Mitigate Methane Production Research Articles

Methane Reduction Potential of Two Pacific Coast Macroalgae During in vitro Ruminant Fermentation

With increasing interest in feed-based methane mitigation strategies and regional legal directives aimed at methane production from the agricultural sector, identifying local sources of biological feed additives will be critical for rendering these strategies affordable. In a recent study, the red alga Asparagopsis taxiformis harvested offshore Australia was identified as highly effective for reducing methane production from enteric fermentation. Due to potential difference in methane-reduction potential and the financial burden associated with transporting the harvested seaweed over long distances, we examined locally sourced red seaweed A. taxiformis and brown seaweed Zonaria farlowii for their ability to mitigate methane production when added to feed widely used in the Californian dairy industry. At a dose rate of 5% dry matter (DM), California-sourced A. taxiformis and Z. farlowii reduced methane production by up to 74% (p ≤ 0.05) and 11% (p ≤ 0.05) during in vitro rumen fermentation respectively. No effect on CO2 production was observed for either seaweed. The measured decrease in methane production induced by A. taxiformis and Z. farlowii amendment, suggest that these local macroalgae are indeed promising candidates for biotic methane mitigation strategies in California, the largest milk producing state in the US. To determine their real potential as methane mitigating feed supplements in the dairy industry, their effect in vivo will need to be investigated.

Comparative Microbiome Analysis Reveals the Ecological Relationships Between Rumen Methanogens, Acetogens, and Their Hosts.

Ruminant methane, which is generated by methanogens through the consumption of hydrogen and supports the normal function of the rumen ecosystem, is a major source of greenhouse gases. Reductive acetogenesis by acetogens is a possible alternative sink that can dispose of hydrogen for acetate production. However, the distribution of rumen methanogens and acetogens along with the relationships among methanogens, acetogens, and their host are poorly understood. Therefore, we investigated the rumen methanogen and acetogen communities of 97 individual animals representing 14 ruminant species within three ruminant families Cervidae (deer), Bovidae (bovid), and Moschidae (musk deer). The results showed that the Methanobrevibacter spp. and acetogens associated with Eubacteriaceae were the most widespread methanogens and acetogens, respectively. However, other methanogens and acetogens exhibited host specificity in the rumen of reindeer and Chinese muntjac deer. Acetogen and methanogen communities were not correlated in these species, and the phylosymbiosis signature between host phylogeny and the composition of both communities was lacking. The abundance of Methanobrevibacter gottschalkii was negatively correlated with the degree of papillation of the rumen wall. Finally, co-occurrence analysis showed that the variation of the predicted methane yields was characterized by the interactive patterns between methanogens, acetogens, and concentrations of rumen metabolites. Our results show that rumen methanogen and acetogen communities have low compositional interdependence and do not exhibit parallel host evolution, which suggests that the strategies for mitigating methane production should be based on a species-specific rumen microbiota analysis.

Mitigation of Rumen Methane Emissions with Foliage and Pods of Tropical Trees.

Simple SummaryMethane produced by enteric fermentation contributes to the emission of greenhouse gases (GHG) into the atmosphere. Methane is one of the GHG arising from anthropogenic activities with the greater contribution to global warming. This paper provides a brief introduction to the potential use of tropical foliage trees, pods, and secondary metabolites to reduce methane emissions from ruminant supply chains. A better knowledge of the available strategies for efficient foliage use in the tropics is essential in order to ensure increasing livestock production while preserving the environment. The mitigation of rumen methane production through the use of the foliage and metabolites of tropical trees represents an interesting challenge for scientists working in the field of ruminant nutrition.Methane produced by enteric fermentation contributes to the emission of greenhouse gases (GHG) into the atmosphere. Methane is one of the GHG resulting from anthropogenic activities with the greater global warming contribution. Ruminant production systems contribute between 18% and 33% of methane emissions. Due to this, there has been growing interest in finding feed alternatives which may help to mitigate methane production in the rumen. The presence of a vast range of secondary metabolites in tropical trees (coumarins, phenols, tannins, and saponins, among others) may be a valuable alternative to manipulate rumen fermentation and partially defaunate the rumen, and thus reduce enteric methane production. Recent reports suggest that it is possible to decrease methane emissions in sheep by up to 27% by feeding them saponins from the tea leaves of Camellia sinensis; partial defaunation (54%) of the rumen has been achieved using saponins from Sapindus saponaria. The aim of this review was to collect, analyze, and interpret scientific information on the potential of tropical trees and their secondary metabolites to mitigate methane emissions from ruminants.

The effect of total and individual alfalfa saponins on rumen methane production.

Ten varieties of alfalfa (Medicago sativa L.) were evaluated for saponin content. Two of the most promising varieties were chosen so that their effect on rumen fermentation and methane production could be studied. Initially, four Hohenheim gas tests (HGT) were performed to test the effect of increased levels of total saponin extracted from the two alfalfa cultivars (Kometa and Verko) - either as fresh material or ensiled - on the total bacteria, total protozoa, methane emission, and selected methanogenic population. Afterwards, seven particular saponins were extracted from fresh alfalfa of the Kometa variety and tested in 24 h batch fermentation culture experiments. The ensiled forms of both the Verko and Kometa alfalfa varieties seem to be good sources of saponin, capable of reducing methane production (P < 0.05) without negatively affecting the basic fermentation parameters. Of the two evaluated varieties, Kometa was the most effective, and the saponins extracted from its roots 3-Glc,28-Glc Ma, medicagenic saponin, and 3-Glu Ma showed the most evident effect (P = 0.0001). The most promising aerial alfalfa saponin in mitigating methane production was soysaponin I K salt (P = 0.0001). Three mixtures of saponins were tested and all were found to mitigate methane production; however, one mixture (MIX 1) did so only to a very small extent. Saponins have been observed to have differing effects depending on their source; however, the mode of action of saponins depends on their direct or probable indirect effect on the microorganisms involved in methane production. © 2019 Society of Chemical Industry.

Influence of Corymbia citriodora leaf extract on growth performance, ruminal fermentation, nutrient digestibility, plasma antioxidant activity and faecal bacteria in young calves

The effect of Corymbia citriodora leaf extract on growth performance, nutrient digestibilities, rumen fermentation, and health status of male crossbred Holstein calves was evaluated in the present study. Three treatments were evaluated by mixing C. citriodora leaf extract (CC) at 0 (CC0), 10 (CC10) or 20 (CC20) ml in the milk of the Holstein calves for 15 weeks. By GC/MS analysis, the main compounds identified in C. citriodora leaf aqueous extract were methyl(Z)-9-oleate (12.69 %), oleic acid (12.13 %), 2-methylene-5α-cholestan-3β-ol (11.18 %), and methyl 12,15-octadecadiynoate (7.73 %). A significant decrease was noticed in intakes of milk, calf starter, hay, and total dry matter (DM) in the calves supplemented with leaf extract at 20 ml. The supplementation of leaf extract at 10 ml/calf did not affect the final body weights, average daily gain, and feed conversion ratio, whereas the extract showed a quadratic decrease (P < 0.001) in the body weight gains and feed conversion ratio at 20 ml/calf. Digestibility of DM, crude protein, neutral detergent fiber, and acid detergent fiber decreased quadratically (P < 0.001) with supplementation of C. citriodora leaf extract in milk. The rumen pH and total volatile fatty acid concentration were similar among the treatments, while the molar proportions of volatile fatty acids differed with a decrease in acetate and butyrate and an increase in propionate concentrations in leaf extract supplemented diets. Further, ruminal NH3-N concentration showed a quadratic decrease with increasing levels of leaf extract supplementation. Feeding C. citriodora leaf extract resulted in lower dry matter and neutral detergent fiber degradation, acetate to propionate ratio, protozoan population, and methane production compared to control. Apart from increasing the plasma antioxidant enzymatic activities, the leaf extract supplementation, irrespective of the dosage, showed a marked reduction in faecal pathogenic bacterial counts, indicating an improved health status. The C. citriodora leaf extract could be supplemented at 10 ml/calf/day to improve the health status and manipulate rumen fermentation in mitigating methane production without any negative effects on the growth performance of calves.

Evaluation of a rumen modifier in buffaloes to mitigate methane production

Evaluation of a rumen modifier in buffaloes to mitigate methane production

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

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

Rambutan fruit peel powder and dietary protein level influencing on fermentation characteristics, nutrient digestibility, ruminal microorganisms and gas production using in vitro fermentation techniques.

The objective of this study was to evaluate the effect of rambutan (Nephelium lappaceum) fruit peel powder (RP) on fermentation characteristics, rumen microorganisms, and in vitro gas production. Three levels of crude protein (CP) in the concentrate (14%, 16%, and 18% CP) and supplementation of rambutan peel powder (0, 2, 4, and 6% of the total dietary substrate) were designed for treatments according to 3 × 4 factorial arrangement in a completely randomized design (CRD). The rumen fluid samples were collected from two-fistulated dairy bulls which had been fed on rice straw with concentrate to adjust the rumen environment. The ratio of roughage (R) and concentrate (C) at 60:40 was used, and all ingredients were added according to the mentioned ratio, respectively. Under this study, supplementation of CP at different levels in the concentrate diet significantly altered (P < 0.05) rumen NH3-N at 6 and after 12h of incubation, whereas the rumen pH was not significantly changed with CP and RP supplementation levels at any times of incubation. The rumen pH was declined at 18% CP at 6h of incubation time, as compared to 14 and 16% CP with 0% RP supplementation. The CP and RP supplementation could enhance and maintain the rumen pH during incubation to the optimum condition. The RP supplementation significantly doubled bacterial population while reduced protozoal population; however, fungal zoospores were not altered with CP and RP supplementation. The ruminal propionate (C3) production was remarkably higher (P < 0.05) by the RP and CP supplementation. The ratio of acetate to propionate (C2:C3) was decreased (P < 0.05) with RP supplementation. Meanwhile, rumen methane (CH4) production was significantly reduced by the RP supplementation. In addition, high level of RP supplementation (6% of total substrate) also significantly decreased the cumulative gas production and the in vitro true digestibility (%IVTDMD). Level of CP had no effect on rumen fermentation while interactive effects of CP level and RP supplementation were not found. This current study indicated that RP supplementation could suppress protozoal population, mitigate methane production, and improve rumen fermentation.

Reducing methane production with corn oil and calcium sulfate: Responses on whole-animal energy and nitrogen balance in dairy cattle

The addition of fat and calcium sulfate to diets fed to ruminants has resulted in a reduction in methane production, but the effects on energy balance have not been studied. A study using indirect calorimetry and 16 multiparous (8 Holstein and 8 Jersey; 78 ± 15 d in milk; mean ± standard deviation) lactating dairy cows was conducted to determine how mitigating methane production by adding corn oil or calcium sulfate to diets containing reduced-fat distillers grains affects energy and nitrogen balance. A replicated 4 × 4 Latin square design with 35-d periods (28 d of adaption and 4 d of collections) was used to compare 4 different dietary treatments. Treatments were composed of a control (CON) diet, which did not contain reduced-fat distillers grain and solubles (DDGS), and treatment diets containing 20% (dry matter basis) DDGS (DG), 20% DDGS with 1.38% (dry matter basis) added corn oil (CO), and 20% DDGS with 0.93% (dry matter basis) added calcium sulfate (CaS). Compared with CON, dry matter intake was not affected by treatment, averaging 29.6 ± 0.67 kg/d. Milk production was increased for diets containing DDGS compared with CON (26.3 vs. 27.8 ± 0.47 kg/d for CON vs. DDGS, respectively), likely supported by increased energy intake. Compared with CON, energy-corrected milk was greater in DG and CO (30.1 vs. 31.4, 31.7, and 31.0 ± 0.67 kg/d for CON, DG, CO, and CaS, respectively). Compared with CON, the addition of calcium sulfate and corn oil to diets containing DDGS reduced methane production per kg of dry matter intake (22.3, 19.9, and 19.6 ± 0.75 L/kg per d for CON, CO, and CaS, respectively). Similarly, methane production per kilogram of energy-corrected milk was reduced with the addition of calcium sulfate and corn oil to diets containing DDGS (14.2, 12.5, and 12.4 ± 0.50 L/kg per d for CON, CO, and CaS, respectively). Compared with CON and CaS, the intake of digestible energy was greater for DG and CO treatments (57.7, 62.1, 62.0, and 59.0 ± 1.38 Mcal/d for CON, DG, CO, and CaS, respectively). Intake of metabolizable energy was greater in all treatments containing DDGS compared with CON (50.5 vs. 54.0 ± 1.08 Mcal/d for CON vs. DDGS, respectively). Net balance (milk plus tissue energy) per unit of dry matter was greater in CO (containing DDGS and oil) than CON (1.55 vs. 1.35 ± 0.06 Mcal/kg for CO vs. CON, respectively). Tissue energy was greater in DG and CO compared with CON (6.08, 7.04, and 3.16 ± 0.99 Mcal/d for DG, CO, and CON, respectively. Results of this study suggest that the addition of oil and calcium sulfate to diets containing DDGS may be a viable option to reduce methane production and in the case of oil also improve net energy balance in lactating dairy cows.

Narasin as a Manure Additive to Reduce Methane Production from Swine Manure

Abstract. High levels of methane production from swine operations have been associated with foam accumulation in deep-pit manure storage systems. This foam poses both a safety concern (i.e., flash fires) and operational challenges in managing stored manure. Mitigating methane production is one approach to controlling foam accumulation. In this study, swine manures obtained from three deep-pit storage barns in central Iowa were dosed with narasin to evaluate its inhibitory effects on methane and biogas production. Dose rates ranged from 0 to 3.0 mg narasin kg-1 manure. Overall, methane rates were reduced by 9% for each mg of narasin added per kg of manure, and this reduction was effective for up to 25 days. However, the inhibitory effect weakened with time such that no statistical difference in cumulative methane production between samples dosed with narasin and undosed controls could be detected after 120 days of incubation. In addition to methane rates, narasin addition reduced the degradation of total and volatile solids in the manure by 1.9% and 2.6%, respectively, for each mg of narasin added per kg of manure. Additional study treatments included sugar (10 g kg-1 manure) with and without narasin (1.5 mg narasin kg-1 manure). Results from this treatment showed that methane production was initially increased by the sugar addition, but the effect lasted less than six days, at which point cumulative methane production was similar to the control. When treated with both narasin and sugar, the inhibitory effect did not impact gas production during the sugar digestion phase but did reduce methane and biogas production thereafter. The addition of sugar and the rate of narasin addition caused changes to the microbial community as compared to the control. Overall, the results indicated that narasin can be an effective additive for reducing methane emission from swine manure, but further study is needed to recommend dosing frequency and to evaluate how continuous addition of manure impacts narasin effectiveness. Keywords: Biogas, Manure management, Manure treatment, Methane, Narasin, Swine manure, Swine production.

Effect of oxidizing and reducing agents in soil on methane production in Southeast Asian paddies

ABSTRACTMethane is one of the greenhouse gases emitted from paddy soil ecosystems and may induce global warming and climate change; therefore, mitigation options are urgently required to establish mitigation technology to reduce methane emission without affecting rice production. Methane is produced by a balance between oxidizing agents (such as iron) and reducing agents (easily decomposable soil organic matter), according to the so-called Takai theory. To evaluate options for mitigating methane production potential and to examine the applicability of the Takai theory in Southeast Asian paddy soils, 23 soil samples were collected from Thailand, Indonesia, Philippines, and Vietnam. These soil samples were anaerobically incubated to measure their methane production potential and examined to see whether their chemical properties, such as the ferrous, total iron, and organic matter contents, were correlated. We found a significant negative correlation between the methane production potential and the total iron content, and a positive correlation between the methane production potential and the hexose content, as an index for a soil’s easily decomposable organic matter content. The methane–C/CO2–C production ratio was also positively correlated with the mineralizable nitrogen/ferrous contents ratio, which indicated that the Takai theory, established for Japanese paddy soils, is also useful in Southeast Asian paddy soils and that the soil’s iron content is important to estimate the methane production potential.

Climate Clever Clovers: New Paradigm to Reduce the Environmental Footprint of Ruminants by Breeding Low Methanogenic Forages Utilizing Haplotype Variation.

Mitigating methane production by ruminants is a significant challenge to global livestock production. This research offers a new paradigm to reduce methane emissions from ruminants by breeding climate-clever clovers. We demonstrate wide genetic diversity for the trait methanogenic potential in Australia’s key pasture legume, subterranean clover (Trifolium subterraneum L.). In a bi-parental population the broadsense heritability in methanogenic potential was moderate (H2 = 0.4) and allelic variation in a region of Chr 8 accounted for 7.8% of phenotypic variation. In a genome-wide association study we identified four loci controlling methanogenic potential assessed by an in vitro fermentation system. Significantly, the discovery of a single nucleotide polymorphism (SNP) on Chr 5 in a defined haplotype block with an upstream putative candidate gene from a plant peroxidase-like superfamily (TSub_g18548) and a downstream lectin receptor protein kinase (TSub_g18549) provides valuable candidates for an assay for this complex trait. In this way haplotype variation can be tracked to breed pastures with reduced methanogenic potential. Of the quantitative trait loci candidates, the DNA-damage-repair/toleration DRT100-like protein (TSub_g26967), linked to avoid the severity of DNA damage induced by secondary metabolites, is considered central to enteric methane production, as are disease resistance (TSub_g26971, TSub_g26972, and TSub_g18549) and ribonuclease proteins (TSub_g26974, TSub_g26975). These proteins are good pointers to elucidate the genetic basis of in vitro microbial fermentability and enteric methanogenic potential in subterranean clover. The genes identified allow the design of a suite of markers for marker-assisted selection to reduce rumen methane emission in selected pasture legumes. We demonstrate the feasibility of a plant breeding approach without compromising animal productivity to mitigate enteric methane emissions, which is one of the most significant challenges to global livestock production.

Changes in rumen protozoal community by condensed tannin fractions of different molecular weights from a Leucaena leucocephala hybrid invitro.

To evaluate the effects of condensed tannins (CTs) fractions of differing molecular weights (MWs) from a Leucaena leucocephala hybrid-Rendang on the rumen protozoal community invitro. The effects of unfractionated CTs (F0) and CT fractions of different MWs (F1>F2>F3>F4>F5) on protozoal population and community were evaluated invitro using rumen microbes and ground guinea grass as the substrate. Higher-MW CT fractions F1 and F2 significantly (P<0·05) decrease the number of ciliate protozoa. The real-time PCR analysis showed that the total protozoa was significantly (P<0·05) lower in F0 and all CTs with fractions F1 and F2 having the lowest value. High-throughput sequencing of the partial 18S rRNA gene showed that the genus Entodinium significantly (P<0·05) decreased with increasing MWs of CT, whereas Anoplodinium-Diplodinium were significantly (P<0·05) increased. Inclusion of the highest MW CT fraction F1 decreased the relative abundance of the minor genera such as Eudiplodinium and Polyplastron compared to the control and CT fractions F2-F5. CTs of differing MWs could reduce and alter the rumen protozoa population in vitro. This effect was more pronounced for higher-MW CTs. The high MW CTs should be considered as a feed supplement in the ruminant diet to reduce the protozoal population which are known to be associated with methanogens as a means to mitigate methane production in the rumen.

Impact of feeding essential oils on feed fermentation and rumen microbial profile in crossbred cattle calves

The essential oils (EOs), viz. ajwain (Trachyspermum copticum, AjO), lemongrass (Cymbopogon citratus, LO), clove (Syzygium aromaticum) oleoresin (CO) and a blend (BEO) of the 3 were screened using in vitro gas production test for their potential to mitigate methane production. Inclusion of all the 3 EOs and BEO at the rate of 1.0 μl/ml of incubation medium resulted in a depression in total gas and methane production with a maximum reduction of 91.6 and 97.2% by BEO. Feed digestibility was significantly reduced by all the 3 EOs and BEO as compared to control but was similar among the 4 treatments. The level of total volatile fatty acids, acetic and propionic acids in fermented medium was significantly decreased by inclusion of EOs and BEO. Based on the results of these results, BEO was selected for the feeding trial. Ten crossbred cattle calves (average body weight, 68±5 kg) were divided into 2 groups of 5 animals each and subjected to 2 treatments i.e. diet without (control) and with BEO @ 0.1 mL/kg BW (treated). The diet comprised concentrate mixture (21.9%, CP and 71.1% TDN) and wheat straw in 50:50 ratio. There was no impact of BEO feeding on rumen metabolites and enzyme profile. As assessed by real time PCR, the population of protozoa and Ruminococcus albus reduced, whereas, bacteria, fungi, Fibrobacter succinogenes and Ruminococcus flavefaciens remained unaffected by BEO feeding. Methanogen population density tended to reduce by BEO feeding. The results clearly indicated that BEO exhibited antimethanogenic activity in in vitro system. By feeding BEO, the decreased population density of protozoa and methanogens in the rumen, the 2 major microbial groups involved in methanogenesis, also supported antimethnogenic property of BEO.

Effect of sulphate and blend of plant parts containing secondary metabolites on in vitro methanogenesis, digestibility and feed fermentation with buffalo rumen liquor

A blend of plant parts containing fruit of Phyllanthus emblica (amla), seed of Foeniculum vulgare (fennel) and seed of Trachyspermum ammi (ajwain) mixed in equal proportion (BP) was tested at 0, 10 and 20% of the substrate along with 0, 2.5 and 5% of sodium sulphate (S) for their effects on in vitro methane production and feed fermentation. Inclusion of combination of BP with S did not affect production of total gas, methane and feed digestibility. In vitro gas production was not influenced by any level of S, whereas, it increased linearly with increasing level of BP. Inhibition pattern of methane production (ml/g DM) was similar by inclusion of both S and BP and the inhibition was 21.3% by inclusion of BP20S5. In vitro true digestibility of feed was significantly increased by inclusion of both S and BP and was 10.9% higher with BP20S5 as compared to control (BP0S0). Total volatile fatty acids werenot affected by any of the treatments, whereas, acetate was increased and propionate and butyrate were significantly reduced resulting in increased acetate to propionate ratio. Ammonia production was not affected by inclusion of neither S nor BP. It may be summarized that the blend of amla, ajwain and fennel and sodium sulphate can be explored as feed additive to mitigate methane production with an additional benefit of improvement in feed digestibility.

Ginkgo fruit extract as an additive to modify rumen microbiota and fermentation and to mitigate methane production

Ginkgo fruit, an unused byproduct of the ginkgo nut industry, contains antimicrobial compounds known as anacardic acids. Two major cultivars of ginkgo, Kyuju (K) and Tokuro (T), were evaluated for their potential as a feed additive for ruminants. In batch culture, we incubated a mixture of hay and concentrate in diluted rumen fluid with or without 1.6% (fruit equivalent) ginkgo fruit extract. We conducted another series of batch culture studies to determine the dose response of fermentation. We also conducted continuous culture using the rumen simulation technique (RUSITEC) with cultivar K and carried out a pure culture study to monitor the sensitivity of 17 representative rumen bacterial species to ginkgo extract and component phenolics. Although both K and T extracts led to decreased methane and increased propionate production, changes were more apparent with K extract, and were dose-dependent. Total gas production was depressed at doses ≥3.2%, suggesting that 1.6% was the optimal supplementation level. In RUSITEC fermentation supplemented with 1.6% ginkgo K, methane decreased by 53% without affecting total gas or total VFA production, but with decreased acetate and increased propionate. Disappearance of dry matter, neutral detergent fiber, and acid detergent fiber were not affected by ginkgo, but ammonia levels were decreased. Quantitative PCR indicated that the abundance of protozoa, fungi, methanogens, and bacteria related to hydrogen and formate production decreased, but the abundance of bacteria related to propionate production increased. MiSeq analysis (Illumina Inc., San Diego, CA) confirmed these bacterial changes and identified archaeal community changes, including a decrease in Methanobrevibacter and Methanomassiliicoccaceae and an increase in Methanoplanus. Pure culture study results supported the findings for the above bacterial community changes. These results demonstrate that ginkgo fruit can modulate rumen fermentation toward methane mitigation and propionate enhancement via microbial selection.

Effect of inclusion of graded level of water hyacinth on in vitro gas production kinetics and chemical composition of alfalfa hay based beef cattle diets

The aim of this study was to evaluate the inclusion of water hyacinth (WH) as a possible substitution of alfalfa hay (AH) in diets of beef cattle on in vitro methane production, gas kinetics and chemical composition. AH in the diets was substituted by WH at 0% (T1, as a control), 25% (T2), 50% (T3), 75% (T4) and 100% (T5). Methane, CO2 and gas production parameters were recorded after 24 and 48h of incubation. NDF, condensed tannins and total phenolic compounds increased when AH was substituted. Likewise, the net gas production decreased linearly when AH was substituted. However, gas production rate among treatments were similar. Methane and CO2 production decreased linearly with inclusion of WH. These results indicate that WH arises as a promising alternative for mitigating methane production in ruminants.

Potential of tannin-rich plants for modulating ruminal microbes and ruminal fermentation in sheep.

The objective of this work was to study nutritional strategies for decreasing methane production by ruminants fed tropical diets, combining in vitro and in vivo methods. The in vitro approach was used to evaluate the dose effect of condensed tannins (CT) contained in leaves of Gliricidia sepium, Leucaena leucocephala, and Manihot esculenta (39, 75, and 92 g CT/kg DM, respectively) on methane production and ruminal fermentation characteristics. Tannin-rich plants (TRP) were incubated for 24 h alone or mixed with a natural grassland hay based on Dichanthium spp. (control plant), so that proportions of TRP were 0, 0.25, 0.5, 0.75, and 1.0. Methane production, VFA concentration, and fermented OM decreased with increased proportions of TRP. Numerical differences on methane production and VFA concentration among TRP sources may be due to differences in their CT content, with greater effects for L. leucocephala and M. esculenta than for G. sepium. Independently of TRP, the response to increasing doses of CT was linear for methane production but quadratic for VFA concentration. As a result, at moderate tannin dose, methane decreased more than VFA. The in vivo trial was conducted to investigate the effect of TRP on different ruminal microbial populations. To this end, 8 rumen-cannulated sheep from 2 breeds (Texel and Blackbelly) were used in two 4 × 4 Latin square designs. Diets were fed ad libitum and were composed of the same feeds used for the in vitro trial: control plant alone or combined with pellets made from TRP leaves at 44% of the diet DM. Compared to TRP, concentration of Ruminococcus flavefaciens was greater for the control diet and concentration of Ruminococcus albus was least for the control diet. The methanogen population was greater for Texel than for Blackbelly. By contrast, TRP-containing diets did not affect protozoa or Fibrobacter succinogenes numbers. Hence, TRP showed potential for mitigating methane production by ruminants. These findings suggest that TRP fed as pellets could be used to decrease methane production.

Influence of mangosteen peel powder as a source of plant secondary compounds on rumen microorganisms, volatile fatty acids, methane and microbial protein synthesis in swamp buffaloes

The objective of this experiment was to evaluate the effect of mangosteen peel powder (MSP) on rumen fermentation, nutrient digestibility and microbial population in swamp buffaloes (Bubalus bubalis) fed on a rice straw based diet. MSP is a fruit peel that contains plant secondary compounds (condensed tannins and saponins). Eight, rumen-fistulated 4-year old, male swamp buffaloes with 350±4kg live weight were randomly assigned to receive two dietary treatments (T1=non-supplementation of MSP and T2=supplementation of MSP at 100g/(head×day)) according to a t-test design. All animals were fed concentrate mixtures at 0.5% of body weight and rice straw was fed ad libitum for 37 days with the first 30 days for feed adaptation and voluntary feed intake measurement, while the last 7 days were for samples collection. The results revealed that there was no difference between treatments on dry matter intake and nutrient digestibility by MSP supplementation (P>0.05). Furthermore, MSP supplementation did not influence ruminal pH, temperature, ammonia nitrogen and blood urea nitrogen. Interestingly, propionic acid (C3) production was significantly increased by MSP supplementation (P<0.05) while total volatile fatty acids, acetic acid (C2) and butyric acid were similar between treatments. Moreover, C2:C3 ratio was reduced by MSP supplementation. In addition, estimated rumen methane was significantly reduced by MSP supplementation (P<0.05). Application of quantitative PCR to quantify cellulolytic bacteria (16S rRNA) targets revealed that MSP supplementation did not change population of Fibrobacter succinogenes and Ruminococcus albus (P>0.05) while total bacteria population were significantly increased by MSP supplementation. The Ruminococcus flavefaciens and methanogens population were significantly decreased as MSP were supplemented (P<0.05). Nitrogen intake, excretion (fecal and urine) and balance (absorption and retention) were similar between treatments whilst microbial nitrogen supply and efficiency of microbial protein synthesis were increased by MSP supplementation. In conclusion, supplementation of MSP as a source of plant secondary compounds exhibited no negative effect on feed intake, nutrient digestibility, ruminal fermentation characteristics, nutrient utilization and microbial protein synthesis. But rather, it could influence on rumen methanogenic population and hence, possibly mitigate methane production in swamp buffaloes fed on a rice straw based diet.

In vitro fermentation, digestibility and methane production of tropical perennial grass species

This study characterised 16 tropical perennial grass species in terms of in vitro methane output and related their digestibility and rumen fermentation with methane output. The grass samples were collected, dried in a forced oven, and ground and analysed for nutrient composition. In vitro gas production and organic matter digestibility (IVOMD) were determined using rumen fluid collected, strained and anaerobically prepared. A semi-automated system was used to measure gas production through in vitro incubation at 39°C. Anthephora argentea and Stipagrostis ciliate produced the highest concentration of methane in terms of g kg–1 digestible dry matter (DDM) and g kg–1 digestible organic matter (IVOMD). Cenchrus ciliaris, Setaria verticillata and Panicum coloratum produced the lowest (P &lt; 0.05) methane when expressed in terms of g kg–1 DDM and g kg–1 IVOMD. Ash, ether extract, non-fibrous carbohydrate, neutral and acid detergent insoluble nitrogen, and crude protein were negatively correlated with methane production. Methane production positively correlated with neutral and acid detergent fibre, cellulose and hemicellulose. It is important to focus on screening and selecting perennial grass with higher nitrogen content and low methane production to mitigate methane production under tropical conditions.