Assessment of the in situ biomethanation potential of a deep aquifer used for natural gas storage.

The dihydrogen (H2) sector is undergoing development and will require massive storage solutions. To minimize costs, the conversion of underground geological storage sites, such as deep aquifers, used for natural gas storage into future underground hydrogen storage sites is the favored scenario. However, these sites contain microorganisms capable of consuming H2, mainly sulfate reducers and methanogens. Methanogenesis is, therefore expected but its intensity must be evaluated. Here, in a deep aquifer used for underground geological storage, 17 sites were sampled, with low sulfate concentrations ranging from 21.9 to 197.8 µM and a slow renewal of formation water. H2-selected communities mainly were composed of the families Methanobacteriaceae and Methanothermobacteriaceae and the genera Desulfovibrio, Thermodesulfovibrio, and Desulforamulus. Experiments were done under different conditions, and sulfate reduction, as well as methanogenesis, were demonstrated in the presence of a H2 or H2/CO2 (80/20) gas phase, with or without calcite/site rock. These metabolisms led to an increase in pH up to 10.2 under certain conditions (without CO2). The results suggest competition for CO2 between lithoautotrophs and carbonate mineral precipitation, which could limit microbial H2 consumption.

In vitro assessment of ruminal biohydrogenation of polyunsaturated fatty acids in diets with different types and levels of protected fat and diverse sources of fibre.

The objective was to assess the in vitro rumen fermentation characteristics, methane production, and biohydrogenation of unsaturated fatty acids of diets with two protected fat (PF) sources from soybean or linseed oil, two levels of PF (0 and 6%) and two forage sources (canola silage (CS) or alfalfa hay (AH)) in a factorial 2x2x2 completely randomised design. Only fatty acids content at final incubation was affected (P<0.05) by triple interaction, where C18:2 was highest with AH plus 6% soybean PF (4.41mg/g DM), while C18:3 was with CS plus 6% linseed oil protected (1.98mg/g DM). C18:2 cis-9 trans-11 had high concentration (308 mg/g DM; P<0.05) with AH plus 6% PF regardless PF type, and C18:1 trans-11 was higher with 6% PF than without PF (13.41 vs 7.89 mg/g DM). Cumulative methane production was not affected by treatments (0.9973 ± 0.1549 mmol/g DM; P>0.05). Gas production and in vitro NDF digestibility were lower with 6% PF of linseed than soybean (160.88 vs 150.97 ml; and 69.28vs 62.89 %, respectively P<0.05). With linseed PF the NH3-N concentration was highest in CS than AH (41.27 vs 27.95 mg/dL; P<0.05) but IVDMD had the opposite result (78.54 vs 85.04). In conclusion, although methane production was not affected and in vitro digestibility and gas production were reduced with linseed PF, the concentration of C18:3 and C18:1 trans-11 was increased, which could improve the lipid profile of milk. The negative effects on digestibility were less with AH than of CS regardless of PF type and level.

Exploring increased hydraulic retention time as a cost-efficient way of valorizing residual biogas potential.

Effective substrate utilization with low residual methane yield in the digestate is crucial for the economy and sustainability of biogas plants. The composition and residual methane potential of 29 digestate samples from plants operating at hydraulic retention times of 13-130 days were determined to evaluate the economic viability of extended digestion. Considerable contents of fermentable fractions, such as cellulose (8-23%), hemicellulose (1-18%), and protein (13-22%), were present in the digestate dry matter. The ultimate residual methane yields varied between 55 and 236 ml/g of volatile solids and correlated negatively with the logarithm of the hydraulic retention time (r = -0.64, p < 0.05). Economic analysis showed that extending the retention time in 20 days would be viable for 18 systems if methane were sold for 1.00 €/m3, with gains up to 40 €/year/m3 of newly installed reactor capacity. The results show the importance of operating at sufficient hydraulic retention time.

Assessment of biodegradability of cellulose and poly(butylene succinate)-based bioplastics under mesophilic and thermophilic anaerobic digestion with a view towards biorecycling.

Despite the increasing interest in bioplastics, there are still contradictory results on their actual biodegradability, which cause difficulties in choosing and developing appropriate sustainable treatment methods. Two biofoils (based on poly(butylene succinate) (PBS37) and cellulose (Cel37)) were anaerobically degraded during 100-day mesophilic (37 °C) and thermophilic (55 °C) tests (PBS55, Cel55). To overcome low degradation rates in mesophilic conditions, alkaline pre-treatment was also used (Pre-PBS37, Pre-Cel37). For comprehensive understanding of biodegradability, not only methane production (MP), but also the structure (topography, microscopic analysis), tensile properties, and FTIR spectra of the materials undergoing anaerobic degradation (AD) analysed. PBS37 and Pre-PBS37 were visible in 100-day degradation, and the cumulative MP reached 25.5 and 29.3 L/kg VS, respectively (4.3-4.9% of theoretical MP (TMP)). The biofoils started to show damage, losing their mechanical properties over 35 days. In contrast, PBS55 was visible for 14 days (cracks and fissures appeared), cumulative MP was 180.2 L/kg VS (30.2% of the TMP). Pieces of Cel were visible only during 2 days of degradation, and the MP was 311.4-315.0 L/kg VS (77.3-78.2% of the TMP) at 37 °C and 319.5 L/kg VS (79.3% of the TMP) at 55 °C. The FTIR spectra of Cel and PBS did not show shifts and formation of peaks. These findings showed differences in terms of the actual biodegradability of the bioplastics and provided a deeper understanding of their behaviour in AD, thus indicating limitations of AD as the final treatment of some materials, and also may support the establishment of guidelines for bioplastic management.

Impact of primary treatment methods on sludge characteristics and digestibility, and wastewater treatment plant-wide economics.

Biogas production from anaerobic sludge digestion plays a central role for wastewater treatment plants to become more energy-efficient or even energy-neutral. Dedicated configurations have been developed to maximize the diversion of soluble and suspended organic matter to sludge streams for energy production through anaerobic digestion, such as A-stage treatment or chemically enhanced primary treatment (CEPT) instead of primary clarifiers. Still, it remains to be investigated to what extent these different treatment steps affect the sludge characteristics and digestibility, which may also impact the economic feasibility of the integrated systems. In this study, a detailed characterization has been performed for sludge obtained from primary clarification (primary sludge), A-stage treatment (A-sludge) and CEPT. The characteristics of all sludges differed significantly from each other. The organic compounds in primary sludge consisted mainly of 40% of carbohydrates, 23% of lipids, and 21% of proteins. A-sludge was characterized by a high amount of proteins (40%) and a moderate amount of carbohydrates (23%), and lipids (16%), while in CEPT sludge, organic compounds were mainly 26% of proteins, 18% of carbohydrates, 18% of lignin, and 12% of lipids. The highest methane yield was obtained from anaerobic digestion of primary sludge (347 ± 16 mL CH4/g VS) and A-sludge (333 ± 6 mL CH4/g VS), while it was lower for CEPT sludge (245 ± 5 mL CH4/g VS). Furthermore, an economic evaluation has been carried out for the three systems, considering energy consumption and recovery, as well as effluent quality and chemical costs. Energy consumption of A-stage was the highest among the three configurations due to aeration energy demand, while CEPT had the highest operational costs due to chemical use. Energy surplus was the highest by the use of CEPT, resulting from the highest fraction of recovered organic matter. By considering the effluent quality of the three systems, CEPT had the highest benefits, followed by A-stage. Integration of CEPT or A-stage, instead of primary clarification in existing wastewater treatment plants, would potentially improve the effluent quality and energy recovery.

Controlling air pollution by lowering methane emissions, conserving natural resources, and slowing urbanization in a panel of selected Asian economies.

The destruction of the earth's ecosystems is the most pressing issue globally. Carbon emissions account for nearly half of global air pollution. Methane is the primary source of ground-level ozone and a significant source of greenhouse gases (GHGs), with greater warming potential than carbon dioxide emissions. The study examines the impact of the different methane emissions (released by agriculture, energy, and industrial sectors), urbanization, natural resource depletion, and livestock production on carbon emissions in the panel of selected Asian countries for the period of 1971 to 2020. The results show that energy associated methane emissions, livestock production, natural resource depletion, and urbanization are the main detrimental factors of environmental degradation across countries. The causality estimates show the unidirectional relationship running from livestock production and agriculture methane emissions to carbon emissions, from total methane emissions and carbon emissions to urbanization and from urbanization to energy methane emissions and livestock production. The forecasting estimates suggest that total methane emissions, natural resource depletion, and urbanization will likely increase carbon emissions over the next ten years. The study concludes that the energy sector should adopt renewable energy sources in its production process to minimize carbon emissions. Urbanization and excessive resource exploitation must be curtailed to attain carbon neutrality.

In vitro fermentation and production of methane and carbon dioxide from rations containing Moringa oleifera leave silage as a replacement of soybean meal: in vitro assessment.

Plant leaf meal of some forage trees such as Moringa oleifera has attracted an increasing interest as a good and cheap source of protein. The present in vitro experiment employed the in vitro wireless gas production (GP) technique to evaluate the inclusion of M. oleifera leaves ensiled for 45 days as a replacement for soybean meal in rations. A control basal ration was formulated to contain 17.5% soybean meal as a source of protein. Soybean meal in the control ration was replaced with silage (MOS) at increasing levels of 0 to 100%. Replacing soybean meal with MOS gradually increased (P < 0.001) GP kinetics (asymptotic GP, rate of GP, and lag time of GP). However, soybean meal replacement decreased (P < 0.001) asymptotic methane (CH4) and carbon dioxide (CO2) productions, and rate of CH4 production and increased the lag time of CH4 and CO2 production. Gradual increases (P < 0.001) in the digestibility of dry matter, neutral detergent fiber and acid detergent fiber, ruminal bacteria count, fermentation pH, and the concentrations of ruminal total volatile fatty acids, acetate, and propionate were observed with rations containing MOS. Decreases in the digestibility of crude protein, ruminal protozoal count, and the concentrations of ruminal ammonia-N were observed with MOS rations. It is concluded soybean meal can be completely replaced by MOS with desirable effects on ruminal fermentation.

Productive, economic, and environmental effects of sunflower (Helianthus annuus) silage for dairy cows in small-scale systems in central Mexico.

Small-scale dairy systems (SSDS) are important source of livelihood and socio-economic wellbeing for the rearers in general. The reduction of methane emissions with the inclusion of sunflower seed or seed-meal in rations for dairy cows has been reported in several studies. However, studies pertaining to the use of sunflower silage in dairy cattle feeding are lacking. The present study was conducted to assess the productive, economic, and environmental effects of the inclusion of graded levels of sunflower silage at 0%, 20%, 40%, and 60% (SFSL) along with maize silage (MZSL) on a dry matter basis. The silage was provided to eight Holstein cows in two 4×4 Latin-squares with 14-day periods. The study encompassed the productive performance of the cows, composition of feeds, besides the feeding costs, and enteric methane emissions estimated. The study indicated that inclusion of SFSL in the diet enhanced (P<0.001) the FCM by 3.5% and milk-fat content. SFSL increased feeding costs, but income/feeding costs ratios did not differ across the treatments. The higher inclusion of SFSL reduced methane emissions/kg of DM intake, / kg of milk, and in energy lost as methane. The inclusion of sunflower silage in feeding strategies for cows may be a viable alternative by increasing their milk yields and milk fat content and reducing methane emissions without affecting the income/feeding costs ratios.

Effects of operating conditions on biogas production in an anaerobic digestion system of the food and beverage industry.

BACKGROUND: Food residuals (FR) were anaerobically biotransformed to produce biogases (e.g. methane and hydrogen), and different pre-treatment conditions, including particle size, oil content, pH and salt content, were controlled in this study. The bio-solids of a municipal solid waste (MSW) from a wastewater treatment plant were added to assess its effect on anaerobic transformation efficiency and gas yields. RESULTS: The breaking of FR and the application of MSW were effective in enhancing the transformation efficiency and yield of biogases. The energy transfer efficiency value of the combined FRs used in this study was probably 23%. However, it can be very cost effective to apply arbitrary proportions to treat two types of FR in the anaerobic digestion tank of a wastewater treatment plant. It was also found that the alkalinity and pH value were two major parameters that controlled the success of the transformation. About 0.16-0.17 kg of alkalinity was needed during the anaerobic digestion of 1 kg dry FR, but this requirement was decreased by the treatment applying MSW. Olive oil had higher reducing rates when used as a substitute for heat-oxidized oil to study the effect of oil content on methylation. CONCLUSION: The conditions for anaerobic digestion established in this study were practical for the digestion of FR in wastewater treatment plants in Taiwan. However, we nonetheless found that it was cost effective to use arbitrary proportions for both types of FR and integrate the anaerobic digestion process used in wastewater treatment plants. © 2020 Society of Chemical Industry.

Milk production and estimated enteric methane emission from cows grazing ryegrass pastures in small-scale dairy systems in Mexico.

The work assessed the productive response and estimated enteric methane (CH4) emissions of dairy cows grazing in small-scale dairy systems. Treatments were grazing annual pasture (AP) mainly of annual ryegrass and perennial pasture (PP) mainly of perennial ryegrass, complemented daily with 3.72 kg DM/cow of commercial concentrate. Eight Holstein cows were used in a double cross-over design with three 14-day-each experimental periods for animal variables and CH4 emissions. Pasture variables were analysed with a split-plot design. AP showed higher sward height (P < 0.05) with no differences (P > 0.05) in net herbage accumulation or in herbage chemical composition. Cows on AP yielded 24.6% more milk (P < 0.001) than grazing PP, but there were no differences in milk fat and protein content. There were differences (P ≤ 0.05) among periods for milk yields, but no differences among periods for milk fat and protein. Milk urea nitrogen was significantly higher (P < 0.001) in PP than in AP with no differences among periods. There was higher (P < 0.001) DMI for AP than PP with a significant decline (P < 0.05) as periods progressed. There was a trend (P = 0.08) for higher daily CH4/cow in AP, but significantly lower emissions (7.2%) in AP/kg DMI, and 20.1% lower emission intensity of g CH4/kg milk. The proportion of gross energy lost as CH4 for AP was lower (P < 0.01). Higher milk yields in AP resulted in a 26% higher margin over feed costs than for PP. Results show that grazing annual pastures with moderate concentrate supplementation results in higher milk yields, higher incomes, and reduces the intensity of CH4 emissions.

Mitigation of greenhouse gases in dairy cattle via genetic selection: 2. Incorporating methane emissions into the breeding goal.

The objective of this study was to analyze the impact of incorporating enteric methane into the breeding objective of dairy cattle in Spain, and to evaluate both genetic and economic response of traits in the selection index under 4 scenarios: (1) the current ICO (Spanish total merit index), used as benchmark; (2) a hypothetical penalization of methane emissions through a carbon tax; (3) considering methane as a net energy loss for the animal; and (4) desired genetic response to reduce methane production by 20% in 10 yr. A bio-economic model was developed to derive the economic values for production and methane traits in each scenario. The estimated economic values for methane were estimated at -€1.21/kg and -€0.32/kg for scenarios 2 and 3, respectively. When merged with other traits in the selection index, methane had less economic importance (1-5%) than milk protein yield (39-42%) or milk fat yield (27-28%). Under these scenarios, selection resulted in an unfavorable response in methane emissions when it was included with an economic weight, with an increase in methane estimated from 0.52 to 0.60 kg/cow per year. Small differences in total profit per cow per year were observed between indices. The incorporation of methane production into the breeding objective had a negligible effect on production, with minor reductions in the expected genetic gain for fat and protein yields and in total economic benefits. However, total methane emissions in the dairy industry in Spain were estimated to decrease between 2 and 5% in the next 10 yr due to positive genetic trends for milk yield and an expected decrease in the total number of dairy cows. Additionally, methane intensity per 1 billion liters of milk would decrease in all scenarios. The uncertainty in the genetic parameters of methane and in carbon prices were tested in a sensitivity analysis, resulting in small deviations from the benchmark scenario. A major effect was observed only under the desired genetic response scenario. In this case, it was possible to achieve a 20% reduction of methane production in 10 yr via selective breeding but at the expense of a larger ad hoc weight (33%) of methane in the selection index and decelerating the genetic gain for production traits from 6 to 18%. This study shows the potential of including environmental traits in the selection indices while retaining populations profitable for producers.

Profitability, energetics and GHGs emission estimation from rice-based cropping systems in the coastal saline zone of West Bengal, India.

This study compares thirteen rice-based cropping systems in the coastal part of West Bengal, India in terms of productivity, profitability, energetics, and emissions. Information on the crop management practices of these systems was collected on 60 farms through a questionnaire survey. Rice-bitter gourd system was observed to have the highest system yield (49.88 ± 4.34 tha-1yr-1) followed by rice-potato-ridge gourd (37.78 ± 2.77 tha-1yr-1) and rice-potato-pumpkin (36.84 ± 2.04 tha-1yr-1) systems. The rice-bitter gourd system also recorded the highest benefit:cost ratio (3.92 ± 0.061). The lowest system yield and economics were recorded in the rice-fallow-fallow system. Rice-sunflower system recorded highest specific energy (2.54 ± 0.102 MJkg-1), followed by rice-rice (2.14 ± 0.174 MJkg-1) and rice-fallow-fallow (1.91 ± 0.327 MJkg-1) systems, lowest being observed in the rice-bitter gourd (0.52 ± 0.290 MJkg-1) and rice-pointed gourd (0.52 ± 0.373 MJkg-1) systems. Yield-scaled GHGs (YSGHG) emission was highest (1.265 ± 0.29 t CO2eqt-1 system yield) for rice-fallow-fallow system and was lowest for rice-vegetable systems. To estimate the uncertainty of the YSGHG across different systems under study, Monte-Carlo Simulation was performed. It was observed that there was a 5% probability of recording YSGHG emission > 1.15 t CO2eqt-1 system yield from different cropping systems in the present experiment. Multiple system properties such as productivity, economics, energy, and emission from all rice-based systems taken together, the rice-vegetable system performed consistently well across parameters and may be practised for higher economic returns with judicious and sustainable utilization of resources in the coastal saline tracts of the region.

Measured greenhouse gas budgets challenge emission savings from palm-oil biodiesel.

The potential of palm-oil biofuels to reduce greenhouse gas (GHG) emissions compared with fossil fuels is increasingly questioned. So far, no measurement-based GHG budgets were available, and plantation age was ignored in Life Cycle Analyses (LCA). Here, we conduct LCA based on measured CO2, CH4 and N2O fluxes in young and mature Indonesian oil palm plantations. CO2 dominates the on-site GHG budgets. The young plantation is a carbon source (1012 ± 51 gC m-2 yr-1), the mature plantation a sink (-754 ± 38 gC m-2 yr-1). LCA considering the measured fluxes shows higher GHG emissions for palm-oil biodiesel than traditional LCA assuming carbon neutrality. Plantation rotation-cycle extension and earlier-yielding varieties potentially decrease GHG emissions. Due to the high emissions associated with forest conversion to oil palm, our results indicate that only biodiesel from second rotation-cycle plantations or plantations established on degraded land has the potential for pronounced GHG emission savings.

The hydrogen gas bio-based economy and the production of renewable building block chemicals, food and energy.

The carrying capacity of the planet is being exceeded, and there is an urgent need to bring forward revolutionary approaches, particularly in terms of energy supply, carbon emissions and nitrogen inputs into the biosphere. Hydrogen gas, generated by means of renewable energy through water electrolysis, can be a platform molecule to drive the future bioeconomy and electrification in the 21st century. The potential to use hydrogen gas in microbial metabolic processes is highly versatile, and this opens a broad range of opportunities for novel biotechnological developments and applications. A first approach concerns the central role of hydrogen gas in the production of bio-based building block chemicals using the methane route, thus, bypassing the inherent low economic value of methane towards higher-value products. Second, hydrogen gas can serve as a key carbon-neutral source to produce third-generation proteins, i.e. microbial protein for food applications, whilst simultaneously enabling carbon capture and nutrient recovery, directly at their point of emission. Combining both approaches to deal with the intermittent nature of renewable energy sources maximises the ability for efficient use of renewable resources.

Determining the economic value of daily dry matter intake and associated methane emissions in dairy cattle.

Feed represents a substantial proportion of production costs in the dairy industry and is a useful target for improving overall system efficiency and sustainability. The objective of this study was to develop methodology to estimate the economic value for a feed efficiency trait and the associated methane production relevant to Canada. The approach quantifies the level of economic savings achieved by selecting animals that convert consumed feed into product while minimizing the feed energy used for inefficient metabolism, maintenance and digestion. We define a selection criterion trait called Feed Performance (FP) as a 1 kg increase in more efficiently used feed in a first parity lactating cow. The impact of a change in this trait on the total lifetime value of more efficiently used feed via correlated selection responses in other life stages is then quantified. The resulting improved conversion of feed was also applied to determine the resulting reduction in output of emissions (and their relative value based on a national emissions value) under an assumption of constant methane yield, where methane yield is defined as kg methane/kg dry matter intake (DMI). Overall, increasing the FP estimated breeding value by one unit (i.e. 1 kg of more efficiently converted DMI during the cow's first lactation) translates to a total lifetime saving of 3.23 kg in DMI and 0.055 kg in methane with the economic values of CAD $0.82 and CAD $0.07, respectively. Therefore, the estimated total economic value for FP is CAD $0.89/unit. The proposed model is robust and could also be applied to determine the economic value for feed efficiency traits within a selection index in other production systems and countries.

Environmental impact and economic sustainability analysis of a novel anaerobic digestion waste-to-energy pilot plant in Pakistan.

A novel medium-large industrial-scale, anaerobic digestion (AD) waste-to-energy pilot plant has been investigated in terms of cost-benefit, environmental impact, and economic sustainability. This pilot plant exclusively features a multi-digester AD system induced by motorized stirring, methane purification, compression, storage and digestate-fertilizer processing systems, and subsequent electricity generation. The operational productivity and success of the pilot plant has been proven on a variety of waste feedstock substrates in the form of cow-buffalo manure and potato waste. The plant has an average energy productivity of 384 kWh/day and an annual rate of return was estimated to be 15.4%. The life cycle environmental impact analysis deliberated the significant impact potentials in terms of climate change (kg CO2 equivalent), and fossil depletion (kg of oil equivalent) for three selected substrates: 100% cow-buffalo manure (CBM), 100% potato waste (PW), and a mixture of 75% CBM and 25% PW. The results show the climate change potential of 70 kg, 71 kg, and 149 kg and fossil depletion potential of - 2.43 kg, - 16.45 kg, and 18 kg per 2000 kg of substrate slurry, respectively. As such, the substrate of 100% CBM posed the least climate change impacts whereas 100% PW has been established most effective under the fossil depletion category.

Methanogenesis suppression in microbial fuel cell by aluminium dosing.

Reduction in power production due to loss of substrate to methanogens makes methanogenesis a serious performance limitation in microbial fuel cell (MFC). Aluminium (Al) due to its antibacterial properties easily affects the methanogens, which have a thinner cell membrane and slower growth rate. The effect of Al in suppressing methanogens was thus studied by adding 5 mg/L of aluminium sulphate in anolyte of the treated MFC (MFCT). Reduced COD removal efficiency of 86.11 ±â€¯1.3% was observed in MFCT which was lower than that observed (96.25 ±â€¯1.7%) in the control MFC (MFCC) operated without Al addition. An average volumetric power density of 1.84 ±â€¯0.40 W/m3 was observed in MFCT whereas the average volumetric power density observed in MFCC was 1.54 ±â€¯0.46 W/m3. An internal resistance of 195â€¯Ω was observed in MFCT, which was significantly lower than 349 Ω, as observed in MFCC. The coulombic efficiency (CE) of MFCT was found to be 2.5 times higher than the CE of MFCC. This improved performance of MFCT denoted better biocatalytic activity and electron transfer capability of anodic biofilm of MFCT than MFCC. Higher current generation during electrochemical analysis showed better electron discharge at the anode and lesser electron loss at the interface of electrode and electrolyte.

Design and shelf stability assessment of bacterial agents for simultaneous removal of methane and odors.

Two types of solid bacterial agents for the simultaneous removal of methane and odor were designed using humic soil (De-MO-1) and the mixture of humic soil and tobermolite (De-MO-2) as biocarriers. The bacterial consortium, having the removability of methane and dimethyl sulfide (DMS), was immobilized in the biocarriers, and then stored at room temperature for 375 days without additional treatment. Although the lag period, of which the incubation time required for removing methane and DMS, tended to increase over the storage period, the removability of methane and DMS was maintained during 375 days in both bacterial agents. Key bacteria associated with the removal of methane and odors (Streptomyces, Promicromonospora, Paracoccus, Lysobacter, Sphingopyxis and Methylosystis) could keep their abundance during the storage period. The richness and evenness values of the bacterial communities in De-MO-1 and De-MO-2 ranged 4.89 ∼ 6.50 and 0.89 ∼ 0.98, respectively, indicating that high bacterial diversity was maintained during the storage period. The results suggest that De-MO-1 and De-MO-2, designed for the simultaneous removal of methane and odors, had shelf stabilities over one year.

Evaluation of net protein contribution, methane production, and net returns from beef production as duration of confinement increases in the cow-calf sector1.

Intensification of cow-calf production may provide a sustainable solution for meeting increasing beef demand in the face of diminishing resources. However, intensification with its greater reliance on cereal grains potentially decreases the upcycling of human-inedible protein into beef. A previously described model was used to evaluate cow-calf intensification on beef's ability to meet human protein requirements. Four scenarios were compared, based on a 1,000 cow herd: 1) Conventional cow-calf production system (0CON), 2) cows limit-fed in confinement for 4 mo after weaning (4CON), 3) cows limit-fed in confinement for 8 mo after breeding (8CON), or 4) cows limit-fed in confinement year-round (12CON). Changes were not made to either the stocker or feedlot segments of the beef value chain. Net protein contribution (NPC) was calculated by multiplying the ratio of human-edible protein (HeP) in beef produced to HeP in feed by the protein quality ratio. A NPC >1 indicates that the production system is positively contributing to meeting human requirements, whereas a NPC <1 indicates the sector or value chain is competing with humans for HeP. Methane was estimated based on proportion of forage in diet and total methane production was reported per kg HeP. In the cow-calf sector, HeP conversion efficiency (HePCE) decreased from 2,640.83 to 0.37 while methane production decreased from 4.53 to 1.82 kg/kg HeP produced as the length of intensification increased from 0CON to 12CON. Decreased HePCE resulted in NPC values for cow-calf sector of 8,036.80, 4.93, 2.19, and 1.28 for 0CON, 4CON, 8CON, and 12CON, respectively. Protein quality ratio of the entire beef value chain increased from 3.15 to 3.33, while HePCE decreased from 0.99 to 0.39 as length of intensification increased from 0CON to 12CON. For the beef value chain, NPC was 3.11, 2.30, 1.73, and 1.31 for 0CON, 4CON, 8CON, and 12CON, respectively. Across the value chain, confinement of cows for 12 mo decreased enteric methane from 3.05 to 1.53 kg/kg HeP (0CON and 12CON, respectfully). Additionally, profitability of the cow-calf operation decreased from $249.34 to $102.16 per cow as intensification increased. Of confinement scenarios, probability of loss to an operation was least (4%) for 4CON. Feed costs increased by $260.79 per cow for 0CON when drought conditions existed (0COND). Total methane production was reduced by intensification and none of the scenarios evaluated competed with humans for HeP.

Prevotella copri, a potential indicator for high feed efficiency in western steers.

There has been a great interest to identify a microbial marker that can be used to predict feed efficiency of beef cattle. Such a marker, specifically one that would allow an early identification of animals with high feed efficiency for future breeding efforts, would facilitate increasing the profitability of cattle operations and simultaneously render them more sustainable by reducing their methane footprint. The work presented here suggests that Prevotella copri might be an ideal microbial marker for identifying beef cattle with high feed efficiency early in their life span and in the production cycle. Developing more refined quantification techniques that allow correlation of P. copri to feed efficiency of beef cattle that can be applied by lay people in the field holds great promise to improve the economy of cattle operations while simultaneously reducing their environmental impact by mitigating methane production from enteric fermentation.