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Methane Emissions from Cattle
Abstract
Increasing atmospheric concentrations of methane have led scientists to examine its sources of origin. Ruminant livestock can produce 250 to 500 L of methane per day. This level of production results in estimates of the contribution by cattle to global warming that may occur in the next 50 to 100 yr to be a little less than 2%. Many factors influence methane emissions from cattle and include the following: level of feed intake, type of carbohydrate in the diet, feed processing, addition of lipids or ionophores to the diet, and alterations in the ruminal microflora. Manipulation of these factors can reduce methane emissions from cattle. Many techniques exist to quantify methane emissions from individual or groups of animals. Enclosure techniques are precise but require trained animals and may limit animal movement. Isotopic and nonisotopic tracer techniques may also be used effectively. Prediction equations based on fermentation balance or feed characteristics have been used to estimate methane production. These equations are useful, but the assumptions and conditions that must be met for each equation limit their ability to accurately predict methane production. Methane production from groups of animals can be measured by mass balance, micrometeorological, or tracer methods. These techniques can measure methane emissions from animals in either indoor or outdoor enclosures. Use of these techniques and knowledge of the factors that impact methane production can result in the development of mitigation strategies to reduce methane losses by cattle. Implementation of these strategies should result in enhanced animal productivity and decreased contributions by cattle to the atmospheric methane budget.
... Livestock will face enormous challenges in mitigating and adapting to climate change in the coming years, as the growing population's demand for meat and milk is expected to increase [1]. Intensive livestock farming is a significant source of greenhouse gas emissions to the atmosphere, enteric fermentation being one of the primary sources of methane produced [2]. Methane is a potent greenhouse gas, with a global warming potential 34-times stronger than CO 2 [3]. ...
... The emission of enteric CH 4 depends on several factors. Efforts to decrease CH 4 emissions by ruminants focus on diet manipulation, either by increasing the proportion of starch in the diet, including lipids, or using feed additives [2,6,7]. Ionophores are additives traditionally used to improve ruminant productive performance with a concurrent reduction in enteric CH 4 emission [8]. ...
... This could be explained by a negative energy balance, which induces an energy reserve mobilization (from adipose tissue); then, up to 70% of the propionic acid is transported to the liver [29,32,33]. Previously, the addition of CaPr into the diet of finishing lambs has been reported to not alter ADG [2,13,29,34], as in the present study. Likewise, dairy cows infused with propionate directly in the rumen had an increased ADG [35]. ...
The objective of this study was to determine the effects of dietary calcium propionate (CaPr) and monensin (MON) on lamb growth performance, ruminal volatile fatty acids (VFAs), methane (CH4) production, and ruminal bacteria and archaea populations. Forty crossbred ram lambs (initial weight 23.4 ± 2.8 kg) were randomly assigned to one of four diets (n = 10 per treatment): (a) control diet (CONT); (b) MON diet, which contained 30 mg/kg dry matter (DM) of monensin + CONT; (c) CaPr diet, which contained 10 g/kg DM of CaPr + CONT; and (d) MCA diet, which contained both additives (30 mg/kg DM of monensin plus 10 g/kg DM of CaPr) + CONT. Dietary MON or CaPr in lamb diets did not affect (p ≥ 0.05) dry matter intake (DMI), average daily gain (ADG), or DMI/ADG. The main effect (p ≥ 0.05) of CaPr supplementation was observed in acetate concentration and CH4 production. The addition of calcium propionate increased (p < 0.05) Fibrobacter succinogenes, Ruminococcus albus, and Selenomonas ruminantium, whereas CaPr reduced (p < 0.05) methanogenic archaea. The addition of MON and CaPr did not affect lamb performance; however, CaPr improved fermentation kinetics towards more efficient routes, reflected by a reduction in the proportion of methane and methanogenic archaea.
... In the last decades, there has been a substantial effort to measure and mitigate enteric methane CH 4 emissions from ruminants . Enteric CH 4 emissions represent an energy loss by ruminants that ranges between 2 and 12% of the gross energy intake (Johnson and Johnson, 1995), which varies according to animal physiology and behavior, dietary characteristics, and rumen microbial communities (Hristov et al., 2015;Ungerfeld et al., 2022). In addition, CH 4 is a potent greenhouse gas with a global warming potential 28 times greater than CO 2 over a 100-year time frame (Forster et al., 2021). ...
... The literature reports greater enteric CH 4 emissions from ruminants consuming forage-based than grain-based diets (Johnson and Johnson, 1995). Indeed, Gavrilova et al. (2019) report that the emission factor (i.e., energy loss as CH 4 relative to the gross energy intake) varies between 3-4% when ruminants consume diets with more than 85% concentrate in the diet relative to 6.3-7.0% ...
... Ruminants lose about 2 to 12% of gross energy as methane. Additionally, methane is one of the greenhouse gases that are responsible for global warming phenomena and its worldwide negative effects (Johnson andJohnson, 1995 andBelanche et al., 2025). ...
... Ruminants lose about 2 to 12% of gross energy as methane. Additionally, methane is one of the greenhouse gases that are responsible for global warming phenomena and its worldwide negative effects (Johnson andJohnson, 1995 andBelanche et al., 2025). ...
This study aimed to investigate the effect of dried Azolla (Azolla pinnata) graded levels on nutritive value and methane production using the rumen in vitro gas production technique. The experiment consisted of three treatments. The first treatment (T1) was a mix of 30% alfalfa hay and 70% concentrate feed mixture (CFM) as a control. The second (T2) and third treatments (T3) were the same as the control group, but 50% and 100% of soya bean meal (part of CFM) were replaced with dried Azolla for T2 and T3, respectively. The data showed that the inclusion of gradually levels of Azolla in the experimental rations didn't show negative effects on fermentation and nutritive value. Total gas production (GP) after incubation for 24 hours, in vitro dry matter degradation (IVDMD), in vitro organic matter degradation (IVOMD) and neutral detergent fiber degradation (NDFD) had similar values among the tested rations, but without significant differences. On the other hand, graded levels of Azolla resulted in a significant (P<0.05) reduction in metabolizable energy (ME), total digestible nutrients (TDN) and methane production. TDN decreased by 2.63 and 3.50% for T2 and T3 compared to T1, respectively. Methane production was reduced by 31.92 and 47.30% for T2 and T3 compared to T1 respectively. Generally, increasing Azolla levels had no deleterious effects on nutritive value and resulted in a higher reduction in methane production.
... Research is needed to understand goat productivity, especially nutritional interventions, which can impact rumen function and enteric methane emissions (Pragna et al 2018). Feed composition influences CH4 production, which can be reduced by increasing concentrate levels in diets (Beauchemin et al., 2008;Johnson & Johnson, 1995). Sauvant & Giger-Reverdin (2009) found that 35% to 40% grain incorporation in rations can lead to significant improvements in methane emissions, influenced by food intake. ...
... Therefore, the quality of forage affects the activity of rumen microbes and CH4 production in the rumen. Forage species, forage processing, proportion of forage in the diet, and the source of the grain also influence CH4 production in ruminants (Johnson and Johnson 1995). Methane production tends to decrease as the protein content of feed increase and increases as the fiber content of feed increases (Boadi et al. 2004). ...
Smallholder goat production is a vital livelihood strategy for millions of people, particularly women, in developing countries. However, it also contributes significantly to greenhouse gas emissions, particularly methane, which has a global warming potential 28 times higher than carbon dioxide over a 100-year time frame. Climate change is a pressing issue with far-reaching consequences for the environment, human health, and agrarian rural economy. Smallholder goat farmers, particularly women, are among the most vulnerable due to their limited resources, lack of climate information, disparity in access to credit and markets, and dependence on natural resources. This study aims to enhance the resilience of smallholder goat production systems, reduce methane emissions, and improve livelihoods for women smallholder farmers by addressing their specific needs and challenges. A gender-sensitive approach is needed to enhance resilience and reduce methane emissions in smallholder goat production. Women face significant barriers to adopting climate-resilient practices, such as limited access to information and training on climate-resilient practices, and cultural and social barriers. These factors make it difficult for women to invest in these practices, adopt new technologies, and control over resources, which can hinder their ability to adapt to changing environmental conditions. There is a significant research gap on the specific needs and challenges of women smallholder farmers in the context of climate change. This study aims to address this gap by exploring the intersections between gender, climate change, and smallholder goat production, and identifying strategies for enhancing resilience and reducing methane emissions. In conclusion, policies that consider gender in small-scale goat farming are crucial for advancing the rural development, enhancing resilience, and lowering emissions from ruminants. These approaches simultaneously work to narrow the gender gap and promote climate-friendly practices. Key recommendations include supporting women's participation in decision-making, providing access to information for women smallholder farmers to adopt climate-resilient practices, and monitoring and evaluating the impact of climate-resilient practices on resilience and methane emissions in smallholder goat production systems.
... Enteric fermentation (the digestive process in ruminants) is the main source of CH 4 emissions (Zhao et al., 2020). Enteric fermentation not only results in global warming but also loss of energy (Johnson and Johnson, 1995). Various strategies could be utilized to mitigate CH 4 emissions from ruminant animals, including improved management practices, superior genetics, nutritional interventions, and innovative technology (Cottle et al., 2011;Hristov et al., 2013;Kumar et al., 2014;Patra and Yu, 2013;Beauchemin et al., 2022). ...
... One of the most important dietary interventions is the use of feedstuffs with high water-soluble carbohydrates (WSC) and condensed tannins (CT). The WSC and CT in diets can mitigate CH 4 production through a variety of ways, including promoting the production of propionate, which acts as a hydrogen sink, reducing the hydrogen available for methanogens, thus decreasing CH 4 production, altering the rumen microbial community to favor propionate-producing bacteria over CH 4 -producing archaea, shifting fermentation patterns from fiber to more efficient carbohydrate fermentation, which generates less CH 4 (Johnson and Johnson, 1995;Newbold et al., 2005;Patra and Yu, 2013;Ramin and Huntanen, 2013). ...
Enteric fermentation in ruminants produces methane (CH₄), which is a major gas that contributes to global warming. The pods of the carob tree, Ceratonia siliqua L., which are abundant in tannins and water-soluble carbohydrates (WSC), could improve microbial protein yield (MPY) and reduce emissions of CH₄ without influencing digestion. The effects of carob pod supplementation in lamb diets on CH₄ emissions, digestibility, partitioning factor (PF), MPY, and EMPY (efficiency of MPY) were examined in this study. Four iso-caloric and iso-nitrogenous lamb diets (17% crude protein, 2650 kcal/kg dry matter) with differing quantities of carob pods were developed and evaluated using the Menke in vitro gas generation technique. Gas production (GP), CH₄ emissions, digestibility, PF, MPY, and EMPY were evaluated during a 24-hour fermentation using buffered rumen fluid from ‘Awassi’ sheep. The incorporation of carob pods considerably decreased gas and CH₄ production (p < 0.001), with a decrease of up to 15% in CH₄ emission at higher levels of supplementation. The increase in PF, MPY, and EMPY was accompanied by no change in digestibility. At 30% supplementation, MPY increased by 35.32 mg, while EMPY increased to 31.5% from 23.14% in the control. There was a linear reduction in gas and CH₄ emission as the amount of carob supplementation increased. Lamb diets supplemented with 30% carob pods had a 15% decrease in CH₄ emissions and an increase in MPY without any change in digestibility. Additional in vivo research is needed to validate the long-term impacts on performance and health, but the results show promise for carob pods to improve ruminant production and decrease emissions of greenhouse gases.
... Methanogenesis results in a loss of 6-10% of energy consumed by ruminants raised worldwide. Methanogenesis is undesirable from the standpoint of energy efficiency and feed costs [152]. CH 4 emissions from ruminant livestock can be decreased through strategies such as animal management, genetic selection, rumen microbiome manipulation, and nutritional modulation. ...
A review of the current literature on gut microbiota biomarkers reveals a very significant imbalance in research focus. Most studies focus on the taxonomic composition of bacterial microbiota in various clinical conditions, such as obesity, gastrointestinal tract diseases, cardiovascular diseases, and type 2 diabetes (T2DM). In contrast, there are relatively few studies examining methanogenic archaea. This discrepancy may stem from a long-held belief that archaea are not pathogenic microorganisms in humans, coupled with the limited sensitivity of the widely used 16S rRNA method for detecting methanogenic archaea. Several publications highlight the functional differences between predominant hydrogen producers and methane producers. High levels of methane production by microbiota are correlated with obesity, constipation, lower levels of short-chain fatty acids in the intestinal lumen, immune changes, unhealthy aging, and carcinogenesis. Nutritional factors have primarily been investigated to reduce methanogenesis and archaea abundance in livestock, aiming to mitigate ecological issues like global warming. In humans, evidence suggests that certain statins and antibiotics, as well as low FODMAP diets and probiotics, can decrease methane production. Findings from ruminant livestock studies on inhibiting methane production could hold promise for clinical evaluation. We propose that user-friendly, non-invasive, and affordable methods are needed to screen methane-producing individuals. Such methods would facilitate the development of personalized nutritional recommendations and help prevent the onset of various non-communicable diseases.
... Therefore, the result of this study is suggesting that cattle rumen contentare suitable for formulating diet for broiler up to 10% inclusion level without compromising the feed intake and weight gain but could negatively influence these parameters if incorporated beyond 10% in broiler diets.furthermore, the significant decrease observed for feed conversion ratio as the level of cattle rumen content increased in the feed is suggesting that the more the cattle rumen content in the experimental diet the better the diet was utilized. This is in line with the report of Johnson and Johnson (1995), whoargued that the microbial enzymes present in rumen contents can improve the digestibility of fibrous feeds when incorporated into the diets of other livestock species, thus potentially leading to better feed conversion ratios. Furthermore, Riaz and Muller (2019) also recommended in their work that cattle rumen contains numerous microbes responsible for digestion of different feed ingredient especially fibre. ...
... The CH 4 is a byproduct of anaerobic fermentation and represents losses of 2%-12% of the energy consumed by ruminants (Johnson and Johnson 1995), in addition to contributing to global warming. This way, measuring the CH 4 production of a given diet is fundamental for evaluating the sustainability of the production system. ...
This study aimed to evaluate the effects of corn silage intercropped
with Marandu grass with or without pigeon pea on lamb’s ruminal
kinetics and methane (CH4) production. The experimental design
was completely randomised, with two treatments. The in vitro
ruminal kinetics, CH4 production, and fermentation parameters of
ruminal inoculum were evaluated using 12 lambs (four animals
for growing season), in duplicates. Corn silage without pigeon
pea showed higher fraction of dry matter degraded (65.37 vs.
60.69% DMd, respectively) in 24–hour incubation and higher
fraction of organic matter degraded (83.99 vs. 79.12% OMd,
respectively) in 96–hour than silage with pigeon pea. There was
no difference in total gas production, short-chain fatty acids
production, and ammonia–N production of the diets. Linear and
Quadratic models presented higher coefficient of determination,
indicating better fit of these equations to in vitro data during 24–
hour, and Dual–pool Logistic model presented the best results
during 96–hour. Pigeon pea inclusion did not reduce CH4
production, independently of the incubation period (mean 36.94
and 46.91 ml CH4/g DMd, in 24 and 96–hour, respectively). The
study suggests that from a nutritional stance, there were no
benefits in using pigeon pea in lamb’s diets.
... As OC has interesting profile of UFA, the milk and cheese of ruminants fed diets containing OC can be beneficially impacted (ARCO-PÉREZ et al., 2017;NEOFYTOU et al., 2020;VARGAS-BELLO-PÉREZ et al., 2013), resulting in more suitable products to human health. The inclusion of fat sources in ruminant's diets is also recognized as a feasible way to reduce methane emission (JOHNSON & JOHNSON, 1995), the way so that sustainability can be reached in livestock production systems. Ensiling has been proposed as a strategy to allow using OC at animal nutrition, since this by-product deteriorates quickly in the presence of oxygen (HADJIPANAYIOTOU, 1999). ...
Olive cake (OC) is a wet by-product of olive processing that may be used as animal feedstuff. Our objective was to investigate the impact of adding OC on fermentation and aerobic stability of maize and grass silages. Whole-crop maize (326 g dry matter (DM)/kg as fed) and 4 h-wilted elephant grass (229 g DM/kg as fed) were ensiled without (untreated) or with fresh OC (5% as fed basis). Ensiling was performed in experimental silos (n = 3), which remained stored for 99 d. As results, fermentative losses were unaffected by OC (P = 0.17), while the lactic acid concentration decreased (P = 0.02) by 33.7% in silages with OC. The pH of grass silage increased (P < 0.001) by adding OC (4.43 vs. 4.01 in the control), but it did not change the pH in maize silage. The concentration of acetic acid (P = 0.01) decreased by 15.2% in maize silage with OC and increased by 19.4% in grass silage with OC. The ether extract concentration increased (P = 0.02) in maize silage with OC compared to the control, and it was similar between grass silage without and with OC. After feedout, silage aerobic stability was not altered (P ≥ 0.18) by the addition of OC in maize and grass silages. Therefore, a possible fate for OC is to ensile it together maize forage, because there is no impairment of fermentation and aerobic stability of silages. Ensiling OC with grass is not recommended as it worsened the fermentation pattern.
... The agriculture sector contributes 24% of total CH 4 emissions in India, 63% of which comes from the enteric fermentation of livestock [4]. An adult buffalo emits 250-500 L of CH 4 daily via enteric fermentation [5], leading to 2-15% gross energy loss as CH 4 [6]. Therefore, it is essential to use CH 4 mitigation strategies to divert the gross energy loss towards production and to reduce the share of CH 4 in global warming. ...
Purpose
This study evaluates the potential of ramie (Boehmeria nivea L. Gaud) and mango seed kernel (Mangifera indica L.) and their combination in reducing methane emission, modifying rumen fermentation, and influencing ruminal enzymes activity under in-vitro conditions.
Methods
A total mixed ration (TMR) consisting of 40% berseem, 20% wheat straw, and 40% concentrate was used as the control. In the treatment groups, berseem was replaced with ramie at 10%, 20%, 30%, 40%, and 50%. In another trial, mango seed kernel (MSK) was incorporated into the TMR at 1%, 3%, 5%, 7%, and 10% levels. Based on dry matter degradability and methane reduction, the two most effective levels of ramie (40% and 50%) were selected and combined with MSK at different inclusion rates (1%, 3%, 5%, 7%, and 10%) for further evaluation.
Results
The combination of 50% ramie with 5% MSK reduced methane emissions by 36.02% without significantly (P > 0.05) affecting in vitro dry matter and organic matter degradability. Higher levels of MSK significantly (P < 0.05) reduced ammonia nitrogen (NH3-N) concentration and acetic acid production while significantly (P < 0.05) increasing propionic acid levels. However, a significant (P < 0.05) reduction in fiber digestion was observed at higher inclusion levels.
Conclusion
The inclusion of ramie and MSK in the diet effectively mitigates methane emissions while maintaining fermentation efficiency at moderate levels of supplementation (50% ramie + 5% MSK). Further in-vivo research is needed to validate its impact on animal performance and productivity.
Graphical Abstract
... The agricultural sector is a major source of CH 4 emissions, with livestock production contributing 37% of global CH 4 emissions (Sun et al., 2023). Ruminal fermentation in ruminants is livestock's primary source of CH 4 emissions, resulting in a 2%-12% loss of total energy intake (Johnson and Johnson, 1995). Among all anthropogenic CH 4 emissions, ruminant fermentation accounts for approximately 33%, making it the second largest source after fossil fuel activities (Crippa et al., 2021), while CH 4 is 28 times more thermogenic than carbon dioxide (CO 2 ). ...
Introduction
Asparagopsis taxiformis (A. taxiformis) has shown great potential to mitigate methane (CH4) emissions in recent years. This study aims to evaluate the impact of A. taxiformis on methane emissions and to fill the knowledge gap regarding its mechanisms of action in affecting CH4 metabolism and rumen fermentation.
Methods
The experimental design consisted of a control group (CON) and test groups supplemented with 2% (Low), 5% (Mid), and 10% (High) of dried and freeze-dried treatment A. taxiformis, respectively, for 48 h of in vitro rumen fermentation. The optimal combination strategy for mitigating CH4 emissions was confirmed by analyzing nutrient degradation, CH4 production and rumen fermentation parameters, and the mechanism of action was analyzed by metagenomic and metabolomic approaches.
Results and discussion
The results showed that freeze-dried treatment had better potential to mitigate CH4 emissions than dried treatment, and supplementation of freeze-dried treatments at Low, Mid, and High groups significantly reduced CH4 production by 32.44%, 98.53%, and 99.33%, respectively. However, the High group exhibited a huge negative impact on rumen fermentation. Therefore, subsequent analyses focused on the Low and Mid groups to explore the underlying mechanisms. Metagenomics analyses showed that supplementation of freeze-dried treatment with the Mid-level supplementation significantly increased the relative abundance of propionate-producing bacteria such as Prevotella, Ruminobacter, and Succinivibrio, while inhibited acetate-producing bacteria such as Ruminococcus, altered the pattern of volatile fatty acid (VFA) synthesis in the rumen, and reduced H2 availability for methanogenesis and promoted propionate production, indirectly alleviating CH4 production. Moreover, by suppressing the relative abundance of Methanobrevibacter, CH4 production in the rumen was directly suppressed. Furthermore, KEGG pathway analysis showed that A. taxiformis significantly inhibited the abundance of K00399, methyl-coenzyme M reductase alpha subunit, which directly inhibited CH4 synthesis. Metabolomics analysis of A. taxiformis supplementation significantly enriched ketoglutarate, malate, isocitrate, and melatonin, which may have reduced the release of rumen fermented H2, thereby mitigating CH4 emissions. In summary, freeze-dried treatment A. taxiformis at the 5% supplementation level achieved the optimal balance between CH4 mitigation and rumen fermentation efficiency.
... [56] documented similar patterns due to manure storage practices and reduced atmospheric mixing. [57] and [58] observed elevated enteric methane from dairy cattle during winter due to feed composition and housing changes. The universal spring minimum suggests fundamental seasonal constraints on emissions, consistent with [59] but contradicting [14] observations of lagged environmental responses in tropical systems. ...
Methane (CH4) emissions from dairy farming are a significant but under-quantified component of agricultural greenhouse gases. This study provides a satellite-based assessment of dairy-specific methane emissions across Canada using high-resolution Sentinel-5P TROPOMI data. By integrating spatial clustering of 1,701 dairy farms and processors, a quasi-experimental design with paired non-dairy reference regions, and seasonal pattern decomposition, we analyzed national and regional spatiotemporal emission trends. Results show persistently higher methane levels in dairy regions (mean difference: 16.99 ppb), with consistent fall-winter peaks. Notably, the dairy-specific methane anomaly, defined as the concentration difference between dairy and non-dairy regions declined by 62.25% from 2019 to 2024, with a sharp drop during 2022-2023 (-41.11%). Meanwhile, national methane levels rose by 3.83%, with increasing spatial heterogeneity across provinces. An inverse relationship between baseline methane levels and growth rates suggests a convergence effect. Seasonal analysis revealed universal spring minima and fall-winter maxima, offering distinct temporal signatures for source attribution. This study demonstrates the value of satellite-based monitoring for policy-relevant methane assessments and introduces a scalable framework applicable to other regions. The observed narrowing of dairy methane anomaly indicates evolving emission dynamics, potentially reflecting rising baseline methane rather than a definitive reduction in dairy source emissions. This highlights the need for integrated satellite and ground-based approaches to enhance understanding and guide mitigation efforts.
... Increasing pellet feeding leads to less methane production and less acetic acid production. This suggests that reducing enteric methane emissions, which are a major source of greenhouse gases in livestock production, could be good for the environment 37 . ...
The aim of this study was to evaluate the effect of high-quality pellet feed on voluntary feed intake, nutrient digestibility and rumen fermentation in beef cattle. Four beef cattle aged approximately 2–3 years were randomly assigned according to a 4 × 4 Latin square design to compare the replacement of pelleted diets in concentrated diets at 4 levels: 0% of diets (T1), 20% of diets (T2), 40% of diets (T3) and 60% of diets (T4). The results of this study revealed that body weight change rate/day total edible amount, or the amount of feed that can be eaten out of concentrated feed, was not significantly different (P > 0.05) among the beef cattle fed all 4 treatments. The digestibility of dry matter, organic matter, crude protein, NDF and ADF was highest in pelleted-fed beef cattle, at 60%. However, the combination of a pelleted diet and a concentrated diet resulted in a statistically significant reduction in protozoa populations when the pelleted diet level was increased. The level of pelleted feed had no effect on the pH or rumen temperature of the beef cattle. With respect to ammonia nitrogen, the propionic acid, butyric acid and total volatile fatty acid levels increased when the beef cattle were fed more pelleted feed. especially at 60%, but the acetic acid and methane production decreased when the beef cattle were fed higher levels of pelleted feed. Purine derivative release was not significantly different. In addition to purine derivative absorption and microbial nitrogen supply, the efficiency of microbial protein synthesis was greater when beef cattle were fed high-quality pelleted feed than when they were not fed high-quality pelleted feed. The present study concluded that pellet feeding in conjunction with concentrated feed at 60% resulted in decreased methane production, protozoa population and nutrient digestibility, microbial protein synthesis, total volatile fatty acids and propionic acid.
... The methane produced by the enteric fermentation of ruminants is the main anthropogenic source of CH 4 , releasing between 1.6 and 2.7 GtCO2e (Herrero et al. 2016), which reaches about 3.3% of the total anthropogenic GHG (IPCC 2018). On the other hand, ruminal methanogenesis uses up 5%-12% of the gross energy consumed by the ruminant, which is a loss of energy (Johnson and Johnson 1995). Thus, in vitro and in vivo studies are needed to find nutritional alternatives, feedstuffs or additives capable of reducing CH 4 emissions into the environment without compromising the appropriate ruminal fermentation and animal production. ...
Recent studies have shown the anti‐methanogenic capacity of Astragalus mollissimus (AM), a plant found in semiarid environments, which is known to produce 3‐nitro‐1‐propionic acid (3NPA) and 3‐nitropropanol (3NPOH). However, little is known about the effects of direct supplementation in basal diets, given that it is also known to cause cattle poisoning by nitro toxins in rangelands. In the present study, two experiments were carried out to determine CH4 and volatile fatty acid production, animal performance and the presence of nitrocompounds in blood. In Experiment 1, four Pelibuey sheep (BW 52.8 ± 6.05 kg) were assigned to a 4 × 4 Latin square arrangement. In Experiment 2, 20 Dorper sheep were randomized to five treatments. In both experiments, AM was supplemented and fully homogenized into diets consisting of 67% oat hay and 33% concentrate. The supplementation with different amounts of AM reduces (p ≤ 0.05) the total gas and methane production. Methane was reduced by 60% when 1 g AM kg⁻¹ BW day⁻¹ was supplemented. No effects (p > 0.05) were observed in feed consumption and average daily gain. However, feed conversion was increased (p < 0.05) with AM supplementation. Finally, no differences (p > 0.05) were observed in nitrocompound concentration in plasma. These results demonstrate that 3NPA and 3NPOH from biological sources possess desirable anti‐methanogenic properties to be considered supplementation alternatives.
... Recent commitments to reduce greenhouse gas emissions by the global dairy industry (Global Dairy Platform, 2021) and the United States dairy sector (Innovation Center for US Dairy, 2020) require the implementation of scientifically sound on-farm mitigation interventions. Enteric methane (CH 4 ) is a prime target for reduction as it accounts for 44% of global livestock emissions (GLEAM, 2022) and is a loss of metabolizable energy from ruminants (Johnson and Johnson, 1995). Moreover, rapid and drastic reductions in CH 4 could help slow atmospheric warming due to its short-lived nature and high warming potential (Ocko et al., 2021). ...
The objective was to investigate the effects of pulse-dosing the essential oil blend, Agolin Ruminant (EOB), to dairy cows on methane (CH4) production (g/d) and intensity (g/kg milk or energy-corrected milk (ECM)), as well as lactation performance, on a commercial farm. Seventy-two multiparous, mid-lactation cows were blocked by days in milk, parity, and milk yield and housed in a single pen. After a 2-wk covariate period, cows within each block were randomly assigned to one of two treatments for 10 weeks: Control (blank pellets) and EOBP (blank pellets and EOB pellets). The pellets were delivered through double-hopper GreenFeed (GF) units. Hopper 1 of each GF unit contained EOB pellets, formulated to supply ~1 g EOB from the first daily drop of pellets for each EOBP cow. Hopper 2 dispensed blank pellets for the remaining daily drops to EOBP cows and for all drops to Control cows. Enteric gases were measured via the GF units. Milk yields and components were obtained twice weekly, and dry matter intake (DMI) was calculated weekly using milk data, body weight, and body condition score. Overall, cows receiving EOB tended to have lower milk lactose concentration. In week 7, EOBP cows outperformed Control cows in milk yield, ECM, yields of milk protein, lactose, and solids-non-fat, modeled DMI, and CH4 intensity. Inherent limitations of administering EOB through the GF units, as well as a low number of CH4 measurements occurring after peak fermentation, may have contributed to the lack of consistent treatment differences. Our efforts to administer a feed additive to individual cows, and our consideration of how farm management practices influenced the results, contribute to the progress of on-farm CH4 research.
... In the present study, the fat content was found to be 12.89 per cent and the total gas production at 24 hours and methane production were found to be 38 and 4.72 ml respectively. Our present findings might be supported by the above theory and the facts of Johnson and Johnson (1995) who stated that the higher level of fat in Grape pomace may exert its negative effects on gas and methane production through inhibition of the activity of methanogenic archaea, protozoans and biohydrogenation of fatty acid. ...
Background: The use of unconventional feeds is being increased nowadays due to lack of feeds and fodders for livestock especially during scarcity period. Grape pomace, a leftover product from the fruit processing industry waste can be considered as an alternative to conventional feed ingredients. A study was carried out to investigate the potential of Grape pomace as an alternative feed resource for livestock. Methods: Grape pomace samples were collected and analysed for its proximate composition, fibre fractionations, calcium, phosphorus, total tannin, total gas production, in vitro dry matter degradability and methane. Result: The per cent dry matter, crude protein, crude fibre, ether extract, total ash and nitrogen free extract were found to be 79.60, 13.17, 55.28, 12.89, 2.68 and 15.98 respectively. The per cent calcium and phosphorus were 0.50 and 0.31 respectively. Fibre fractions of the per cent NDF, ADF and non-fibrous carbohydrates were 55.24, 52.88 and 16.02 respectively. The in vitro dry matter degradability, organic matter digestibility and metabolizable energy were 19.29, 56.33 per cent and 7.93 MJ/Kg respectively. The short-chain fatty acids and net energy for lactation were calculated to be 8.43 mmol and 4.25 MJ/Kg respectively. The total tannin content was found to be 4.67 per cent. The total methane production by Grape pomace was 12.42 per cent. The results reveal that Grape pomace, valuable fruit industry waste can be used as an alternative feed resource for livestock feeding.
... Anthropogenic activities are major contributors to methane emissions, with agriculture being the primary source. Livestock digestion, particularly in ruminants such as cattle and sheep, produces methane through fermentation, where microbes in the digestive system break down food in the absence of oxygen (Johnson and Johnson, 1995). Additionally, manure management practices, such as storage and spreading, create anaerobic conditions conducive to methane production (Petersen et al., 2013). ...
... Kuhmonen et al. 2024). Livestock production is a significant contributor to environmental impacts (Leip et al. 2015, Herrero et al. 2016, and especially ruminants contribute to methane (CH 4 ) emissions (Johnson andJohnson 1995, Beauchemin et al. 2020). Cattle production also has a significant environmental impact through nutrient surpluses of arable land that potentially result in eutrophication , Hietala et al. 2021). ...
The objective of the study was to model the effects of different milk production intensities on methane (CH4) production and nitrogen (N) excretion of cattle in Finnish milk and beef production when the targeted amount of milk and beef is produced. Beef production strategies at current annual milk production in Finland (2 200 million kg) were optimised by Excel Solver for each combination of milk yield (8 000, 9 000, 10 000, 11 000, and 12 000 kg year-1) and beef production (60, 65, 70, 75, 80, 85, 90, 95, and 100 million kg year-1). Increased milk production intensity decreased total CH4 production at each beef production level. In addition, at the lower levels of beef production than currently (85 million kg) total manure N output decreased with increased intensity of milk production but at current or higher beef production levels the effects of milk yield were small. The current strategy of producing milk and beef with high milk production intensity seems to be effective in terms of CH4 production and N emissions.
... A population of this size will require a 60 % increased agricultural capacity [2] to supply both sufficient caloric energy and nutritious high-quality protein. Current global protein supply is reliant on the livestock industry, where the process of husbandry has low land use efficiency [3] and significant greenhouse gas emissions [4]. To negate these impacts, plant protein sources from chickpea (Cicer arietinum), faba bean (Vicia faba), lentil (Lens culinaris), pea (Pisum sativum) and soybean (Glycine max) are currently utilized and are proposed to partially fulfil the increased protein requirements. ...
Cyano-L-alanine (BCA) and γ-glutamyl-β-cyano-L-alanine (GBCA) are the primary antinutritional compounds present within the seeds of the high protein and drought tolerant orphan legume Vicia sativa . Evidence of neurotoxicity is limited to symptom analysis from animal feed trials whilst the molecular mechanisms underlying suspected neurotoxicity in monogastric animals are largely unknown. In this study, we first optimised an in vitro cell-based assay for rapid testing of BCA and GBCA toxicity in the retinoic acid differentiated SH-SY5Y human neuroblastoma cells. Using this system, we then performed proteomics analyses to determine dysregulated expression of proteins in BCA or GBCA treated of differentiated SH-SY5Y cells. Our findings indicate that BCA affects expression of proteins involved in DNA damage and translation whilst GBCA treatment causes dysregulation of those involved in mitosis and cell cycle. Following BCA treatment, we identified changes in many proteins previously suggested to have close association with neurodegenerative diseases including amyotrophic lateral sclerosis and Alzheimer’s disease as well as cancers. Following GBCA treatment, dysregulation of proteins involved in apoptosis pathways was observed. Finally, the lack of common dysregulated proteins and pathways in BCA or GBCA treated cells indicated that they most likely cause neurotoxicity via distinct mechanisms.
Significance
Antinutritional compounds or toxins limit the use of many potential grain crops including V. sativa (Common Vetch), and BCA and GBCA are the two principal toxic compounds in Common Vetch grain. Vetch grain toxicity is associated with neurotoxic symptoms in animals. Characterizing the proteome of BCA- and GBCA-treated neural cells gives insights into the excitotoxicity mechanism and identification of biomarkers for screening higher quality grain. Quantitative tandem mass tag (TMT) mass spectrometry-based proteome profiling of BCA treated neural cells characterized 6,827 proteins, of which 26 were significantly up-regulated and 73 significantly downregulated. However, TMT proteome analysis of GBCA treated cells identified 76 significantly up regulated and 86 downregulated proteins. These results provide insight into the toxicity of BCA and GBCA and enable future identification of putative direct protein targets. We describe for the first time BCA playing a role in modulating the expression DNA damage proteins and translation, and GBCA playing a role in modulating the expression of mitosis and cell cycle proteins, elucidating the mechanisms of plant-derived toxins in mammalian cell neurotoxicity
Highlights
Established in vitro cell-based toxicity assay for β-cyano-L-alanine and γ-glutamyl-β-cyano-L-alanine.
β-Cyano-L-alanine treatment dysregulated many proteins associated with DNA damage in retinoic acid differentiated SH-SY5Y cells.
γ-Glutamyl-β-cyano-L-alanine treatment dysregulated proteins associated with cell cycle.
... The improvement in feed intake and reduction in methane emission may imply that less feed energy is lost as a result of low methane production which may have made more energy available to the goats to use for weight gains. The results on weight gains in this current study corroborate earlier studies that enteric methane production is a loss of energy that is due to inefficient digestion in the rumen (Johnson and Johnson, 1995), which decrease metabolisable energy intake (MEI) by the animal (McGin et al., 2011;Goel and Makkar, 2012) and may potentially be used for meat production (Eckard et al., 2010). ...
It is suggested that the measurement of methane production from enteric fermentation must be done under situations similar to that of typical farming methods. It is against this background that this study measured methane emission from goats on a farm to ascertain the real situation on most farms. The objective of this study was to measure performance and methane emission from goats fed Ghanaian ruminant diets comprising of basal diets supplemented with browse leaves and to determine the effects of temperature and humidity on methane emission. Ten West African dwarf goats (5 males and 5 females; average weight 14 kg ±1.01) were fed fifteen Ghanaian ruminant diets for four months. Each diet was randomly fed twice in 24 hours for 2 days in a month. Methane emission, temperature and humidity were measured using handheld gas methane detector. Completely randomized design was used. Dry matter intake (DMI) was lowest (P<0.05) when cassava (Manihot esculenta) peels were fed and highest (P<0.05) when plantain peels were supplemented with Moringa oleifera. Weight gain, DMI and methane emission from manure increased with time. The highest enteric methane emission was recorded (P<0.05) when untreated rice straw (749 ppm) was fed and the lowest was recorded (P<0.05) when Moringa oleifera leaves (313 ppm) were fed. High environmental temperature favored low methane emission and high humidity was associated with high methane emission. In conclusion, feeding browse leaves alone and browse supplementation with basal diets resulted in lower methane emission than feeding basal diets alone. Moderate weight gains were recorded. High environmental temperature was inversely related to methane emission and high environmental humidity was directly related to methane emission. It is recommended that, browse leaves be incorporated in the feed of ruminants, especially when environmental temperatures are low and humidity is high.
... Given the non-linearity of the methane production curve, which is known to vary over time and in response to feeding (Hristov et al., 2013;Johnson & Johnson, 1995), Wu (2016) introduced the Cubicle Hood Sampler (CHS) as an innovative approach to monitoring MPR over significantly longer periods of time than other spot sampling methods allow. Placed in the cubicles, this device has the potential of non-intrusively monitoring the MPR from cows for up to 12-h per day, making it very promising. ...
... The main cause of emissions is methane produced during ruminant digestion and feed formulation and processing (FAO 2016). Methane emissions from livestock are influenced by a variety of factors -including the amount of feed consumed, the type of nutritional component in the diet, the type of feed, the diet pattern, the environment, genetic makeup of the animal, host adaptability, changes in ruminal microbiota, and rumen ecology (Johnson and Johnson 1995;Shibata and Terada 2010). That is why various strategies for reducing animal methane output have been demonstrated in years , which improved nutritional management, modifying ruminal fermentation by changing the composition of the feed, adding methane modulators, and defaunation (Shibata and Terada 2010). ...
Methanogenesis is the formation of methane facilitated by a group of organisms from the phylum Archaea. There are three types of methanogenic Archaea depending on the substrate they use as input metabolite. The hydrogenotrophic (use H 2), methylotrophic (use methylated compound), and acetoclastic (utilize acetate) methanogens. These are a biological process where rumen methanogens consume a substrate from fermentation mainly H 2 to obtain energy where CH 4 is the by-product. This enteric methane emission from livestock is both an environmental concern (greenhouse gases) and a production inefficiency as methane output is considered an energy loss. This paper reviews an understanding of methanogenesis and the application of approaches that could maximize production and reduce the release of pollutants under animal agriculture. The type and ratio of carbohydrates could alter the number and presence of microbes due to variations in rumen pH and substrates contained, such structural carbohydrates favor the growth of propionate-forming microbes that affect the rate of methanogenesis. An increase in the propionate ratio indicates a low methane emission as H 2 is redirected away from the creation of methane. Phytochemicals from plants (oil, tannins, saponins) have direct and indirect effects on methanogens, while they also lower the numbers of protozoa that play a significant role in transferring molecular hydrogen, which will be utilized for methanogenesis. Novel rumen modulators like 3-nitrooxypropanol inhibit the methyl coenzyme M reductase (MCR) necessary for methane synthesis and have a remarkable potential to mitigate CH 4. Other strategies include breeding performance, food waste minimization, change in diet preferences, housing and culling, etc. are also ways to decrease methane output. However, there is still a need to validate its effects on animal performance, residues in food, feasibility, availability, and economic grounds.
... There is a need to develop technologies to improve the neutral detergent fiber digestibility (NDFD), which is approximately 55 %, in animals fed a diet based on tropical forage (Cabral et al., 2006). Furthermore, approximately 4 to 14 % of the energy consumed by animals fed with tropical grass is lost in the form of methane (CH 4 ), which is also a greenhouse gas (Johnson and Johnson, 1995), justifying the use of technology that aims to increase NDFD and decrease CH 4 emissions (Nussio et al., 2006). ...
This study aimed to evaluate the effects of supplementation of live yeast (LY) associated with starch levels (SL) on the in vitro kinetic parameters of the gas production (GP), in vitro neutral detergent fiber digestibility (IVNDFD), volatile fatty acid (VFA) and methane (CH4) production of Urochloa brizantha cv. Marandu grass harvested in both the rainy and dry seasons. The study was conducted in a 2 × 3 factorial arrangement, whereby LY supplementation (with and without LY) was associated with 0, 10, and 20 % of starch supplementation. The variables were analyzed using PROC MIXED in SAS (Statistical Analysis System, version 9.3). LY and SL had no interaction effects on any of the variables tested. LY supplementation increased total GP at 72 h of incubation in both forage seasons by approximately 25 %. Additionally, LY supplementation decreased lag time; however, the GP rate was unaffected. The LY also caused a slight drop in IVNDFD at 48 h in both forage seasons. LY supplementation decreased total VFA production by 25.96 % for the rainy season and 11.32 % for the dry season and caused a 40 and 46 % drop in CH4 for the rainy and dry season forage, respectively. The assumption that combining LY and starch would enhance LY activity was not confirmed in this study, as most analyzed variables showed no interaction between the two factors. Consequently, no beneficial effects on increased SL could be attributed to LY supplementation.
Keywords VFA; digestibility; gas production; probiotic
... We hypothesise that although dairy and beef cattle are both same species, the interactions of their distinct diets and digestive physiologies, arising from selection, should be considered. Factors such as the digestive tract volume, mean retention time of digesta, the digestibility of the feed offered, and digestion and fermentation characteristics may affect the accuracy of the Moe and Tyrrell (1979) equation in predicting CH 4 emissions from feedlot cattle (Johnson and Johnson 1995;Hammond et al. 2014). Furthermore, recent research from the Netherlands (van Gastelen et al. 2019) has suggested that developments in management and breeding of ruminant animals in the past few decades may have altered their digestive physiology (i.e. ...
Context
Accurately predicting baseline methane (CH4) emissions from beef cattle is of utmost importance for the beef industry and governments alike. It serves as a vital component for accounting as part of national GHG inventories and enables the development and implementation of greenhouse gas (GHG) mitigation strategies.
Aims
The aim of this study was to evaluate equations in the literature for predicting CH4 emissions of beef cattle when fed barley and wheat-based diets typical of the Australian feedlot industry. Then, propose the best prediction equation to accurately reflect CH4 emissions of feedlot cattle under Australian conditions.
Methods
As part of the project, a large database of methane measurements performed in respiratory calorimeters taken from beef cattle fed a range of feedlot diets was assembled. The dataset included a wide range of factors that are known to impact CH4 production, such as dry matter intake (DMI), ether extract (EE), crude protein (CP), and cell wall components, amongst others. The database contained 713 individual measurements, from 175 animals and 12 studies.
Key results
The equation currently utilised by the Australian National Inventory Report had poor accuracy, with mean bias overprediction of 115 g/day (P < 0.01), along with significant linear bias (P < 0.01) and poor precision (r² = 0.05). The mean bias was 144% of average observed CH4 production. All evaluated equations lacked accuracy and precision in predicting CH4 emissions for the diets fed in this study. Roughage concentrations (DM basis) ranged from 5.54 to 43.0% with a mean of 20.5 ± 11.1%. Given these findings, two specific equations were developed, (1) a CH4 yield equation based on DMI: CH4 (g/day) = 9.89 ± 1.54 × DMI (n = 384; P < 0.01; root mean square error (RMSE) = 32.6 g/day; r² = 0.85); and (2) an equation based on DMI, neutral detergent fibre (NDF) and EE: CH4 (g/day) = 5.11 ± 1.58 × DMI − 4.00 ± 0.821 × EE + 2.26 ± 0.125 × NDF (n = 384; P < 0.05; RMSE = 22.2 g/day; r² = 0.91). When validated, the second equation yielded a mean bias of 6.10 g overprediction, with no linear bias, and better fit than any of the literature equations.
Conclusions
Based on a thorough model evaluation, our findings support the need to revise current methods to predict CH4 for barley and wheat-based diets.
Implications
This study contributes to developing accurate estimations of enteric CH4 emissions for cattle fed barley and wheat-based diets.
... The methane produced during ruminal fermentation represents the primary sink for H₂ in the rumen, which is extremely important for the reoxidation of NADH, thereby ensuring glucose phosphorylation via the glycolytic pathway. However, ruminal methanogenesis results in 2-12% energy losses from the gross energy of the diet and contributes to 5% of greenhouse gas emissions (Johnson and Johnson 1995). ...
The objective of this study was to evaluate the effects of replacing sodium lasalocid (LAS) with different doses of copaiba oleoresin (CO) and dried barbatimão bark (DBB) on the rumen short-chain fatty acid profile in an in vitro ruminal fermentation trial. Two experiments were conducted. In the first, four doses of CO were evaluated (CO-0, 0 µL; CO-0.06, 0.06 µL; CO-0.12, 0.12 µL; and CO 0.18, 0.18 µL of CO), and in the second experiment, four doses of DBB were tested (DBB-0, 0 µg; DBB-130, 130 µg; DBB-200, 200 µg; and DBB-270, 270 µg of DBB). Each experiment was conducted in a randomised block design with a 4×3+1 factorial arrangement, with four doses of natural additive, three levels of concentrate, and one additional treatment (160 µg of LAS). With 500 g/kg concentrate, a positive quadratic effect (P<0.05) on the molar proportion of acetate was observed in response to CO and DBB doses. In both experiments, LAS resulted in a higher molar proportion of propionate (P<0.05). The reduction in the molar proportion of propionate observed in this study suggests that the doses of these additives used are insufficient to replace sodium lasalocid effectively.
... Moreover, it was shown through in vitro experiments that medium-chain fatty acids (8 to 16 C), such as lauric (C12:0) and myristic (C14:0) acids, caused a greater decrease in CH 4 production compared with short (≤8 C) or long (≥18 C) fatty acids [66]. Others suggested that depression in CH 4 production due to lipid supplementation includes a reduction in the amount of organic matter fermented in the rumen [67] and the inhibitory effect of lipids on ruminal microorganisms' activity [68]. ...
This study evaluated enteric methane (CH₄) emissions, dry matter intake (DMI), and performance in rearing beef heifers fed either a Guinea-grass-only diet (0WCS) or Guinea grass supplemented with whole cottonseed (WCS) at 0.5% of body weight (BW). Twenty-four Braford heifers were randomly allocated into four pens (three animals per pen) per treatment over two experimental periods. Methane emissions were measured using the SF₆ tracer technique. Heifers receiving WCS supplementation produced 29% less CH₄ (120.64 vs. 169.54 g/day for 0.5WCS and 0WCS, respectively; p = 0.02) and showed a 22% reduction in CH₄ yield (7.30% vs. 9.41% of gross energy intake; p = 0.02). Methane intensity was 33% lower in supplemented heifers (0.37 vs. 0.55 g CH₄/kg BW; p = 0.01). However, WCS supplementation significantly reduced total DMI and forage DMI (p = 0.01 and p < 0.01, respectively). In terms of performance, heifers in the 0.5WCS group gained 0.28 kg/day, while those in the 0WCS group lost 0.10 kg/day. These results indicate that WCS supplementation mitigates CH₄ emissions while improving weight gain in beef heifers fed low-quality forage diets, making it a promising strategy for enhancing the sustainability of beef cattle production systems.
... Grass silage (CON), typically low in tannins, does not have the same inhibitory effects on rumen microorganisms as tannin-rich diets. Therefore, it often results in higher overall fermentation activity, leading to greater gas and CH 4 production (Johnson and Johnson, 1995). The role of PEG in binding with tannins to mitigate their anti-nutritional effects is well-documented; by complexing with PD, PEG can neutralise the more potent tannin effects, potentially altering fermentation patterns compared to diets without PEG (Lamy et al., 2011). ...
A field trial evaluated the effects of tree species, plant fractions, and season on the dry matter degradability (DMd) and tannin profiles of three tree species (Salix caprea, goat willow (GW); Quercus robur, common oak; Acer campestre., maple). Leaf and twig samples were collected monthly from five trees per species between June and September in Berkshire, UK. Total condensed tannins (CTs) concentrations were determined using a Butanol−HCl assay and tannin profiling (mean degree of polymerization (mDP), and concentrations of procyanidins (PC), prodelphinidins (PD), and cis- and trans- flavan-3-ols) were measured via in situ thiolysis assay. In vitro total DMd was determined using the ANKOM Daisy II system. Data were analysed using linear mixed models with tree species, plant fractions, month, and their interactions as fixed factors, and tree ID (nested within species) as a random factor. Goat willow had the highest (P < 0.05) DMd, total CTs concentrations, mDP, and trans flavan-3-ols. Oak had the highest (P < 0.001) PD concentrations. Maple had the highest final DM, soluble losses, and concentrations of PC, and cis flavan-3-ols. Across all tree species, leaves had a higher (P < 0.001) DMd, soluble losses, and total CTs concentrations, and lower DM (P < 0.001) and mDP (P = 0.043) concentrations than twigs. Soluble losses and DMd increased (P < 0.001) with season, from June to September, while the highest (P = 0.001) DM content was observed in August. Tannin profiles did not vary with seasons, except for the highest (P < 0.001) mDP concentrations in June compared with other months. The impacts of high-PC (96 % in CTs; HPC) and high-PD (73 % in CTs; HPD) GW on total gas and methane (CH4) production were assessed in vitro. Experimental diets were 100 % grass silage (GS, control), HPC (80:20 grass silage:HPC GW), HPD (80:20 grass silage: HPD GW), plus two diets with the addition of polyethylene glycol (PEG) in the HPC and HPD to neutralise tannins. Diets were incubated for 72 h in rumen fluid: medium at 1:9 v/v in triplicate. Gas pressure (psi transducer) and CH4 concentrations (gas chromatography) were measured throughout. Volatile fatty acids (VFA) concentrations and DMd were assessed at 72 h. Data were analysed by linear mixed models using dietary treatment as a fixed factor and batch run (1−3) as a random factor. HPC, HPD, HPC+PEG, and HPD+PEG diets had lower (P < 0.001) DMd and 72 h production of cumulative gas and CH4 than Grass silage (GS). Grass silage produced more (P < 0.001) total VFA and acetic acid concentrations than the four GW diets and less (P < 0.001) butyric acid than HPD. This study concludes that the inclusion of GW reduced in vitro CH4 production, partly due to its tannin content, with PC showing an improved potential. Species and fraction-specific differences in tannin profiles influenced the nutritive value and CH4 mitigation potential of tree fodder, and these need to be accounted for when tree fodder is introduced into animal diets.
... At the animal level, enteric CH 4 emissions (EME) represent an "energy-inefficient" process. An adult cow can lose between 2% and 12% of its gross energy intake, which can vary depending on the nutritional content of the diet consumed (Johnson and Johnson, 1995). Thus, effective and novel strategies to mitigate the environmental and energy-inefficient costs of EME from cattle are required. ...
Environmental pollution and climate change are two of the most pressing challenges humanity and other life forms face. They pose significant threats to health, ecosystems, and the overall sustainability of the planet. Unbelievable, but factually, nine million people die prematurely each year due to air pollution; 80% of wastewater globally is released into the environment without adequate treatment; eight million tons of plastic waste enter the oceans annually; one in four deaths worldwide are linked to environmental pollution. Other eye-openers are that global temperature is projected to rise by 1.5 °C by 2030 and 3.2 °C by 2100; sea levels are expected to rise by 26 cm by 2050 and 82 cm by 2100; climate change could lead to a 10% decline in global gross domestic product (GDP) by 2100; and that 143 million people could be displaced due to climate change by 2050. This chapter outlines a strategic conservation plan aimed at mitigating these risks. This chapter begins by providing a comprehensive overview of the various pollutants and their detrimental effects. It then peeps into the complexities of climate change linked to these and other processes, including its causes, consequences, and future predictions. This chapter’s core focuses on developing a strategic conservation plan. This plan outlines a multipronged approach encompassing (i) Pollution Control and Remediation Strategies, which explores various methods for reducing pollution at its source (prevention) and cleaning up existing contamination (remediation) across different environmental domains (air, water, land). (ii) Climate Change Mitigation and Adaptation Strategies, which addresses strategies for reducing greenhouse gas emissions and mitigating the impacts of climate change, along with adaptation strategies to build resilience in ecosystems and human societies. Beyond the conventional command and control strategies, this chapter emphasizes the importance of public awareness, education, and policy reforms in achieving successful environmental conservation. It highlights the need for international collaboration and a collective global effort toward a sustainable future. Given that pollution and climate change are the major impactors to productivity multifacetedly, this chapter highlights the measures and initiatives toward realizing the UN Sustainable Development Goals.
The dairy sector plays a fundamental role in the economic development of numerous regions by creating jobs and sustaining the livelihoods of millions of people. However, concerns related to animal welfare and environmental sustainability—particularly greenhouse gas (GHG) emissions—persist in intensive dairy systems. This study aimed to measure and assess the presence of GHGs, such as methane (CH4) and carbon dioxide (CO2), in a compost barn facility, using spatial variability tools to analyze the distribution of these gasses at different heights (0.25 m and 1.5 m) relative to the animals’ bedding. Data were collected over five consecutive days using a prototype equipped with low-cost sensors. Geostatistical analysis was performed using R, and spatial distribution maps were generated with Surfer 13®. Results showed elevated CH4 concentrations at 0.25 m, exceeding values typically reported for similar systems values (60–117 ppm), while CO2 concentrations remained within the expected range (970–1480 ppm), suggesting low risk to animals, workers, and the environment. The findings highlight the importance of continuous environmental monitoring to promote sustainability and productivity in confined dairy operations.
With the pressing global challenge of climate change, the potential to breed cattle that produce less lifetime methane offers a transformative solution that is both sustainable and impactful. The objective of this study was to determine the genetic correlations between enteric methane emissions and economically important traits included in the current Terminal Index used to breed animals for meat in Ireland. This Terminal Index is typical of terminal-type indexes used globally, constituting traits associated with calving performance, carcass merit, and efficiency traits such as feed intake and age at finish, as well as some ancillary traits such as docility. Methane and carbon dioxide flux measurements recorded from 2018 to 2024 using ten GreenFeed Emission Monitoring systems in a progeny performance test centre on 1,835 beef animals and a more expansive dataset from commercial farmers with phenotypic performance data on calving performance, carcass quality, and efficiency traits were available on up to 402,039 animals for analyses. Five trait definitions for methane and carbon dioxide emissions were derived: individual spot measures, 1-day, 5-day, and 10-day averages of spot measures, and a full test average per animal, where all emission measurements were averaged across the test period. (Co)variance components between all trait definitions and phenotypic performance traits were estimated using animal linear mixed models. Methane emissions were strongly correlated with feed intake ranging from 0.49 (SE = 0.119) to 0.76 (SE = 0.057) and carcass weight ranging from 0.44 (SE = 0.050) to 0.50 (SE = 0.060) across trait definitions, suggesting that selection for reduced methane emissions could adversely impact growth and performance. An antagonistic correlation was found between methane and age at finish ranging -0.27 (SE = 0.063) to -0.18 (SE =0.084), which suggests that animals who have an earlier finishing age produce more methane per day. Carcass conformation was positively weakly correlated with methane (0.09 to 0.12), thus suggesting there is a potential to select for improved carcass conformation with minimal impact on enteric methane emissions. Overall, these findings emphasize the need for breeding strategies that capture the trade-offs between reducing methane emissions and preserving economically valuable traits such as feed intake, carcass weight, and conformation in beef finishing systems.
This study investigated the feasibility of incorporating Chenopodium album L. (CAL) into ruminant feed ingredients through evaluating the effects of harvest time and substitution levels on in vitro rumen fermentation. In the first phase, a sole-substrate experiment was conducted using CAL harvested from June to August, analyzing its chemical composition and total saponins content. The impact of harvest time on fermentation parameters was assessed with CAL as the sole substrate. The second phase involved a mixed-substrate experiment using an early-fattening Hanwoo diet (30% rice straw and 70% concentrate), where increasing proportions of CAL (control: 0%, T1: 5%, T2: 10%, T3: 15%, and T4: 20%) replaced rice straw. Seasonal variations in CAL composition influenced the fermentation characteristics. CAL harvested in July exhibited higher fermentability, with total volatile fatty acids (TVFAs) reaching 103.87 mM at 72 h. In contrast, CAL harvested in August showed lower fermentability and digestibility. However, August-harvested CAL was selected for the subsequent experiment, as it provided a more practical balance of sufficient biomass yield and a higher saponins concentration, aligned with the study’s methane mitigation objectives, while also exhibiting a fiber composition comparable to that of rice straw. We hypothesized that the saponins in CAL contribute to methane reductions. Supplementation with 15% of CAL significantly reduced methane production per gram of inoculated and digested dry matter (p < 0.05), likely due to differences in crude protein (CP), neutral detergent fiber (NDF), acid detergent fiber (ADF), and saponins content. However, despite having the lowest fiber content, T4 (20% CAL) exhibited the lowest in vitro dry matter digestibility (IVDMD), suggesting that factors such as saponins, CAL’s chemical composition, or microbial shifts may have hindered digestibility. Ammonia–nitrogen production increased from 0 to 3 h, but it continuously decreased between 3 and 9 h due to microbial growth and nitrogen assimilation, as microbes incorporate ammonia into their biomass (p < 0.05). Fermentation characteristics further revealed that the acetate-to-propionate (A/P) ratio decreased with increasing CAL levels, with T4 showing the lowest ratio (1.55 at 72 h), confirming a shift toward propionate-based fermentation. Notably, T2 (10% CAL) showed an optimized fermentation efficiency, producing the highest TVFA concentration at 24 h (98.28 mM). These findings highlight the potential for using CAL as a functional feed ingredient, with moderate substitution levels (10–15%) enhancing fermentation efficiency while reducing methane production.
Reducing the negative environmental impact of production activities without (substantial) loss of production is a crucial challenge for the agricultural sector. Investigating farms' environmental and technical efficiency (TE) levels and drivers can contribute to addressing this issue. In this regard, based on recent theoretical developments on the appropriate handling of undesirable outputs in the modeling of production technologies, this paper introduces a multi‐equation stochastic frontier framework for technical and environmental efficiency (EE) analysis. This framework is applied to a sample of French suckler sheep farms. The results indicate that, on average, farms in the sample can increase their desirable output by 20% without using more inputs while reducing their greenhouse gas emissions by 24%. Findings also show that relatively high (low) levels of TE are associated with relatively low (high) levels of EE and that the likelihood for a farm to be both technically and environmentally efficient is relatively low. Only 32% of the farms in the sample have a high level of TE and EE. Drivers such as decoupled direct payments are positively associated with EE and negatively associated with TE, while no significant effect is found for green direct payments.
Buku ini disusun secara lengkap dengan tujuan
untuk memudahkan para pembaca memahami isi buku ini. Buku
ini membahas tentang Pengenalan Nutrisi Ruminansia, Anatomi
dan Fisiologi Sistem Pencernaan Ruminansia, Proses Fermentasi
Mikroba Rumen, Komponen Nutrisi Ruminansia, Kualitas Pakan
untuk Ruminansia, Pengolahan Pakan Ruminansia, Evaluasi
Nutrisi Pakan Ruminansia, Manajemen Kesehatan Ruminansia
Melalui Nutrisi, Metabolisme Nutrisi, Strategi Pemberian pakan
Ruminansia.
Enteric methane emissions (EMEs) negatively impact both the environment and livestock efficiency. Given the proposed link between CH4 yield and the rumination time (RT) phenotype, we hypothesize that this connection is mediated by the gut microbiome. This study investigated the RT-microbiome-EME connection using rumination-bolus, fecal, and rumen microbiomes as non-invasive proxies for identifying low-EME cows. High-RT cows ruminated 94 minutes longer per day (20%) and exhibited 26% lower EME than low-RT cows, confirming a strong RT-CH4-yield association. Microbial analysis revealed conserved methanogen diversity across the rumen, bolus, and fecal microbiomes, though functional differences were evident. High-RT cows had a greater abundance of Methanosphaera stadtmanae, suggesting an increased potential for methylotrophic methanogenesis, whereas low-RT cows exhibited higher Methanobrevibacter YE315 abundance, indicative of CO2-utilizing methanogenesis. Additionally, high-RT cows showed increased alternative hydrogen sinks, supported by upregulated genes encoding fumarate reductase, sulfate reductase, nitrate reductase, and ammonia-forming nitrite reductase, thereby reducing hydrogen availability for methanogenesis. Metabolically, high-RT cows had higher propionate concentrations and were enriched with rapid-fermenting bacteria (Prevotella, Sharpea, Veillonellaceae, and Succinivibrionaceae), whereas low-RT cows exhibited higher acetate concentrations with elevated acetate-producing pathways, reflecting differences in energy partitioning mechanisms. This study establishes RT as a microbiome-linked, non-invasive screening tool for identifying low-EME cows. The observed microbial and metabolic shifts in high-RT cows suggest that RT-based selection could enhance methane mitigation, rumen efficiency, and climate-smart livestock production. Leveraging RT-associated microbial profiles offers a scalable and cost-effective approach to reducing EME in cattle.
IMPORTANCE
Methane emissions from livestock contribute to climate change and reduce animal efficiency. This study reveals that cows with longer rumination times (chewing cud for an extra 94 minutes daily) produce 26% less methane than cows with shorter rumination times. The gut microbiome plays a key role—low-methane cows host microbial communities that produce less methane while efficiently utilizing hydrogen for energy conservation in the rumen. By analyzing rumination sensor data and/or in combination with microbial profiles from rumen or fecal samples, farmers can non-invasively identify and select cows that naturally emit less methane. This scalable, cost-effective strategy offers a practical solution for reducing livestock’s environmental footprint while enhancing efficiency and advancing climate-smart agriculture.
Ruminal methanogenesis represents considerable energy loss within the fermentative processes mediated by microbial populations, by means of which up to 12% of gross energy intake is driven away from microbial protein synthesis (MPS). This review explores the relationship between methane (CH4) synthesis and emission with MPS in beef cattle, focusing on the nutritional, biochemical, and microbial factors modulating these processes. The synthesis of CH4 by ruminal archaea is essential for maintaining redox balance during the fermentation of carbohydrates. This process diverts metabolic H2 from energy-efficient pathways like propionate synthesis, which could otherwise enhance microbial growth. Dietary factors, including carbohydrate fermentability, N synchronization, and passage rate, modulate MPS. Diets based on roughage might enhance CH4 synthesis while impairing MPS efficiency by reducing diet digestibility and promoting microbial shifts towards methanogenic populations. Potential mitigation strategies, including plant secondary metabolites, CH4 inhibitors, and controlled forage-to-concentrate ratios, demonstrate the potential to reduce CH4 emissions while enhancing nutrient utilization. This review underscores the need for integrated approaches combining dietary strategies, advanced feed additives, and improved prediction models to optimize ruminal fermentation, enhance MPS, and reduce the environmental footprint of beef cattle systems.
In low- and middle-income countries (LMIC), particularly in South Asia and sub-Saharan Africa, livestock production is dominated by smallholder production systems characterized by low productivity and high greenhouse gas (GHG) emissions intensity coupled with high vulnerability to climate change-related natural disasters. Yet, these countries lead the world in the future demand for livestock products. For instance, the projected growth in protein demand for red meat between 2020 and 2050 is greatest in south Asia (49%) and sub-Saharan Africa (55%) relative to global estimates (14%). Most LMIC aim to meet the increasing demand for meat and milk by increasing livestock numbers, which perpetuates the high GHG emissions intensity in these countries. Rather, emphasis should be on increasing productivity per animal through increased adoption of climate-smart interventions that sustainably increase productivity, efficiency and resilience. Such interventions must go beyond the current focus on reducing enteric methane emissions from intensive livestock production systems to include interventions that also improve adaptation to climate change, and that are appropriate for extensive smallholder livestock systems. Thus, additional factors such as affordability and socio-cultural appropriateness are particularly important determinants of adoption. We recommend the use of a systems lens to examine existing GHG mitigation strategies in terms of their efficacy as well as their support for adaptation to climate change, socio-cultural acceptability, and promotion of livestock’s contribution to food and nutritional security and livelihoods. Policy changes necessary to foster adoption of such climate-smart livestock production interventions in LMIC are discussed.
The aim of this systematic review and meta-analysis was to evaluate the relationship between RFI (residual feed intake) and traits related to methane emissions in cattle. Searches were performed in PubMed and Web of Science using keywords in English. The selected studies compared traits related to methane emissions between animals with divergent RFI and/or the correlation between traits related to methane emissions and RFI. Meta-analysis was performed for traits showing three or more uncorrelated results. After application of the exclusion and inclusion criteria, 27 studies were included in the present review. Meta-analysis of the comparison of means was possible for seven traits and meta-analysis of phenotypic correlations for three traits. CH4 emission (g/day) was significantly lower in negative RFI animals and was positively correlated with RFI, indicating that animals with lower dry matter intake without affecting production traits (low RFI) emit less CH4 into the environment. However, the results for the other traits evaluated were inconclusive due to insufficient data for meta-analysis. Meta-analyses clearly demonstrated that cattle with lower RFI emit less enteric methane. The primary reason why more efficient animals emit less enteric methane appears to be the reduced availability of substrate for fermentation. Therefore, genetic selection of cattle for feed efficiency, beyond reducing feed costs within the production system, plays a critical role in promoting environmentally sustainable production.
Aquaculture contributes to economic growth, employment and food security. In the existence of climate change, climate-smart production systems are required. This chapter proposed the use of solar energy, integrated aquaculture-agriculture (IAA), recirculating aquaculture systems (RAS), aquaponics and biofloc as solutions for the impact of climate change to aquaculture. Solar energy provides power to enhance aeration, maintaining temperatures and waste removal. IAA is an aquaculture farming system performed concurrently with other agricultural activities. Recirculating aquaculture systems, aquaponics and biofloc use small amount of water and land. To evaluate the effectiveness of the solutions for climate change impacts, circular economy concept, life cycle assessment and artificial intelligence are described. Circular economy, life cycle assessment and artificial intelligence consider environmental sustainability. This chapter describes solutions and evaluation mechanisms that are expected to enhance adaptations and mitigation options.
1) This study aimed to investigate the effects of various washing pre-treatments of native Codium fragile as a feed additive on in vitro ruminal fermentation and CH 4 production in ruminants. Seaweed was included at 0.5% dry matter (DM) based on the experimental feed (forage : concentrate = 3:7). Treatment groups were classified as follows: experimental feed (C), no washing (T1), washing at 0°C (T2), washing at 22°C (T3) and washing at 70°C (T4) each immersed for 6 minutes in distilled water. The pH consistently fell within the ruminal stability range. In vitro dry matter digestibility was significantly highest in T2, T3, T4 and C, T4 was the lowest at 48 h (p<0.05). NH 3-N concentration was significantly highest in T4 at 48 h (p<0.05). Total gas production at 48 h was 19% lower in T4 compared to C (p<0.01). CH 4 production (mL/g DM) at 48 h was lower in all treatment groups compared to C, with T3 showing a 31% reduction (p<0.01). Similarly, CH 4 production (mL/g dry matter degradability, DMD) at 48 h was 39% lower for T3 compared to C (p<0.01). At 24 h, total VFA was significantly highest in T1 and T4 (p<0.05). The proportions of acetate was significantly highest in C and T3 was the lowest at 48 h (p<0.01). The proportions of propionate was significantly highest in T3 and C was the lowest at 48 h (p<0.01). The acetate to propionate ratio was singnificantly highest in C at 48 h (p<0.01). The proportions of butyrate at 24 h was lower for T3 compared to C (p<0.05). Therefore, this study confirms that Codium fragile can reduce CH 4 production when used as a feed additive for ruminants and this effect is not significantly influenced by the washing pre-treatment. However, if washing process is necessary, washing at 22°C is the most appropriate method to remove foreign objects. (
Context The effects of garlic (Allium sativum L) intervention on ruminant productivity have been studied with inconsistent results, thus making it hard to utilize this data in decision-support systems in the ruminant industry. Aim This meta-analysis assessed the effectiveness of garlic in improving dry matter intake (DMI), rumen fermentability, nutrient digestibility, blood biochemical indices, and reducing methane emissions in small ruminants. Methods Nineteen (19) articles were identified via systematic searches performed in PubMed, Web of Science, Google Scholar, and Scopus databases. The Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines were used for the analysis. Data was pooled using the random-effects model, and results were expressed as mean differences (MD) at a 95% confidence interval. Subgroup analyses were conducted to explore the impact of small ruminant types (sheep versus goats) on response variables. Mixed-effect meta-regression analysis was performed to quantify the impact of moderators [breeds, body weight (BW) at the beginning of the study, duration of garlic intervention, sex, diet types, small ruminant types, and dosage] on the observed heterogeneity on volatile fatty acid (VFA). Heterogeneity and publication bias were assessed using standard methods. Key results The pooled result indicates that garlic increased the concentrations of ruminal VFA (P = 0.039), acetate (P < 0.001), and propionate (P < 0.001), and decreased methane emissions (P < 0.001). The results show that garlic increased the digestibility of dry matter (DM) (P = 0.008), ether extract (EE) (P = 0.001), crude fiber (CF) (P < 0.001), and neutral detergent fiber (NDF) (P = 0.002). Pooled estimates also revealed that garlic decreased concentrations of blood cholesterol (P = 0.004) and low-density lipoprotein (LDL) (P < 0.001). Subgroup analysis showed that small ruminant types influenced the results of the meta-analysis. Meta-regression showed that small ruminant types, breeds, diet types, and BW were the drivers of inconsistent results in small ruminants on garlic intervention. Egger’s regression asymmetry test showed the absence of publication bias, indicating that the results were valid and reliable. Conclusion This meta-analysis highlights the potential of garlic intervention in small ruminants to enhance the digestibility of DM, EE, CF, and NDF, increase the levels of ruminal VFA, acetate, and propionate, and decrease blood cholesterol, LDL, and ruminal methane emissions. Implications The current study sets guidelines for standardized experimental designs on the use of garlic in ruminant nutrition in the future.
Certain assumptions are made which permit the calculation of the amounts of CO2 and CH4 produced in the rumen which correspond to a given molar distribution of volatile fatty acids present in rumen fluid. This calculation allows the development of a theoretical fermentation balance for a given molar distribution of volatile fatty acids. For a molar distribution of 65 acetate: 20 propionate: 15 butyrate, the following balance is calculated:
57.5(C6H12O6)→65 acetate+20 propionate+15 butyrate+60 CO2+35 CH4+25 H2O
The assumptions upon which the calculations are based are discussed, such as considering volatile fatty acids, CO2 and CH4, as sole fermentation products and using the empirical formula C6H12O6 to represent fermentation substrate. An attempt is made to evaluate the fermentation balance in terms of known experimental data which bear on product-substrate relationships. Values predicted from the theoretical equation are of the same order of magnitude as experimental values.
Application of the balance is made to amplify the interpretation of experimental data concerned with variations in the molar distribution of fatty acids on various dietary regimes. It is proposed that the fermentation balance is useful for interpreting certain quantitative aspects of ruminant nutrition in terms of the quantitative aspects of the rumen microbial fermentation.
A system for the rapid determination of O2 consumption, CO2 production and subsequent indirect estimation of energy metabolism of ruminants has been updated and validated. The accurate determination of gas temperature, relative humidity, absolute pressure and flow is important to the overall use of the system. Analogue outputs from the specific analyzers were multiplexed and then routed to a data acquisition system with appropriate software control. Subsequent data processing included modification to fit LOTUS 1-2-3 files. The analyzers were calibrated with standard test gases for the gas meters. In an experimental confirmation trial, eight sheep were fed at maintenance (M) or 2× maintenance (2M) or fasted 48 h after each level of intake (MF and 2MF, respectively) and subsequent energy metabolism was determined. Oxygen consumption (mL min−1), metabolic rate (W) and CO2 production (mL min−1) were greater (P < 0.05) for animals fed 2M (111.2, 379.5 and 101.9, respectively) than for those fed M (85.4, 291.2 ...
In October 1987, NSF, NASA, and NOAA jointly sponsored a workshop at Columbia University to assess the experimental tools and analysis procedures in use and under development to measure and understand gas and particle fluxes across this critical air-surface boundary. This report presents the results of that workshop. It is published to summarize the present understanding of the various measurement techniques that are available, identify promising new technological developments for improved measurements, and stimulate thinking about this important measurement challenge.
Four ruminally cannulated Hereford steers (531 +/- 32 kg) without weights (control; C) or with 24-kg weights (W) in the rumen were used in a double crossover design experiment to determine the effects of changes in frequency of reticular contractions at maintenance feed intakes on passage rates of particulate matter and fluid from the rumen. Duration of reticular contractions, apparent digestibilities and heat and methane productions were also determined. Weights in the rumen had no effect (P = .07) on frequency of reticular contractions before feeding; however, frequencies of reticular contractions were higher in C than in W steers during feeding (P = .03) and after feeding (P = .05). Weights in the rumen increased the average duration of contractions before feeding (P = .04), during feeding (P = .01) and after feeding (P = .05) by 12, 15 and 15%, respectively. Fractional outflow rates of ruminal and whole gastrointestinal particulate matter were 38% and 49% lower (P = .001) in C than in W steers, respectively. Weights in the rumen reduced (P = .001) methane production (liters/d) by 29%. Methane production was inversely correlated with fractional outflow rate for ruminal particulate matter (r = -.53; P = .034). Heat productions for W and C steers were 12.3 and 12.6 Mcal/d, respectively. Weights in the rumen had no effect on apparent digestibility. Duration of reticular contractions, in contrast to frequency of contractions, was the important factor influencing passage rates of both ruminal fluid and particulate matter. Methane production was decreased when passage rates were increased.(ABSTRACT TRUNCATED AT 250 WORDS)
Fecal suspensions from humans were incubated with 13CO2 and H2. The suspensions were from subjects who harbored 10(8) and 10(10) methanogens per g (dry weight) of feces, respectively, and from a subject who did not harbor methanogens. Quantitative nuclear magnetic resonance spectroscopy showed that acetate labeled in both the methyl and carboxyl groups was formed by suspensions from the subject without methanogens and the subject with the lower concentrations of methanogens. The amounts of labeled acetate formed were in agreement with the amounts expected based on measurements of H2 utilization. No labeled acetate was formed by suspensions from the subject with the higher concentrations of methanogens, and essentially all of the H2 used was accounted for by CH4 production. Suspensions from the subject with lower concentrations of methanogens produced both methane and acetate from H2 and CO2. The results indicate that reduction of CO2 to acetate may be a major pathway for microbial production of acetate in the human colon except when very high concentrations of methanogens (ca. 10(10) per g [dry weight] of feces) are present. Double-labeled acetate was also formed from H2 and 13CO2 by fecal suspensions from nonmethanogenic and moderately methanogenic rats.
Eight bull calves (four Holsteins and four Ayrshire calves with mean birth weight of 38.8 kg) were ruminally cannulated at 3 d of age and allocated to one of two weaning programs. All calves were fed colostrum for 3 d after birth and milk until weaning. Calves in the conventional-weaning program were fed a starter diet from 3 d of age and weaned at 6 wk of age. In the early-weaning program, calves were fed a highly palatable pre-starter diet from 3 d of age until they consumed 227 g/d, and then fed a mixture of pre-starter (227 g) and starter diet ad libitum. Calves in this group were weaned at 4 wk of age. Ruminal samples were collected at 3 and 7 d, then weekly thereafter through 8 wk and at 10 and 12 wk of age to assess microbial activity. Calves in the early-weaned group had a higher concentration of total ruminal volatile fatty acids at an earlier age than the calves in the conventional-weaning program. This was accompanied by a trend toward higher lactate concentrations and lower ruminal pH in the early-weaned group during their first 4 wk of age. Lactate and ammonia concentrations decreased with calf age. The total anaerobic bacterial counts increased slightly with calf age, whereas Streptococcus bovis and facultative bacterial populations decreased with calf age. Amylolytic, proteolytic, lactobacilli, lactate-utilizers, cellulolytic and methanogenic bacterial populations increased progressively in both groups. Cellulolytic and methanogenic bacteria were present in both groups at 3 d of age. No protozoa were detected in calves of either group. In general, the most significant changes in bacterial populations and metabolic activity in both groups occurred between 4 and 6 wk of age. Although calves in both groups had similar patterns of bacterial development, calves in the early-weaning program tended to have high ruminal microbial activity at an earlier age than the conventionally weaned calves.
Six 300-kg steers were each fed a 70% cracked corn plus corn silage diet at two levels of intake above maintenance with and without 3 mg monensin/kg.75 body weight (W.75). A changeover design was used. Dietary energy and nitrogen were partitioned by duplicate, 22-h indirect respiration calorimetry measurements of heat and methane production on each animal concurrent with 7-d total feces and urine collection trials. Feed and feces were analyzed for energy, N, starch and neutral detergent fiber (NDF). The partial efficiency and(or) heat increment of metabolizable energy (ME) used for gain and maintenance was partitioned by regression of energy storage vs intake. At equalized gross energy intakes (adjustments made by covariance), monensin improved (P less than .01) the apparent digestibilities of energy, from 71.8 to 74.8%; NDF, from 50.5 to 57.5%, and crude protein, from 61.6 to 65.8%. Methane production averaged 5.7% of the control gross energy (GE), but was reduced by 26% (P less than .01) by monensin additions. Metabolizable energy was increased (P less than .01) from 63.3 to 66.8% of gross energy intake by monensin, resulting in an increase (P less than .01) in retained energy (64.7 to 72.3 kcal/W.75). Heat production was increased (P less than .05) by monensin, but only in proportion to the increased ME. Daily energy retentions adjusted to equal ME intake were similar with or without monensin (69.9 vs 67.1 kcal/W.75). No significant effects of monensin on the heat increment of ME use for maintenance or gain were observed. Both NEm and NEg were improved by approximately 7% by monensin; however, the relative effect on NEm vs NEg depends on method of calculation. At equalized GE intakes, approximately one-third of the improved energy utilization was explained by the reduced methanogenesis caused by monensin and two-thirds by reduced fecal losses.
Syntrophococcus sucromutans is the predominant species capable of O demethylation of methoxylated lignin monoaromatic derivatives in the rumen. The enzymatic characterization of this acetogen indicated that it uses the acetyl coenzyme A (Wood) pathway. Cell extracts possess all the enzymes of the tetrahydrofolate pathway, as well as carbon monoxide dehydrogenase, at levels similar to those of other acetogens using this pathway. However, formate dehydrogenase could not be detected in cell extracts, whether formate or a methoxyaromatic was used as electron acceptor for growth of the cells on cellobiose. Labeled bicarbonate, formate, [1-C] pyruvate, and chemically synthesized O-[methyl-C]vanillate were used to further investigate the catabolism of one-carbon (C(1)) compounds by using washed-cell preparations. The results were consistent with little or no contribution of formate dehydrogenase and pointed out some unique features. Conversion of formate to CO(2) was detected, but labeled formate predominantly labeled the methyl group of acetate. Labeled CO(2) readily exchanged with the carboxyl group of pyruvate but not with formate, and both labeled CO(2) and pyruvate predominantly labeled the carboxyl group of acetate. No CO(2) was formed from O demethylation of vanillate, and the acetate produced was position labeled in the methyl group. The fermentation pattern and specific activities of products indicated a complete synthesis of acetate from pyruvate and the methoxyl group of vanillate.
Two energy balance experiments each used 6 high-yielding dairy cows. In the first, a 3 X 3 Latin square with one replicate, rations were of 7 kg hay and 11 to 14 kg of concentrates having crude protein 251 g and gross energy 17.9 MJ/kg, given alone or with 5% tallow or 5% soya bean oil. Three weeks of adaptation were followed by 10 to 12 days when excreta were collected and gas exchange estimated. Digestibility and metabolizable energy of concentrates and hay were also assessed using wethers fed to maintenance only. Intakes of DM and digestibility of nutrients other than lipid did not differ among treatments with either sheep or cows. There were no apparent differences in rumen fermentation in the one cannulated cow used, and energy loss in urine was also unaffected. Lipid supplement reduced methane loss. Milk yield and milk energy were increased with tallow, with a simultaneous reduction of milk fat and percentage of protein. Soya bean oil reduced the percentage of milk fat and milk energy produced. The second trial, using similar animals and with similar management had a change-over design in which the concentrate was given alone or with 7% tallow. Results confirmed those of trial 1. The effect of level of feeding on the efficiency of utilization of energy is discussed. (Abstract retrieved from CAB Abstracts by CABI’s permission)
6頭の山羊を用いて,エネルギー代謝とルーメン液および血液性状に及ぼすプロトゾアの影響を調べた.飼料は,実験1では乾草のみ,実験2では乾草+濃厚飼料,実験3では実験2の飼料にモネンシンを添加したものとした.プロトゾア存在の山羊は不在のものに比べ,いずれの実験でもルーメン液中のアンモニア濃度と酪酸の比率が高かったが,プロピオン酸の比率は低かった.モネンシンはプロトゾア数を減少させプロピオン酸の比率を上昇させた.エネルギー代謝については,実験1ではプロトゾアの影響は認められなかったが,実験2ではプロトゾアの存在によるメタン生成量の増加が認められた.いずれの実験でも,プロトゾアの存在によりエネルギーの尿への損失は高まり,糞への損失は低下し,蓄積量は高まる傾向がみられた.飼料Nの消化率も同様に上昇したが,尿中N損失がプロトゾアの存在で高まったため,N蓄積量にはその有無で差は認められなかった.モネンシンはエネルギーのメタンと糞への損失を低下させ尿中N損失を増加させた.血漿グルコース濃度は実験2と3ではプロトゾア存在の方が高く推移したが,尿素-N濃度には差は認められなかった.モネンシンによりこれらの濃度は高まる傾向がみられた.
Schemes for estimating methane production in the rumen and in the whole animal from isotope dilution data are promulgated and a unifying mathematical analysis of these schemes is presented. In addition to steady-state conditions (appropriate under constant- or frequent-feeding regimes) and isotope administration by constant infusion, significant attention is given to non-steady state conditions and to isotope administration by single injection. A calculation for estimating volatile fatty acid production from methanogenesis is also presented.
A respiratory pattern analyzer for livestock is described. Continuous measurements can be made of oxygen consumption and respiratory output of carbon dioxide, methane and carbon-14, from which rates of heat production can be estimated by indirect calorimetry. The apparatus was designed on the basis of four modules (respiratory gas collection; gas flow and monitoring; gas sampling and analyses; recording) which can be operated independently or as integrated systems. The module components are duplicated in different forms to permit flexibility and ease of operation in studies on livestock subject to various thermal environments and experimental situations.
The relationship among diet composi- tion, intake, and methane production was investigated with data during 404 total energy balance trials with Holstein cows. Methane production in all trials was measured in open circuit respiration chambers. The most useful predictor of total methane production was amounts of soluble residue, hemicellulose, and cellu- lose that apparently were digested. The regression was methane (Meal) = .439 + .273 + .015 kg digestible soluble residue + .512 -+ .078 kg digestible hemicellulose + 1.393 + .097 kg digestible cellulose.
SUMMARY An apparatus for the continuous culture of rumen microorganisms is described, which has a dual effluent removal system designed to simu- late the differential flows for liquids and solids found in the rumen. In this apparatus a portion of the fermentation media is removed through a filter (primarily fluid), while mixed fluid and solid media flow out an overflow port. This per- mits a rapid buffer input rate for maintenance of pH levels, while allowing a longer residence time for digestion of solid particles. The main- tenance of protozoa numbers in this system was found to be improved compared to reported numbers in single overflow systems operated at dilution rates greater than one. Feed rates, buf- fer flow rates, protozoa numbers and other fer- mentation parameters are reported. In addition, a feeding system for continuous culture studies is described which permits frequent, variable feeding of solid feeds.
The purpose of this paper is to describe a method for determining methane emission factors for cattle. The technique involves the direct measurement of methane emissions from livestock in their natural environment. A small permeation tube containing SF[sub 6] is placed in the cow's rumen, and SF[sub 6] and CH[sub 4] concentrations are measured near the mouth and nostrils of the cow. The SF[sub 6] release provides a way to account for the dilution of gases near the animal's mouth. The CH[sub 4] emission rate can be calculated from the known SF[sub 6] emission rate and the measured SF[sub 6] and CH[sub 4] concentrations. The tracer method described provides an easy means for acquiring a large methane emissions data base from domestic livestock. The low cost and simplicity should make it possible to monitor a large number of animals in countries throughout the world. An expanded data base of this type helps to reduce uncertainty in the ruminant contribution to the global methane budget. 18 refs., 3 figs., 3 tabs.
Methane has been measured in air samples collected at approximately weekly intervals at 23 globally distributed sites in the NOAA/GMCC cooperative flask sampling network. Sites range in latitude from 90 S to 76 N, and at most of these we report 2 years of data beginning in early 1983. All measurements have been made by gas chromatography with a flame ionization detector at the NOAA/GMCC laboratory in Boulder, Colorado. All air samples have been referenced to a single secondary standard of methane-in-air, ensuring a high degree of internal consistency in the data. The precision of measurements is estimated from replicate determinations on each sample as 0.2%. The latitudinal distribution of methane and the seasonal variation of this distribution in the marine boundary layer has been defined in great detail, including a remarkable uniformity in background levels of methane in the Southern Hemisphere. We report for the first time the observation of a complete seasonal cycle of methane at the South Pole. A significant vertical gradient is observed between a sea level and a high altitude site in Hawaii. Globally averaged background concentrations in the marine boundary layer have been calculated for the 2 year-period May 1983–April 1985 inclusive, from which we find an average increase of 12.8 ppb per year, or 0.78% per year when referenced to the globally averaged concentration (1625 ppb) at the mid-point of this period. We present evidence that there has been a slowing down in the methane growth rate.
Sulfur hexafluoride tracer was used in a series of experiments to simulate isoprene emissions from an isolated oak grove. The measured tracer release rate and ambient concentrations of isoprene and SF6 observed along downwind sample lines were combined to determine the mass flux of isoprene from the forest. The fluxes determined from the tracer data increased exponentially with temperature and were in close agreement with estimates determined from emission rates measured in a series of branch enclosure samples. The results of this field study demonstrate the feasibility and usefulness of simulating forest emissions as a tool for investigating turbulent transport in forested areas. Isoprene emission fluxes that can be applied in regional models are reported.
Thesis (Ph. D.)--Colorado State University, 1995. Includes bibliographical references.
Thesis (Ph. D.)--Colorado State University, 1994. Includes bibliographical references.
Typescript (photocopy). Thesis (Ph. D.)--Colorado State University, 1978. Includes bibliographical references (leaves [92]-100).
Typescript (photocopy). Thesis (Ph. D.)--Colorado State University, 1989. Includes bibliographical references (leaves [57]-62).
1. The paper describes the development and construction of an apparatus for maintaining a normal microbial population of the rumen under strictly controlled conditions over long periods of time.
2. The apparatus is simple to construct and operate. It is possible to do four replicate experiments at the same time.
3. The results of three experiments are given. The experiments showed that when the steady-state was reached it could be maintained indefinitely, with the type and quantities of products of fermentation very similar to those in the rumen of donor animals, including the maintenance of normal protozoal populations for up to 49 d.
4. It was found that within wide ranges, the digestibility of rations and the output of products were independent of dilution rate.
5. Except for the lowest ‘level of feeding’, the digestibility was independent of the level of feeding. The output of products was proportional to the amount of food digested and was the same as would be expected in sheep on similar rations.
6. An experiment in which a ration of hay was changed to a mainly concentrate ration showed that the fermentation characteristics were determined mainly by the food given.
1. An isotope tracer method for estimating methane production in sheep is described.
2. The technique was used to estimate methane produced in both the upper and lower digestive tract and to determine the routes by which it was excreted.
3. Four Merino ewes given lucerne chaff (33 g every hour) were used.
4. Total methane production rate was 21±1.1 ( se ) ml/min; production in the rumen accounted for 87±1.2% of the total production; 95±1.4% of the methane produced in the rumen was excreted by eructation.
5. Of the methane produced in the lower digestive tract, 89±2.3% was excreted through the lungs and 11% through the anus.
Data from six experiments (two with dry cows) were used to predict partitioning of gross energy to CH4 in Holstein cows using selected independent variables, some of which were intercorrelated, and a stepwise backward elimination regression procedure. Methane outputs ranged from 3.1 to 8.3% (mean 5.5) of gross energy intake for 134 dry cow balance trials and from 1.7 to 14.9% (mean 5.2) of gross energy intake for 358 lactating cow energy balance trials. This is equivalent to 176 and 300 g/d or 245 and 419 L/d of CH4 for dry and lactating Holstein cows, respectively. Digestibilites of hemicellulose and neutral detergent solubles were positive predictors, and cellulose digestibility was a negative predictor of CH4 output in dry cows fed all forage diets, but hemicellulose digestibility was not a significant variable for predicting CH4 production by lactating cows fed diets with concentrate and forages. Fiber digestibility generally remained in models to predict CH4 output. Except for one data set, regression equations accounted for 50 to 72% of the variation in percentage of gross energy partitioned to CH4 by Holstein cows. Results confirm that increased concentrate feeding reduces CH4 production. Supplementation of lactation diets with fat generally increases fat digestibility, and this trait was associated with reduced CH4 output. Results enable 1) estimation of CH4 output for calculation of metabolizable energy and 2) computation of the contribution from dairy cows to global warming.
The intestinal tract of invertebrate and vertebrate animals, including man, is an anoxic habitat wherein microbial formation of acetate from H2 + CO2 is often a major H2-consuming reaction. This paper will discuss the magnitude and microbiology of H2/CO2 acetogenesis in animal guts, its impact on host animal nutrition, competition for H2 between anaerobic microbes, and the global significance of intestinal H2/CO2 acetogenesis.
Five strains of acetogenic bacteria were isolated by selective enrichment from the rumen of a mature Hereford crossbred steer fed a typical high forage diet. Suspensions of rumen bacteria, prepared from contents collected 7 h postfeeding, blended and strained through cheesecloth, were incubated in a minimal medium containing 10% clarified rumen fluid under either H2:CO2 (80:20) or N2:CO2 (80:20) headspace atmosphere. The selection criterion was an increment of acetate in the enrichments incubated under H2:CO2. Periodically, the enrichment broths were plated onto agar media and presumed acetogenic bacteria subsequently were screened for acetate production. Selected acetogenic bacteria utilized a pressurized atmosphere of H2:CO2 to form acetate in quantities 2 to 8-fold higher than when grown under N2:CO2. All presumptive acetogenic isolates were derived from either the 10(-7) or 10(-8) dilutions of rumen contents. All 5 strains were Gram-positive rods, and all utilized formate, glucose and CO. One strain required, and all were stimulated by, rumen fluid. No spores were observed with phase-contrast microscopy and two strains were motile. No methane was detected in the headspace of pure cultures grown under either gas phase. The isolation of these bacteria indicates that acetogenic bacteria are inhabitants of the rumen of the bovine fed a typical diet and suggests that they may be participants in the utilization of hydrogen in the rumen ecosystem. Strain 139B (= ATCC 43876) is named Acetitomaculum ruminis gen. nov., sp. nov. and is the type strain of this new species.
An open-circuit indirect respiration calorimetry system for the collection of long-term metabolic heat production data for medium and small animals is described. The system is designed for use with small ruminants, but it has the capacity for measuring heat production in nonruminant species up to 150 kg. The system consists of an internal climatic control system, air flow control and volume measuring system, and gas analyzers for O2, CO2 and CH4. Carbon dioxide recovery checks of the four chambers produced recovery values ranging from 96.73 to 100.89%. The actual mean fasting heat production measured for 12 wether sheep was 63.13 kcal/kg.75 +/- .83. The total estimated cost of four chambers and the associated instrumentation was less than $17,000 in 1984.
An in vitro continuous culture system to simulate processes in the rumen is described. This comprises a culture vessel (Fig. 2) fed continuously with pelleted solid feed (Fig. 1); artificial saliva also enters the vessel while effluent leaves it continuously in two streams, one is filtered and the other simply overflows (Fig. 1). In this way liquid and solid turnover times may be manipulated independently; in a trial experiment the former and latter were 6.3% and 3.4% per hour respectively. In four replicated experiments a steady-state was achieved in 5-6 days with a feed of barley, tapioca, fishmeal, urea and straw and maintained for a further 7 to 14 days. During a steady-state period, rumen characteristics in terms of protozoal count, pH, redox potential, total volatile fatty acid concentration and ammonia concentration were stable and similar to those found in the rumens of animals given similar diets. Flows of microbial N compounds were assessed by infused Na2H32PO4 with the artificial saliva and estimating the 32P label incorporated in bacterial fractions. The system demonstrably provided a satisfactory means for studying many aspects of rumen function.
Nine steers (300 to 350 kg body weight) were divided into three groups and received either no ionophore, monensin or lasalocid in a 70% cracked corn basal diet for the entire experiment. Within each group, a 3 X 3 Latin-square design was used to evaluate the effect of a high cation concentration added to the diets on in vivo methanogenesis. The three cation treatments consisted of NaCl or KCl addition (Na or K increased to 2.5% of diet dry matter) or no cation addition. Sodium addition decreased methane production in the monensin group 19% when compared with control (P less than .05). Sodium also tended to decrease methane in the lasalocid group (P less than .1) but had no effect on the no-ionophore group. There was no significant effect of K addition on methane production when compared to no added cation. However, K tended to increase methane in both the lasalocid and no-ionophore groups and decrease methane in the monensin group. Results of this experiment support in vitro evidence that cation levels may modulate ionophore effects on methane production.
Eight steers (327 kg average) were fed diets containing either nontreated or anhydrous NH3-treated wheat straw in a two-period crossover design. Intake and digestibilities of dry matter, gross energy, neutral detergent fiber, acid detergent fiber and crude protein were measured by total collection. Energy losses in urine and methane were determined. Heat production was determined by indirect respiration calorimetry on steers fed both diets and after they were fasted. Ammoniation of the straw raised its N content from .49 to 1.59% (P less than .001). Dry matter (DM) intake was increased (P less than .01) by the process from 1.0 to 1.3% of body weight. Digestibility coefficients of dry matter and energy, as well as those for fiber, were increased (P less than .001) by four percentage units or more. Crude protein digestibility, however, was depressed (P less than .001) from 67.8% to 53.5% by ammoniation. Urinary energy as a percentage of gross energy intake (GEI) was reduced (P less than .05) by NH3 treatment from 4.10 to 3.74%. Methane energy was not different (P greater than .10). Metabolizable energy was improved (P less than .001) by ammoniation, increasing from 45.2 to 50.0% of GEI. Daily heat production was higher (P less than .01) for steers consuming the ammoniated straw diet, increasing from 113.7 to 125.3 kcal/wt.75), and was due to higher metabolizable energy intake (MEI) since partial efficiency of MEI used for maintenance did not differ (P greater than .10) between diets. The higher net energy value of the ammoniated wheat straw diet (1.45 vs 1.26 kcal/g DM) was due mainly to decreased fecal loss and a slight decline in urinary loss.
1. Nine experiments, each with one of six sheep with cannulated rumens given a constant diet of dried grass, were made in which oleic, linoleic or linolenic acid was infused into the rumen and energy and lipid metabolism were measured. One experiment was made in which palmitic acid was given. 2. Judged by changes in the composition of isolated fatty acids, the unsaturated fatty acids were hydrogenated in the rumen. An increase in the excretion of lipid in the faeces occurred when the unsaturated acids were given. The heat of combustion of the faeces increased by 12.6±3.0 kcal/100 kcal fatty acid, of which 94% was accounted for by the additional lipid. 3. Methane production fell when the unsaturated fatty acids were infused, the decreases being 13.8±1.6 kcal CH4;/I00 kcal oleic acid, 14.2±1.5 kcal CH4/100 kcal linoIeic acid and 16.4±1.3 kcal CH4/100 kcal Iinolenic acid. The introduction of a double bond into an n-alkyl acid was calculated to reduce methane production by 0.24±0.09 moles/mole double bond. 4. Because the depression of methane production on infusing the fatty acids exceeded the increase in the heat of combustion of the faeces, the metabolizable energy of the fatty acids was 104.1±5.3% of their heat of combustion. 5. The efficiencies with which the fatty acids were used to promote energy retention were 74.6±5.7% for oleic acid, 79.2±2.0 % for linoleic acid and 82.5±3.0% for linolenic acid. These efficiencies agreed with those noted in experiments by others with rats, horses and pigs given glycerides, but were higher than those noted by others when glycerides were added to the diets of ruminants.
1. Twelve steers fitted with rumen cannulas were used in three separate experiments to investigate the effects of the presence or absence of rumen ciliate protozoa on methane production. The diet consisted of 850 g barley and 150 g protein supplement/kg, and was given in three feeds daily at a restricted level of 61 g/kg live weight 0.75 . Animals were defaunated initially by allowing ad lib . consumption of this diet and were then maintained ciliate-free by isolation or were faunated by inoculation with a mixed ciliate suspension. Samples of rumen fluid were taken routinely for the assessment of microbial populations and for volatile fatty acid (VFA) analysis and energy and nitrogen balances and digestibility measurements were made at intervals while animals were confined in respiration chambers.
2. In each experiment the rumen VFA proportions changed from a high-propionate pattern under ciliate-free conditions to a low-propionate, high-butyrate pattern in the presence of ciliates: differences between treatments were highly significant (P < 0.001). There were also marked differences between treatments in CH, production but a reliable comparison was possible only in Expt 3, in which CH 4 was significantly higher (P < 0.001) in the presence of a rumen ciliate population. In Expt 3 the increased loss of energy as CH 4 in the faunated animals amounted to 44 MJ/100 MJ energy intake.
3. Stoichiometric estimates of CH 4 production derived from the observed VFA proportions showed good agreement with CH 4 production as measured in respiration chambers. On average, the stoichiometric CH 4 values overestimated CH 4 production by a factor of 1.08.
4. Highly significant linear relationships (P < 0.001) were observed between the molar proportion of each major VFA and the quantity of CH 4 produced: the proportion of propionic acid was inversely related to CH 4 and showed the lowest residual standard deviation of all the relationships examined.
5. The losses of energy in faeces and urine did not differ between treatments hence the increased loss of energy as CH 4 in the faunated animals resulted in a significant reduction in the metabolizability of the diet from 0.73 to 0.69 (P < 0.05). No significant differences were detected between treatments in heat production, apparent digestibility coefficients or N balance.
6. It is suggested that the rumen ciliates, by modifying the rumen VFA proportions, are directly responsible for the increased CH 4 production in faunated animals.
1. The frequency of association between methanogenic bacteria and ovine rumen ciliates was studied in the rumen fluid of a fistulated sheep.
2. A period of fasting and flushing of the rumen content with nitrogen resulted in a relatively high association, whereas the intake of food and flushing with hydrogen caused a detachment of the methanogenic bacteria from the ciliates.
3. The changes in the frequency of association can be correlated with the relative attribution to the H 2 production by hydrogenogenic bacteria and rumen ciliates.
Between 1979 and 1992 we took some 120,000 measurements of atmospheric methane at Cape Meares on the Oregon coast. The site is representative of methane concentrations in the northern latitudes (from 30 deg N to 90 deg N). The average concentration during the experiment was 1698 parts per billion by volume (ppbv). Methane concentration increased by 190 ppbv (or 11.9 percent) during the 13-year span of the experiment. The rate of increase was about 20 +/- 4 ppbv/yr in the first 2 yr and 10 +/- 2 ppbv/yr in the last 2 yr of the experiment, suggesting a substantial decline in the trend at northern middle and high latitudes. Prominent seasonal cycles were observed. During the year, the concentration stays more or less constant until May and then starts falling, reaching lowest levels in July and August, then rises rapidly to nearly maximum concentrations in October. Interannual variations with small amplitudes of 2-3 ppbv occur with periods of 1.4 and 6.5 yr.
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