Estimation of enteric methane emissions trends (1990–2008) from Manitoba beef cattle using empirical and mechanistic models

Decrease of Greenhouse Gases during an In Vitro Ruminal Digestibility Test of Forage (Festuca arundinacea) Conditioned with Selenium Nanoparticles

The Festuca arundinacea Schreb. is one of the most used forage grasses due to its duration, productivity, great ecological breadth, and adaptability. Livestock has been criticized for its large production of greenhouse gases (GHG) due to forage. The advancement of science has led to an increase in the number of studies based on nanotechnologies; NPs supplementation in animal nutrition has found positive results in the fermentation of organic matter and the production of fatty acids and ruminal microorganisms. The objectives of this study were (1) to evaluate the in vitro digestibility of forage containing selenium (Se) nanoparticles (NPs), and to identify the specific behavior of the ruminal fermentation parameters of F. arundinacea Schreb. and (2) quantify the production of greenhouse gases (total gas and methane) (3) as well as the release of bioactive compounds (phenols, flavonoids, tannins, and selenium) after fermentation. Three treatments of SeNPs were established (0, 1.5, 3.0, and 4.5 ppm). The effects of foliar fertilization with SeNPs son digestion parameters were registered, such as the in vitro digestion of dry matter (IVDM); total gas production (A_{total gas}) and methane production (A_CH4); pH; incubation time(to); the substrate digestion rate (S); t_Smax and the lag phase (L); as well as the production of volatile fatty acids (VFA), total phenols, total flavonoids, and tannins in ruminal fluid. The best results were obtained in the treatment with the foliar application of 4.5 ppm of SeNPs; IVDMD (60.46, 59.2, and 59.42%), lower total gas production (148.37, 135.22, and 141.93 mL g DM^-1), and CH₄ (53.42, 52.65, and 53.73 mL g DM^-1), as well as a higher concentration of total VFA (31.01, 31.26, and 31.24 mmol L^-1). The best results were obtained in the treatment with the foliar application of 4.5 ppm of SeNPs in the three different harvests; concerning IVDMD (60.46, 59.2, and 59.42%), lower total gas production (148.37, 135.22, and 141.93 mL g DM^-1), and CH₄ (53.42, 52.65, and 53.73 mL g DM^-1), as well as a higher concentration of total VFA (31.01, 31.26, and 31.24 mmol L^-1). The F. arundinacea Schreb. plants fertilized with 4.5 ppm released-in the ruminal fluid during in vitro fermentation-the following contents: total phenols (98.77, 99.31, and 99.08 mgEAG/100 mL), flavonoids (34.96, 35.44, and 34.96 mgQE/100 g DM), tannins (27.22, 27.35, and 27.99 mgEC/100g mL), and selenium (0.0811, 0.0814, and 0.0812 ppm).

Quantification of methane emitted by ruminants: A review of methods

The contribution of greenhouse gas (GHG) emissions from ruminant production systems varies between countries and between regions within individual countries. The appropriate quantification of GHG emissions, specifically methane (CH₄), has raised questions about the correct reporting of GHG inventories and, perhaps more importantly, how best to mitigate CH₄ emissions. This review documents existing methods and methodologies to measure and estimate CH₄ emissions from ruminant animals and the manure produced therein over various scales and conditions. Measurements of CH₄ have frequently been conducted in research settings using classical methodologies developed for bioenergetic purposes, such as gas exchange techniques (respiration chambers, headboxes). While very precise, these techniques are limited to research settings as they are expensive, labor-intensive, and applicable only to a few animals. Head-stalls, such as the GreenFeed system, have been used to measure expired CH₄ for individual animals housed alone or in groups in confinement or grazing. This technique requires frequent animal visitation over the diurnal measurement period and an adequate number of collection days. The tracer gas technique can be used to measure CH₄ from individual animals housed outdoors, as there is a need to ensure low background concentrations. Micrometeorological techniques (e.g., open-path lasers) can measure CH₄ emissions over larger areas and many animals, but limitations exist, including the need to measure over more extended periods. Measurement of CH₄ emissions from manure depends on the type of storage, animal housing, CH₄ concentration inside and outside the boundaries of the area of interest, and ventilation rate, which is likely the variable that contributes the greatest to measurement uncertainty. For large-scale areas, aircraft, drones, and satellites have been used in association with the tracer flux method, inverse modeling, imagery, and LiDAR (Light Detection and Ranging), but research is lagging in validating these methods. Bottom-up approaches to estimating CH₄ emissions rely on empirical or mechanistic modeling to quantify the contribution of individual sources (enteric and manure). In contrast, top-down approaches estimate the amount of CH₄ in the atmosphere using spatial and temporal models to account for transportation from an emitter to an observation point. While these two estimation approaches rarely agree, they help identify knowledge gaps and research requirements in practice.

Potential Application of Urease and Nitrification Inhibitors to Mitigate Emissions from the Livestock Sector: A Review

Human activities have caused an increase in greenhouse gas emissions, resulting in climate change that affects many factors of human life including its effect on water and food quality in certain areas with implications for human health. CH₄ and N₂O are known as potent non-CO₂ GHGs. The livestock industry contributes to direct emissions of CH₄ (38.24%) and N₂O (6.70%) through enteric fermentation and manure treatment, as well as indirect N₂O emissions via NH₃ volatilization. NH₃ is also a secondary precursor of particulate matter. Several approaches have been proposed to address this issue, including dietary management, manure treatment, and the possibility of inhibitor usage. Inhibitors, including urease and nitrification inhibitors, are widely used in agricultural fields. The use of urease and nitrification inhibitors is known to be effective in reducing nitrogen loss from agricultural soil in the form of NH₃ and N₂O and can further reduce CH₄ as a side effect. However, the effectiveness of inhibitors in livestock manure systems has not yet been explored. This review discusses the potential of inhibitor usage, specifically of N-(n-butyl) thiophosphoric triamide, dicyandiamide, and 3,4-dimethylpyrazole phosphate, to reduce emissions from livestock manure. This review focuses on the application of inhibitors to manure, as well as the association of these inhibitors with health, toxicity, and economic benefits.

A bibliometric study about energy, environment, and climate change

Using the extended science citation index database (SCI) and social science citation index (SSCI) databases, this paper analyzed the characteristics of publications, research foundations, research hotspots, and the evolutionary tracks of studies in the field of energy, environment, and climate change from 1990 to 2019 using a bibliometric method. This method is useful because it involves the quantitative analysis of large amounts of literature, using mathematical and statistical method. The results showed that the United States (US), the United Kingdom (UK), and China were the countries with the most published papers in the field. The US plays a key role in the cooperation between international institutions. An assessment conducted by the Intergovernmental Panel on Climate Change (IPCC) created the standard scientific reference for the research on climate change and its consequences. From 2006 to 2016, a large number of co-cited papers laid a solid foundation for research in the field. During this period, the research focused on the impact of climate change on the ecological environment, began to propose different countermeasures, and formed a set of mature research methods. From 2017 to 2019, there was an acceleration in the growth rate of the number of published articles. Strategies to address climate change, including renewable energy and energy transition, were the focus during this phase. Future studies are expected to focus on climate change mitigation strategies and energy policies. The findings provide a reference for researchers and can help policy makers balance economic development with environmental protection.

Altering the Gut Microbiome of Cattle: Considerations of Host-Microbiome Interactions for Persistent Microbiome Manipulation

The beef cattle industry represents a significant portion of the USA's agricultural sect, with beef cattle accounting for the most red meat consumed in the USA. Feed represents the largest input cost in the beef industry, accounting for approximately 70% of total input cost. Given that, novel methods need to be employed to optimize feed efficiency in cattle to reduce monetary cost as well as environmental cost associated with livestock industries, such as methane production and nitrogen release into the environment. The rumen microbiome contributes to feed efficiency by breaking down low-quality feedstuffs into energy substrates that can subsequently be utilized by the host animal. Attempts to manipulate the rumen microbiome have been met with mixed success, though persistent changes have not yet been achieved beyond changing diet. Recent technological advances have made analyzing host-wide effects of the rumen microbiome possible, as well as provided finer resolution of those effects. This manuscript reviews contributing factors to the rumen microbiome establishment or re-establishment following rumen microbiome perturbation, as well as host-microbiome interactions that may be responsible for possible host specificity of the rumen microbiome. Understanding and accounting for the variety of factors contributing to rumen microbiome establishment or re-establishment in cattle will ultimately lead to identification of biomarkers of feed efficiency that will result in improved selection criteria, as well as aid to determine methods for persistent microbiome manipulation to optimize production phenotypes.

A typological characterization of Canadian beef cattle farms based on a producer survey

The diverse nature of beef production was captured by establishing a farm typology based on an extensive survey of 1005 Canadian farms in 2011. The survey provided information on the type of operation, cattle numbers, feed storage and management, manure management, land use, producer demographics and attitudes to risk, and technology adoption. Principal component analysis and cluster analysis were used to understand the relationships among variables and to statistically identify farm types. A total of 41 diagnostic variables from 133 survey questions were used to define 16 principal components explaining 68% of the variation. Cluster analysis yielded eight major clusters as distinct farm types. The largest number of farms (37%) was grouped as small-scale, part-time cow–calf operations. Mixed operations (crop–beef) were next most frequent (22%), followed by large cow–calf backgrounding (18%) and diversified cow–calf operations that included crop–beef mixed operations as well as off-farm activities (11%). Cow–calf operations that finished calves comprised 8% of the total farms surveyed. Extensive cow–calf backgrounding operations, large backgrounding/finishing operations, and large finishing operations represented the remaining 3% of the farms. The typology not only provides a strategy by which the Canadian beef cattle industry can be characterized, but also improves understanding of the diversity of farm management practices to help develop policies and beneficial management practices.

Trends in greenhouse gas emissions from dairy cattle in Mexico between 1970 and 2010

The objective of the present work was to estimate and assess trends in greenhouse gas (GHG) emissions, particularly methane (CH4) and nitrous oxide (N2O), from dairy cows in Mexico from the base year of 1970 to 2010. Empirical and mechanistic models were used to estimate enteric methane emissions based on chemical composition of diets. Methane from manure was calculated using Intergovernmental Panel for Climate Change (IPCC) and US Environmental Protection Agency recommended equations. N2O emission was calculated according to IPCC recommendations. Compared with the 1970s, current management practices using modern dairy cows increased feed conversion efficiency 32% and milk yield 62%. GHG emission intensity (i.e. emissions per unit of product) was reduced 30%, 25% and 30% for CH4, N2O and total emissions, respectively. The study showed that although GHG emissions in absolute terms increased in the past 40 years, emission intensity decreased due to higher level of production. This trend is likely to continue in the future, assuming milk production follows the same increasing trend as in other countries in North America.