control/Untreated (UTD, n = 4), F1/OVA_ adj (n= 4), F2/Ag1_adj (n= 4), F3/pep1_Ag1_adj (n = 4), F4/pep2_Ag1_adj (n = 4). On day 0, vaccine was administered followed by booster injections on day 20 with 2mL injected intramuscularly in the anterior region of the neck both times. Through jugular venipuncture, blood was collected into a 10 mL vacutainer tube (Becton Drive, Franklin Lakes, NJ) to obtain serum on day 34 post-treatment to determine methanogen-specific IgA and IgG concentration. Rumen fluid (14 mL) was collected on pre-treatment (d0), and post treatments (d 20 and d 34) into a glass jar using an esophageal stomach tube connected to a vacuum and occurred pre-feeding to determine the relative abundance of total archaea and Methanobrevibacter ruminantium. Methane production was sampled on individual animals using the GreenFeed system pre-treatment (d -8 to -1) and post treatment (d 22 to d 29). The GreenFeed system estimates daily methane production (DMP, g/day) by measuring gas concentration for 3 to 5 mins on individual animals. Data were analyzed as one-way ANOVA with Tukey’s HSD post-hoc analysis. Preliminary results showed overall mean methane emission pre-treatment (165.853 ± 2.69 g/d) compared with post-treatment (192.164 ± 2.33 g/d) increased by 16%. However, methane emissions between treatment groups showed statistical difference (P &amp;lt; 0.001) specifically between treatment group F2 and F4. Serum concentration of IgA and IgG, ruminal relative abundance of total archaea and Methanobrevibacter ruminantium did not show significant difference (P &amp;gt; 0.10). From the results, vaccine formulation F2 and F4 showed effects in the methane emission between the treatment groups. Future research will consider increasing the vaccine dosage and analyzing more samples. This project was supported by HelixNano.

Methanogenesis, the microbial methane (CH4 ) production, is traditionally thought to anchor the mineralization of organic matter as the ultimate respiratory process in deep sediments, despite the presence of oxidized mineral phases, such as iron oxides. This process is carried out by archaea that have also been shown to be capable of reducing iron in high levels of electron donors such as hydrogen. The current pure culture study demonstrates that methanogenic archaea (Methanosarcina barkeri) rapidly switch from methanogenesis to iron-oxide reduction close to natural conditions, with nitrogen atmosphere, even when faced with substrate limitations. Intensive, biotic iron reduction was observed following the addition of poorly crystalline ferrihydrite and complex organic matter and was accompanied by inhibition of methane production. The reaction rate of this process was of the first order and was dependent only on the initial iron concentrations. Ferrous iron production did not accelerate significantly with the addition of 9,10-anthraquinone-2,6-disulfonate (AQDS) but increased by 11-28% with the addition of phenazine-1-carboxylate (PCA), suggesting the possible role of methanophenazines in the electron transport. The coupling between ferrous iron and methane production has important global implications. The rapid transition from methanogenesis to reduction of iron-oxides close to the natural conditions in sediments may help to explain the globally-distributed phenomena of increasing ferrous concentrations below the traditional iron reduction zone in the deep 'methanogenic' sediment horizon, with implications for metabolic networking in these subsurface ecosystems and in past geological settings.

Policy implications of liquefied natural gas use in heavy-duty vehicles: Examples in Canada and British Columbia

Methane production and emission in surface and subsurface rice soils and their blends

Automated machine learning-based prediction of microplastics induced impacts on methane production in anaerobic digestion

Methane production has been measured from lambs fed contrasting forages. This work has been driven by the need to reduce greenhouse gas emissions from agriculture and to determine energy losses to methane from contrasting diets. Young ram lambs were fed either fresh ryegrass/white clover pasture, lucerne (also pelleted lucerne), sulla, chicory, red clover, Lotus pedunculatus (lotus) and mixtures of sulla and lucerne, sulla and chicory and chicory with red clover. The effects of condensed tannin (CT) in lotus on methane production were also measured. The trials were carried out indoors with sheep held in metabolism crates to enable an accurate measurement of intake and digestibility as well as methane production. Principal findings were a two-fold range in emissions from 11.5g CH4/kg dry matter intake (DMI) with lotus to 25.7g CH4/kg DMI with pasture and a 16% reduction in methane production due to the CT in lotus. This range in emissions from good quality forages represents a loss of about 7-11% of metabolisable energy and presents a clear direction for future research to better utilise the feeding value of pastures and reduce greenhouse gas (GHG) emissions from agriculture. High quality perennial forages should be used where practical, and researchers need to identify plant parameters responsible for the variation in methane emissions. Research must focus on rapid passage of digesta through the rumen of grazing animals and will involve manipulation of the fibre content of grasses. Introduction of CT into diets is a likely target to reduce methane production. Improving the rapidly digestible constituents of forages is another opportunity, but difficult to target. Keywords: condensed tannins, forage quality, forages, greenhouse gases, methane emissions, sheep

Importance of reducing GHG emissions in power transmission and distribution systems

Ruminants contribute 80% of the global livestock greenhouse gas (GHG) emissions mainly through the production of methane, a byproduct of enteric microbial fermentation primarily in the rumen. Hence, reducing enteric methane production is essential in any GHG emissions reduction strategy in livestock. Data on 1,046 young bulls and heifers from 2 performance-recording research herds of Angus cattle were analyzed to provide genetic and phenotypic variance and covariance estimates for methane emissions and production traits and to examine the interrelationships among these traits. The cattle were fed a roughage diet at 1.2 times their estimated maintenance energy requirements and measured for methane production rate (MPR) in open circuit respiration chambers for 48 h. Traits studied included DMI during the methane measurement period, MPR, and methane yield (MY; MPR/DMI), with means of 6.1 kg/d (SD 1.3), 132 g/d (SD 25), and 22.0 g/kg (SD 2.3) DMI, respectively. Four forms of residual methane production (RMP), which is a measure of actual minus predicted MPR, were evaluated. For the first 3 forms, predicted MPR was calculated using published equations. For the fourth (RMP), predicted MPR was obtained by regression of MPR on DMI. Growth and body composition traits evaluated were birth weight (BWT), weaning weight (WWT), yearling weight (YWT), final weight (FWT), and ultrasound measures of eye muscle area, rump fat depth, rib fat depth, and intramuscular fat. Heritability estimates were moderate for MPR (0.27 [SE 0.07]), MY (0.22 [SE 0.06]), and the RMP traits (0.19 [SE 0.06] for each), indicating that genetic improvement to reduce methane emissions is possible. The RMP traits and MY were strongly genetically correlated with each other (0.99 ± 0.01). The genetic correlation of MPR with MY as well as with the RMP traits was moderate (0.32 to 0.63). The genetic correlation between MPR and the growth traits (except BWT) was strong (0.79 to 0.86). These results indicate that selection for lower MPR may have undesired effect on animal productivity. On the other hand, MY and the RMPR were either not genetically correlated or weakly correlated with BWT, YWT, and FWT (-0.06 to 0.23) and body composition traits (-0.18 to 0.18). Therefore, selection for lower MY or RMPR would lead to lower MPR without impacting animal productivity. Where the use of a ratio trait (e.g., MY) is not desirable, selection on any of the forms of RMP would be an alternative.