In vitro screening of various tropical foliages, seeds, fruits and medicinal plants for low methane and high ammonia generating potentials in the rumen

Assessing the combination efficiency of some unconventional feed resources with concentrates and Chloris gayana grass in mitigating ruminal methane production in vitro

In a preliminary in vitro study, leaves of Acacia nilotica, Prosopis juliflora, Cajanus cajan, Leucaena leucocephala and seed kernel of Mangifera indica were identified as potential candidates in mitigating ruminal methane (CH4) production. The objective of the current study was to investigate the combination efficiency of these unconventional feeds with concentrate mix (CM) or Chloris gayana grass in CH4 reduction. Two feed combinations in different proportions were incubated in vitro with buffered rumen fluid at Hohenheim Gas test. In combination 1, C. gayana and CM were included as basal substrates, while in combination 2, A. nilotica, P. juliflora, C. cajan, L. leucocephala or M. indica seed kernel were included as CH4 reducing supplements at different proportions. The CH4 reducing potentials of feed combinations were presented as the ratio of CH4 to net gas production and expressed as percentage (pCH4). The pCH4 for CM and C. gayana was 16.7% and 16.9%, respectively, while it ranged from 3.18% in A. nilotica to 13.1% in C. cajan. The pCH4 was reduced (p < 0.05) from 14.6% to 9.39% when A. nilotica was combined with CM. In combination of L. leucocephala or C. cajan with CM, the pCH4 (p < 0.05) was reduced from 16.5% and 16.6% with the lowest proportion to 15.1% and 15.2% with the highest inclusion rate respectively. The combination of C. gayana with L. leucocephala or C. cajan reduced (p < 0.05) the pCH4 from 16.3% and 16.4% to 15.1% and 14.9% respectively. The pCH4 was reduced (p < 0.05) from 13.4% to 7.60% when A. nilotica was combined with C. gayana. Estimated digestible organic matter (dOM) and metabolizable energy (ME) increased (p < 0.05) with increasing proportions of M. indica seed kernel with CM or C. gayana. In conclusion, the combination of the basal substrates with unconventional supplements resulted in CH4 reduction without affecting the dOM and ME at lower inclusion rates. Animal-based experiments await to validate in vitro findings.

The Effect of Monensin vs. Neem, and Moringa Extracts on Nutrient Digestibility, Growth Performance, Methane, and Blood Profile of Merino Lambs

Plant secondary compounds are potential rumen modifiers that can improve nutrient utilization in ruminant animals. This study evaluated the effect of Moringa (Moringa oleifera) and Neem (Azadirachta indica) leaf extracts on nutrient digestibility, growth performance, and enteric methane production in South African Mutton Merino lambs. Forty 4-month-old ram lambs with a mean body weight of 35 ± 2.2 kg were blocked by weight and from each block, lambs were randomly allocated into one of the following treatments: (i) diet only (fed a total mixed ration TMR-negative control), (ii) Monensin (fed TMR containing Monensin sodium, 15 mg/kg DM), (iii) Moringa (fed TMR, drenched with Moringa extract 50 mg/kg feed DM intake), and (iv) Neem (fed TMR, drenched with Neem extract 50 mg/kg DM intake). Extracts were administered via oral drenching at a concentration determined based on the previous week's feed intake. There were no differences in dry matter intake, average daily gain, feed conversion efficiency, digestibility, and nitrogen retention across the treatments. However, the extracts tended to reduce methane emitted both in g/head/day (p < 0.08) and g/ kg dry matter intake (p < 0.07). Extracts did not influence any of the blood metabolites in the ram lambs. Although the benefits of utilizing these medicinal plants as rumen modifiers under prolonged feeding conditions is justified, further evaluation is recommended to test Moringa and Neem leaf extracts at higher inclusion levels. Our research group is currently exploring a variety of phytogenic tools for the identification and standardization of key bioactive compounds linked to methane inhibition, in these leaf extracts.

Olgunlaşma Döneminin Rheum ribes L.’nin Potansiyel Besleme Değerine Etkisi

Bu çalışmanın amacı Rheum ribes L. ‘nin farklı olgunlaşma dönemlerinin kimyasal bileşiminine, kondanse tanen (KT) içeriğine, gaz ve metan üretimine, metabolik enerji (ME) ve organik madde sindirim derecesine (OMSD) etkisinin belirlenmesidir. Olgunlaşma dönemi kimyasal bileşimi, KT içeriğini, gaz ve metan üretimini, ME ve OMSD önemli derecede etkilemiştir (P&lt;0.05). Rheum ribes L.’nin kuru madde (KM), ham kül (HK), ham protein (HP), ham yağ (HY), KT, asit çözücülerde çözünmeyen lifli bileşikler (ADF), nötr çözücülerde çözünmeyen lifli bileşikleri (NDF) sırasıyla 92.73-98.64%, 6.11-14.15%, 8.81-19.12%, 1.94-3.04%, 10.47-14.72%, 36.99-53.98% and 24.88-37.63% aralıklarında belirlenmiştir. Rheum ribes L.’nin 24 saatlik gaz üretimi, metan üretimi 29.73-40.60 ml ve 2.63-5.50 ml aralığında belirlenmiştir. ME ve OMSD 6.97-9.87 MJ kg-1 KM ve 45.68-60.02% aralığında belirlenmiştir. Özet olarak olgunlaşma dönemi Rheum ribes L.’nin besleme değerini önemli ölçide etkilemiştir. Rheum ribes L. ‘nin özellikle HP, ME, OMSD olgunlaşma dönemi ilerledikçe azalmıştır. Rheum ribes L.’nin gaz üretimi, ME ve OMSD, ADF ve NDF içeriği ile önemli ve negatif korelasyon göstermiş, ham protein içeriği ile pozitif korelasyon sergilemiştir. Ek olarak Rheum ribes L.’nin ruminant hayvanların performansı ve besleme değerinin belirlenebilmesi için in vivo çalışmalara da ihtiyaç duyulmaktadır.

Chemical, mineral composition, in vitro ruminal fermentation and buffering capacity of some rangeland-medicinal plants

A diverse group of rangeland-medicinal plants are being used by ruminant whilst some of them have not been assessed for their nutritional value. This study was aimed to evaluate the chemical and mineral composition, buffering capacity, and in vitro fermentation of some rangeland-medicinal plants including Thymus kotschyanus, Ziziphora persica, Lallemantia royleana, and Scutellaria litwinowii in the family Lamiaceae, and Hypericum scabrum, in the family Hypericaceae. The results indicated that crude protein (CP) content ranged from 8.66% (S. litwinowii) to 12.17% of DM (H. scabrum). It was found that Z. persica had the highest potential gas production, metabolism energy (ME), relative feed value (RFV), and dry matter digestibility (DMD) values of 53.44 (mL 200-1 mg DM), 5.84 (MJ kg-1 DM), 170.66 and 70.88%, respectively. Mineral content differed among plants; Ca ranged from 5.79 to 41.96 g kg-1 DM. The concentrations of Ca, K, Mg, Fe, Zn, and Co were highest for L. royleana. Total volatile fatty acids (TVFA) and propionate concentrations were highest in the culture medium cultured with Z. persica, however, acetate, and butyrate were highest in H. scabrum. Acid-base buffering capacity was lower in T. kotschyanus and H. scabrum compared to other plants, while it was higher in S. litwinowii. Overall, it can be concluded that among plants evaluated in this study, Z. persica had higher nutritional value for sheep feeding.

Harnessing plant bioactivity for enteric methane mitigation in Australia

This review provides examples of the utilisation of plant bioactivity to mitigate enteric methane (CH4) emissions from the Australian ruminant production systems. Potential plant-based mitigation strategies that reduce CH4 without major impacts on forage digestibility include the following: (i) low methanogenic tropical and temperate grass, legume and shrub forage species, which offer renewable and sustainable solutions and are easy to adopt, but may have restricted geographical distribution or relatively high costs of establishment and maintenance; (ii) plant-based agricultural by-products including grape marc, olive leaves and fruit, and distiller’s grains that can mitigate CH4 and provide relatively cheap high-nutrient supplements, while offsetting the impact of agricultural waste, but their use may be limited due to unfavourable characteristics such as high protein and water content or cost of transport; (iii) plant extracts, essential oils and pure compounds that are abundant in Australian flora and offer exciting opportunities on the basis of in vitro findings, but require verification in ruminant production systems. The greatest CH4 mitigation potential based on in vitro assays come from the Australian shrubs Eremophila species, Jasminum didymium and Lotus australis (>80% CH4 reduction), tropical forages Desmanthus leptophyllus, Hetropogon contortus and Leucaena leucocephala (~40% CH4 reduction), temperate forages Biserrula pelecinus (70–90% CH4 reduction), perennial ryegrass and white clover (~20% CH4 reduction), and plant extracts or essential oils from Melaleuca ericifolia, B. pelecinus and Leptospermum petersonii (up to 80% CH4 reduction). Further research is required to confirm effectiveness of these plant-based strategies in vivo, determine optimal doses, practical modes of delivery to livestock, analyse benefit–cost ratios and develop pathways to adoption.

Role of Secondary Plant Metabolites on Enteric Methane Mitigation in Ruminants

The rumen microbiome plays a fundamental role in all ruminant species, it is involved in health, nutrient utilization, detoxification, and methane emissions. Methane is a greenhouse gas which is eructated in large volumes by ruminants grazing extensive grasslands in the tropical regions of the world. Enteric methane is the largest contributor to the emissions of greenhouse gases originating from animal agriculture. A large variety of plants containing secondary metabolites [essential oils (terpenoids), tannins, saponins, and flavonoids] have been evaluated as cattle feedstuffs and changes in volatile fatty acid proportions and methane synthesis in the rumen have been assessed. Alterations to the rumen microbiome may lead to changes in diversity, composition, and structure of the methanogen community. Legumes containing condensed tannins such as Leucaena leucocephala have shown a good methane mitigating effect when fed at levels of up to 30–35% of ration dry matter in cattle as a result of the effect of condensed tannins on rumen bacteria and methanogens. It has been shown that saponins disrupt the membrane of rumen protozoa, thus decreasing the numbers of both protozoa and methanogenic archaea. Trials carried out with cattle housed in respiration chambers have demonstrated the enteric methane mitigation effect in cattle and sheep of tropical legumes such as Enterolobium cyclocarpum and Samanea saman which contain saponins. Essential oils are volatile constituents of terpenoid or non-terpenoid origin which impair energy metabolism of archaea and have shown reductions of up to 26% in enteric methane emissions in ruminants. There is emerging evidence showing the potential of flavonoids as methane mitigating compounds, but more work is required in vivo to confirm preliminary findings. From the information hereby presented, it is clear that plant secondary metabolites can be a rational approach to modulate the rumen microbiome and modify its function, some species of rumen microbes improve protein and fiber degradation and reduce feed energy loss as methane in ruminants fed tropical plant species.

Effect of the addition of Enterolobium cyclocarpum pods and Gliricidia sepium forage to Brachiaria brizantha on dry matter degradation, volatile fatty acid concentration, and in vitro methane production

The purpose of this study was to determine the in vitro fermentation and methane (CH₄) production in the grass Brachiaria brizantha (B) alone or when mixed with Gliricidia sepium forage (G) and/or Enterolobium cyclocarpum pods (E). Theses substrates were incubated in the following proportions: B100 (B100%), B85E15 (B85% + E15%), B85G15 (B85% + G15%), B85GE15 (B85% + G7.5% + E7.5%), and B70GE30 (B70% + G15% + E15%). Dry matter degradation (DMD), volatile fatty acid (VFA) concentration, and CH₄ production were measured at 12, 24, and 48 h of incubation. Experimental design was a randomized complete block. At 48-h incubation, DMD ranged between 46.5 and 51.2% (P = 0.0015). The lowest cumulative gas production (CGP) was observed in B85E15 and B85G15 (160 mL CGP/g organic matter, on average). At 48 h, B85G15 and B100 produced 28.8 and 30.2 mg CH4/g DMD, respectively, while B85E15 or the mixtures, 33.5 mg CH₄/g DMD, on average (P ≤ 0.05). B85E15 and B70G30 had the highest concentration of total VFA (P ≤ 0.05). Results showed that B85E15 and B70GE30 favor DMD and increased total production of VFA and CH₄ at 48 h. Supplementing livestock feed with legume forages and pods allows improves the nutritional quality of the diet and the fermentation patterns.

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

Simple Summary

Methane 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.

Abstract

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.

In vitro screening of plants from the Brazilian Caatinga biome for methanogenic potential in ruminant nutrition

Thirty-nine plants naturally found in Brazilian Caatinga semiarid biome were screened using an in vitro fermentability testing focused in apparent organic matter digestibility (aOMD), gas, methane (CH₄), and short-chain fatty acid (SCFA) production. Three independent in vitro runs were carried out and plants were classified by CH₄ concentration as proportion of gas and per unit of apparent digested organic matter (aDOM). According to its CH₄ concentration on produced gas (mL/L), the plants were classified as low (> 110), medium (from 60 to 110), and high (< 60) anti-methanogenic potential. From evaluated plants, 3, 24, and 12 were classified as high, medium, and low anti-methanogenic potential. High anti-methanogenic potential plants Cnidoscolus phillacanthus (CnPh), Chloroleucon foliolosum (ChFo), and Anadenanthera macrocarpa (AnMa) produced 21.3, 34.3, and 35.9 mL CH₄/L of gas. Methane concentration for Myracrodruon urundeuva (MyUr) was 61.1 mL/L and classified as medium potential. However, CH₄ production per unit of aDOM was similar between MyUr and AnMa (3.35 and 2.68 mL/g, respectively). Molar proportions of acetate and propionate in SCFA produced by ChFo fermentation were 0.02 and 0.78 mmol/mol. Acetate to propionate ratios were 0.79, 0.03, 1.39, and 1.36 for CnPh, ChFo, AnMa, and MyUr, respectively. Greater aOMD were observed for Opuntia sp. and Calotropis procera (632 and 601 g/kg, respectively), which were classified as medium mitigating potential plants. AnMa, ChFo, CnPh, and MyUr are promising anti-methanogenic plants for ruminants. Selecting forages to feed ruminants in Caatinga is a potential strategy for enteric CH₄ emission reduction, and our in vitro results can support future research by indicating species to be evaluated in in vivo studies integrating mixed diets with performance, digestibility, and CH₄ production, yield, and intensity. Graphical abstract ᅟ.

Supplementation of Pelleted Hazel (Corylus avellana) Leaves Decreases Methane and Urinary Nitrogen Emissions by Sheep at Unchanged Forage Intake

This study is the first to quantify the effects of hazel (Corylus avellana) leaves on methane and urinary nitrogen emissions, digestibility, nitrogen and the energy balance of ruminants. Four experimental pellets were produced with 0, 30% and 60% hazel leaves, the latter also with 4% polyethylene glycol. Hazel leaves gradually replaced lucerne. The diet was composed of the pellets and grass hay (80%: 20%). Six adult sheep were allocated to all four treatments in a 6 × 4 crossover design. Including hazel leaves did not affect the feed intake, but it decreased the apparent digestibility of organic matter and fibre, especially at the high level. Methane emission was reduced by up to 25 to 33% per day, per unit of intake and per unit of organic matter digested. Urinary nitrogen excretion decreased by 33 to 72% with increasing levels of hazel leaves. The treatment with polyethylene glycol demonstrated that tannins in hazel leaves caused significant shares of the effects. In conclusion, the current results indicated a significant potential of hazel leaves as forage for ruminants to mitigate methane and urinary nitrogen emissions. Even high dietary hazel leaf proportions were palatable. The lower digestibility needs to be compensated with easily digestible diet ingredients.

Differences in the nutrient concentrations, in vitro methanogenic potential and other fermentative traits of tropical grasses and legumes for beef production systems in northern Australia

BACKGROUND

In northern Australia, beef cattle grazed extensively on tropical rangelands are responsible for 5% of the nation's total greenhouse gas emissions. Methane (CH₄ ) is a potent greenhouse gas and in grazing ruminants might be mitigated by selecting forages that, when consumed, produce less CH₄ when fermented by rumen microbes. This study examined variability in the in vitro fermentation patterns, including CH₄ production of selected tropical grasses and legumes, to identify candidates for CH₄ mitigation in grazing livestock in northern Australia.

RESULTS

Nutritive values and fermentation parameters varied between plant species and across seasons. Grasses with a relatively low methanogenic potential were Urochloa mosambicensis (wet summer), Bothriochloa decipiens (autumn), Sorghum plumosum (winter) and Andropogon gayanus (spring), while the legumes were Calliandra calothyrsus (wet summer and autumn), Stylosanthes scabra (winter) and Desmanthus leptophyllus (spring). There was some correlation between CH₄ production and overall fermentation (volatile fatty acid concentrations) in grasses (R² = 0.67), but not in legumes (R² = 0.01) and there were multiple plants that had lower CH₄ not associated with reduction in microbial activity.

CONCLUSION

Differences in nutrient concentrations of tropical grasses and legumes may provide opportunities for productive grazing on these pastures, while offering some CH₄ mitigation options in the context of northern Australian extensive beef farming systems. © 2017 Society of Chemical Industry.

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.

Role of anaerobic fungi in wheat straw degradation and effects of plant feed additives on rumen fermentation parameters in vitro

In the present study, rumen microbial groups, i.e. total rumen microbes (TRM), total anaerobic fungi (TAF), avicel enriched bacteria (AEB) and neutral detergent fibre enriched bacteria (NEB) were evaluated for wheat straw (WS) degradability and different fermentation parameters in vitro. Highest WS degradation was shown for TRM, followed by TAF, NEB and least by AEB. Similar patterns were observed with total gas production and short chain fatty acid profiles. Overall, TAF emerged as the most potent individual microbial group. In order to enhance the fibrolytic and rumen fermentation potential of TAF, we evaluated 18 plant feed additives in vitro. Among these, six plant additives namely Albizia lebbeck, Alstonia scholaris, Bacopa monnieri, Lawsonia inermis, Psidium guajava and Terminalia arjuna considerably improved WS degradation by TAF. Further evaluation showed A. lebbeck as best feed additive. The study revealed that TAF plays a significant role in WS degradation and their fibrolytic activities can be improved by inclusion of A. lebbeck in fermentation medium. Further studies are warranted to elucidate its active constituents, effect on fungal population and in vivo potential in animal system.

Methanogenic potential of forages consumed throughout the year by cattle in a Sahelian pastoral area

Methane (CH4) emission from ruminants in African pastoral systems may be affected by intake and type of plants, which vary highly between rainy and dry seasons. In each of two sites located in the semiarid Sahelian area of Senegal, three Gobra zebus were monitored throughout 1 year. A representative sample of their diet was obtained once every month. Diet was mainly composed of grasses, herbaceous legumes, tree and shrub foliage and pods, and dried forage residues. CH4 production and volatile fatty acid (VFA) concentration, which reflects VFA production, were determined in vitro. Crude protein, neutral detergent fibre (NDF) and acid detergent fibre were measured by near-infrared spectrophotometry. CH4 production varied between 24.6 and 35.2 mL/g forage dry matter (DM), being minimal in August (rainy season) and maximal in February (dry season). Seasonal difference disappeared when CH4 was expressed in mL/g NDF. The acetate : propionate ratio varied in the same way as CH4 (3.2 and 4.6 in August and February, respectively); VFA concentration was minimum in March and maximum in September (69.2 and 77.4 mmol/L, respectively). CH4 production was closely related to dietary NDF content (r = 0.82) and to acetate : propionate ratio (r = 0.96). For six successive periods (February to July), plant categories constituting the diet were incubated separately. Reconstituting the CH4 production and VFA concentration in the diet on the basis of the proportion of plant components gave values similar to those of the global diet (33.4 and 34.2 mL CH4/g DM and 75.9 and 70.9 mmol VFA/L, respectively). This result suggests the absence of interaction among plant components on rumen fermentation.

In vitro fermentability and methane production of some alternative forages in Australia

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

In vitro methane and gas production characteristics of Eragrostis trichopophora substrate supplemented with different browse foliage

An in vitro gas production study was conducted to evaluate the potential of six browse species (high, medium and low condensed tannin concentrations) collected from the Kalahari Desert as antimethanogenic additives to an Eragrostis trichopophora-based substrate. The browse species studied were Acacia luederitzii, Monechma incanum, Acacia erioloba, Acacia haematoxylon, Olea europaea and Acacia mellifera. The edible forage dry matter of the browse species were incubated with Eragrostis trichopophora in a 30 : 70 (w/w) ratio by adding 40 mL of a buffered rumen fluid at 39°C for 48 h. Gas and methane production at different time intervals after incubation were determined whereas the volatile fatty acids concentration was evaluated after 48 h. Acacia luederitzii and M. incanum foliage decreased methane production by more than 50%, but simultaneously decreased digestibility, and rumen fermentation parameters such as volatile fatty acids concentration. Tannin extracts from A. luederitzii could possibly be used as a dietary alternative to reduce methane production; however, there is a need to determine an optimum level of inclusion that may not compromise the efficiency of rumen fermentation and overall digestibility of the diet.

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.

Potential of tannin-rich plants, Leucaena leucocephala, Glyricidia sepium and Manihot esculenta, to reduce enteric methane emissions in sheep

An in vivo trial was conducted in sheep to investigate the effect of three tropical tannin-rich plants (TRP) on methane emission, intake and digestibility. The TRP used were leaves of Glyricidia sepium, Leucaena leucocephala and Manihot esculenta that contained, respectively, 39, 75 and 92 g condensed tannins/kg DM. Methane was determined with the sulphur hexafluoride tracer technique. Eight rumen-cannulated sheep of two breeds (four Texel, four Blackbelly) were used in two 4 × 4 Latin square designs. Four experimental diets were tested. They consisted in a tropical natural grassland hay based on Dichanthium spp. fed alone (C) or in association with G. sepium (G), L. leucocephala (L) or M. esculenta (M) given as pellets at 44% of the daily ration. Daily organic matter intake was higher in TRP diets (686, 984, 1054 and 1186 g/day for C, G, L and M respectively; p < 0.05) while apparent organic matter total tract digestibility was not affected (69.9%, 62.8%, 65.3% and 64.7% for C, G, L and M respectively; p > 0.05). Methane emission was 47.1, 44.9, 33.3 and 33.5 g/kg digestible organic matter intake for C, G, L and M, respectively, and was significantly lower (p < 0.05) for L and M than for G and C. Our results confirm the potential of some TRP to reduce methane production. The strong decrease in methane and the increase in intake with TRPs may be due to their presentation as pellets.

Effect of Tannin and Species Variation on In vitro Digestibility, Gas, and Methane Production of Tropical Browse Plants

Nineteen tanniferous browse plants were collected from South Africa to investigate their digestibility, gas production (GP) characteristics and methane production. Fresh samples were collected, dried in forced oven, and ground and analyzed for nutrient composition. In vitro GP and in vitro organic matter digestibility (IVOMD) were determined using rumen fluid collected, strained and anaerobically prepared. A semi- automated system was used to measure GP by incubating the sample in a shaking incubator at 39°C. There was significant (p<0.05) variation in chemical composition of studied browses. Crude protein (CP) content of the species ranged from 86.9 to 305.0 g/kg dry matter (DM). The neutral detergent fiber (NDF) ranged from 292.8 to 517.5 g/kg DM while acid detergent fiber (ADF) ranged from 273.3 to 495.1 g/kg DM. The ash, ether extract, non-fibrous carbohydrate, neutral detergent insoluble nitrogen, and acid detergent insoluble nitrogen and CP were negatively correlated with methane production. Methane production was positively correlated with NDF, ADF, cellulose and hemi-cellulose. Tannin decreased GP, IVOMD, total volatile fatty acid and methane production. The observed low methanogenic potential and substantial ammonia generation of some of the browses might be potentially useful as rumen manipulating agents. However, a systematic evaluation is needed to determine optimum levels of supplementation in a mixed diet in order to attain a maximal depressing effect on enteric CH4 production with a minimal detrimental effect on rumen fermentation of poor quality roughage based diet.

Effects of tropical high tannin non legume and low tannin legume browse mixtures on fermentation parameters and methanogenesis using gas production technique

In vitro experiments were conducted to evaluate the suitability of several mixtures of high tanniniferous non legumes with low tanniniferous legumes on in vitro gas production (IVGP), dry matter degradation, Ammonia-N, methane production and microbial population. Eight treatments were examined in a randomized complete block design using four non-legumes and two legumes (Carallia integerrima×Leucaena leucocephala (LL) (Trt 1), C. integerrima×Gliricidia sepium (GS) (Trt 2), Aporosa lindeliyana×LL (Trt 3), A. lindeliyana×GS (Trt 4), Ceiba perntandra×LL (Trt 5), C. perntandra×GS (Trt 6), Artocarpus heterophyllus×LL (Trt 7), A. heterophyllus×GS (Trt 8). The condensed tannin (CT) content of non legumes ranged from 6.2% (Carallia integerrima) to 4.9% (Ceiba perntandra) while the CT of legumes were 1.58% (Leucaena leucocephala) and 0.78% (Gliricidia sepium). Forage mixtures contained more than 14% of crude protein (CP) while the CT content ranged from 2.8% to 4.0% respectively. Differences (p<0.05) were observed in in vitro gas production (IGVP) within treatments over a 48 h period dominated by C. perntandra×G. sepium (Trt 6). The net gas production (p<0.05) was also high with Trt6 followed by A. heterophyllus×L. leucocephala (Trt 7) and A. heterophyllus×G. sepium (Trt 8). Highest (p>0.05) NH3-N (ml/200 mg DM) production was observed with the A. heterophyllus×G. sepium (Trt 8) mixture which may be attributed with it's highest CP content. The correlation between IVGP and CT was 0.675 while IVGP and CP was 0.610. In vitro dry matter degradation (IVDMD) was highest in Trt 8 as well. Methane production ranged from 2.57 to 4.79 (ml/200 mg DM) to be synonimous with IVGP. A higher bacteria population (p<0.05) was found in C. perntandra×G. sepium (Trt 6) followed by Artocarpus heterophyllus+G. sepium (Trt 8) and the same trend was observed with the protozoa population as well. The results show that supplementing high tannin non leguminous forages by incremental substitution of legume forage increased gas production parameters, NH3-N, IVDMD and microbial population in the fermentation liquid. Methane production was not significantly affected by the presence of CT or different levels of CP in forage mixtures. Among non legumes, Ceiba perntandra and Artocarpus heterophyllus performed better in mixture with L. leucocephala and G. sepium.

Evaluation of the nutritive value of muiumba (Baikiaea plurijuga) seeds: chemical composition, in vitro organic matter digestibility and in vitro gas production

One of the main constraints hindering the increase of animal production in semi-arid regions of Africa is the inadequate supply of nutrients during the dry season. Incorporation of alternative feed resources in ruminant diets during this period could be a viable approach to overcome these limitations. The objective of this study was to evaluate the nutritive value of muiumba (Baikiaea plurijuga) tree seeds as an alternative nutrient source for ruminants. Muiumba seeds were compared to other eight feedstuffs including two cereal grains (corn and oat), two wheat by-products (wheat bran and distilled wheat) and four protein meals (coconut meal, sunflower meal, soybean meal and rapeseed meal) as to its chemical composition, in vitro organic matter digestibility (IVOMD) and in vitro gas production. The moderate crude protein concentrations (145 g/kg DM) of muiumba seeds indicate that this feedstuff could not be used as a protein supplement, contrarily to the majority of multipurpose tree seeds. Although the starch content was scarce (15 g/kg DM), the low neutral detergent fibre (235 g/kg DM), low molecular weight sugar (76.1 g/kg DM) and non-starch polysaccharide (510.5 g/kg DM) contents indicate that this feedstuff has potential feeding value. This was confirmed by the IVOMD (0.770) and by the data provided by the in vitro gas production showing that muiumba seeds had high (P < 0.05) maximum gas production and fractional fermentation rates, suggesting that these seeds are characterized by a highly fermentable fraction.

Eremophila glabra reduces methane production and methanogen populations when fermented in a Rusitec

Eremophila glabra Juss. (Scrophulariaceae), a native Australian shrub, has been demonstrated to have low methanogenic potential in a batch in vitro fermentation system. The present study aimed to test longer-term effects of E. glabra on rumen fermentation characteristics, particularly methane production and the methanogen population, when included as a component of a fermentation substrate in an in vitro continuous culture system (Rusitec). E. glabra was included at 150, 250, 400 g/kg DM (EG15, EG25, and EG40) with an oaten chaff and lupin-based substrate (control). Overall, the experiment lasted 33 days, with 12 days of acclimatization, followed by two periods during which fermentation characteristics (total gas, methane and VFA productions, dry matter disappearance, pH) were measured. The number of copies of genes specifically associated with total bacteria and cellulolytic bacteria (16S rRNA gene) and total ruminal methanogenic archaeal organisms (the methyl coenzyme M reductase A gene (mcrA)) was also measured during this time using quantitative real-time PCR. Total gas production, methane and volatile fatty acid concentrations were significantly reduced with addition of E. glabra. At the end of the experiment, the overall methane reduction was 32% and 45% for EG15 and EG25 respectively, compared to the control, and the reduction was in a dose-dependent manner. Total bacterial numbers did not change, but the total methanogen population decreased by up to 42.1% (EG40) when compared to the control substrate. The Fibrobacter succinogenes population was reduced at all levels of E. glabra, while Ruminococcus albus was reduced only by EG40. Our results indicate that replacing a portion of a fibrous substrate with E. glabra maintained a significant reduction in methane production and methanogen populations over three weeks in vitro, with some minor inhibition on overall fermentation at the lower inclusion levels.

In vitro fermentation characteristics and effective utilisable crude protein in leaves and green pods of Moringa stenopetala and Moringa oleifera cultivated at low and mid-altitudes

This study was conducted to assess the in vitro nutrient digestibility and utilisation of leaves and green pods of two Moringa species in supplementing the feed of ruminant animals during the dry season. Samples were analysed for proximate nutrients using official methods. The metabolisable energy (ME), organic matter digestibility (OMD) and effective utilisable crude protein (uCP) were estimated using the Hohenheim in vitro gas test method. Gas volume in Moringa stenopetala leaves and green pods was generally higher than those of Moringa oleifera. Gas volume for leaves was similar between low and mid-altitudes but was higher for green pods at mid-altitude. M. stenopetala leaves contained significantly higher ME (9.8 MJ/kg DM) and OMD (75%) than those of M. oleifera. Similarly, M. stenopetala green pods had higher ME and OMD values than those of M. oleifera. For green pods, the ME and OMD values were significantly higher at mid-altitude than those at low altitude although these values for leaves were similar between both altitudes. Moringa oleifera leaves had higher effective uCP than those of M. stenopetala. Nevertheless, the effective uCP was higher for green pods of M. stenopetala than those of M. oleifera. The effective uCP for leaves cultivated at mid-altitude was slightly higher than those at low altitude. This study suggested that leaves and green pods could be used as alternative energy and protein supplements for tropical ruminants, particularly during dry periods. It was further concluded that leaves were generally better in nutrient compositions and in vitro nutrient digestibility characteristics than green pods.

Effects of species-diverse high-alpine forage on in vitro ruminal fermentation when used as donor cow's feed or directly incubated

Alpine forages are assumed to have specific effects on ruminal digestion when fed to cattle. These effects were investigated in an experiment from two perspectives, either by using such forages as a substrate for incubation or as feed for a rumen fluid donor cow. In total, six 24-h in vitro batch culture runs were performed. Rumen fluid was collected from a non-lactating donor cow after having grazed pastures at ∼2000 m above sea level for 2, 6 and 10 weeks. These 'alpine runs' were compared with three lowland samplings from before and 2 and 6 weeks after the alpine grazing where a silage-concentrate mix was fed. In each run, nine replicates of four forages each were incubated. These forages differed in type and origin (alpine hay, lowland ryegrass hay, grass-maize silage mix, pure hemicellulose) as well as in the content of nutrients. Concentrations of phenolic compounds in the incubated forages were (g/kg dry matter (DM)): 20 (tannin proportion: 0.47), 8 (0.27), 15 (0.52) and 0 (0), respectively. Crude protein was highest in the silage mix and lowest with hemicellulose, whereas the opposite was the case for fiber. The total phenol contents (g/kg DM) for the high altitude and the lowland diet of the donor cow were 27 (tannins: 0.50 of phenols) and 12 (0.27), respectively. Independent of the origin of the rumen fluid, the incubation with alpine hay decreased (P < 0.05) bacterial counts, fermentation gas amount, volatile fatty acid (VFA) production as well as ammonia and methane concentrations in fermentation gas (the latter two being not lower when compared with hemicellulose). Alpine grazing of the cow in turn increased (P < 0.001) bacterial counts and, to a lesser extent, acetate proportion compared with lowland feeding. Further, alpine grazing decreased protozoal count (P < 0.05) and VFA production (P < 0.001) to a small extent, whereas methane remained widely unchanged. There were interactions (P < 0.05) between forage type incubated and feeding period of the donor cow in protozoal counts, acetate:propionate ratio, fermentation gas production and its content of methane, in vitro organic matter digestibility and metabolizable energy. Although increased phenolic compounds were the most consistent common property of the applied alpine forages, a clear attribution to certain effects was not possible in this study. As a further result, adaptation (long-term for donor cow, short term for 24 h incubations) appears to influence the expression of alpine forage effects in ruminal fermentation.

Feeding of tropical trees and shrub foliages as a strategy to reduce ruminal methanogenesis: studies conducted in Cuba

The aim of this paper was to present the main results obtained in Cuba on the effects of feeding tropical trees and shrubs on rumen methanogenesis in animals fed with low quality fibrous diets. More than 20 tree and shrub foliages were screened for phytochemicals and analyzed for chemical constituents. From these samples, seven promising plants (Samanea saman, Albizia lebbeck, Tithonia diversifolia, Leucaena leucocephala, Trichantera gigantea, Sapindus saponaria, and Morus alba) were evaluated for methane reduction using an in vitro rumen fermentation system. Results indicated that the inclusion levels of 25% of Sapindo, Morus, or Trichantera foliages in the foliages/grass mixtures (grass being Pennisetum purpureum) reduced (P < 0.01) methane production in vitro when compared to Pennisetum alone (17.0, 19.1, and 18.0 versus 26.2 mL CH(4)/g fermented dry matter, respectively). It was demonstrated that S. saman, A. lebbeck, or T. diversifolia accession 23 foliages when mixed at the rate of 30% in Cynodon nlemfuensis grass produced lower methane compared to the grass alone. Inclusion levels of 15% and 25% of a ruminal activator supplement containing 29% of L. leucocehala foliage meal reduced methane by 37% and 42% when compared to the treatment without supplementation. In vivo experiment with sheep showed that inclusion of 27% of L. leucocephala in the diet increased the DM intake but did not show significant difference in methane production compared to control diet without this foliage. The results of these experiments suggest that the feeding of tropical tree and shrub foliages could be an attractive strategy for reduction of ruminal methanogenesis from animals fed with low-quality forage diets and for improving their productivity.

In vitro evaluation, in vivo quantification, and microbial diversity studies of nutritional strategies for reducing enteric methane production

The main objective of the present work was to study nutritive strategies for lessening the CH(4) formation associated to ruminant tropical diets. In vitro gas production technique was used for evaluating the effect of tannin-rich plants, essential oils, and biodiesel co-products on CH(4) formation in three individual studies and a small chamber system to measure CH(4) released by sheep for in vivo studies was developed. Microbial rumen population diversity from in vitro assays was studied using qPCR. In vitro studies with tanniniferous plants, herbal plant essential oils derived from thyme, fennel, ginger, black seed, and Eucalyptus oil (EuO) added to the basal diet and cakes of oleaginous plants (cotton, palm, castor plant, turnip, and lupine), which were included in the basal diet to replace soybean meal, presented significant differences regarding fermentation gas production and CH(4) formation. In vivo assays were performed according to the results of the in vitro assays. Mimosa caesalpineaefolia, when supplemented to a basal diet (Tifton-85 hay Cynodon sp, corn grain, soybean meal, cotton seed meal, and mineral mixture) fed to adult Santa Ines sheep reduced enteric CH(4) emission but the supplementation of the basal diet with EuO did not affect (P > 0.05) methane released. Regarding the microbial studies of rumen population diversity using qPCR with DNA samples collected from the in vitro trials, the results showed shifts in microbial communities of the tannin-rich plants in relation to control plant. This research demonstrated that tannin-rich M. caesepineapholia, essential oil from eucalyptus, and biodiesel co-products either in vitro or in vivo assays showed potential to mitigate CH(4) emission in ruminants. The microbial community study suggested that the reduction in CH(4) production may be attributed to a decrease in fermentable substrate rather than to a direct effect on methanogenesis.

Decrease of ruminal methane production in Rusitec fermenters through the addition of plant material from rhubarb (Rheum spp.) and alder buckthorn (Frangula alnus)

Roots of rhubarb (Rheum spp.) and bark of alder buckthorn (Frangula alnus) were tested as feed additives for decreasing ruminal methane production released from anaerobic fermentation of a forage-based diet in a rumen-simulating fermenter (Rusitec). Sixteen fermentation units (vessels) were set up for the experiment lasting 19 d. Treated vessels were supplied with 1g/d of rhubarb or alder buckthorn (4 vessels per plant species); another 4 vessels received 12 microM sodium monensin (positive control), and the remaining 4 vessels were controls (no additive). Upon termination of the experimental period, batch cultures were inoculated with the liquid contents of the vessels for examining in vitro fermentation kinetics of cellulose, starch, barley straw, and the same substrate used in the Rusitec cultures. Monensin induced changes in fermentation in agreement with those reported in the literature, and inocula from those cultures decreased the fermentation rate and total gas produced in the gas kinetics study. Rhubarb decreased methane production, associated with limited changes in the profile of volatile fatty acids throughout the duration of the study, whereas digestibility and total volatile fatty acids production were not affected. Rhubarb inocula did not affect gas production kinetics except for cellulose. Alder buckthorn decreased only methane concentration in fermentation gas, and this effect was not always significant. The use of rhubarb (milled rhizomes of Rheum spp.) in the diets of ruminants may effectively modulate ruminal fermentation by abating methane production, thus potentially involving productive and environmental benefits.

Exploring the anthelmintic properties of Australian native shrubs with respect to their potential role in livestock grazing systems

We measured in vitro anthelmintic activity in extracts from 85 species of Australian native shrub, with a view to identifying species able to provide a degree of worm control in grazing systems. Approximately 40% of the species showed significant activity in inhibiting development of Haemonchus contortus larvae. The most active extracts showed IC50 values of 60-300 microg/ml. Pre-incubation with polyvinylpolypyrrolidine removed the activity from some extracts, implicating tannins as the bioactive agent, while in other cases the pre-incubation had no effect, indicating the presence of other anthelmintic compounds. Plant reproductive maturity (onset of flowering or fruiting) was associated with increasing anthelmintic activity in some species. Variability was observed between plants of the same species growing in different environments, while variation between individual plants of the same species within a single field suggests the existence of distinct chemotypes. Significant activity against adult H. contortus worms in vitro was also demonstrated in a limited number of extracts tested against this life stage. Our study indicates that there is potential for Australian native shrubs to play an anthelmintic role in grazing systems, and highlights some plant biology factors which will need to be considered in order to maximize any anthelmintic effects.

Efficiency of Sesbania sesban and Acacia angustissima in limiting methanogenesis and increasing ruminally available nitrogen in a tropical grass-based diet depends on accession

Novel strategies to improve nutrient-poor tropical diets for ruminants should aim to increase feeding value and, simultaneously, reduce emissions of the greenhouse gas methane. Both aims were addressed in the present in vitro experiment when supplementing a low quality, tropical grass (Brachiaria humidicola; Centro Internacional de Agricultura Tropical accession number 6133) with foliage from various leguminous multi-purpose shrubs, all of them containing plant secondary metabolites in different concentrations. In detail, foliage of Acacia angustissima from the International Livestock Research Institute ( ILRI; accessions no. 459 and 15132), Sesbania sesban (ILRI 10865 and 15019), Samanea saman (ILRI 14884), and leafy crop residues of the grain legume Cajanus cajan (ILRI 16555) were supplemented at 200 g/kg dry matter. Additionally, a combination of C. cajan and S. sesban 10865 was tested. Effects on methanogenesis, ruminal nitrogen turnover and other fermentation traits were determined with the rumen simulation technique Rusitec. All supplements enhanced the fermentable nutrient supply, especially ruminally degradable crude protein, and improved the calculated microbial efficiency in nitrogen utilisation. Methanogenesis was limited by one accession of S. sesban (10865) and, less clearly, by one A. angustissima accession (459), while the other supplements remained ineffective. The first mentioned accessions proved to be far richer in several plant secondary metabolites, especially saponins and tannins. Provided in combination, C. cajan and S. sesban 10865 supported each other in their effects on nitrogen usage and total methane release. Accordingly, a combination strategy might provide, after being verified in vivo, a particularly promising option to improve low quality, tropical diets at limited environmental impact thus facilitating its adoption by stakeholders.