A new perspective on the use of plant secondary metabolites to inhibit methanogenesis 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.

In vitro fermentation end-products and rumen microbiome as influenced by microencapsulated phytonutrient pellets (LEDRAGON) supplementation

The objective of this study was to investigate the effect of microencapsulated bioactive compounds from lemongrass mixed dragon fruit peel pellet (MiEn-LEDRAGON) supplementation on fermentation characteristics, nutrient degradability, methane production, and the microbial diversity using in vitro gas production technique. The study was carried out using a completely randomized design (CRD) with five levels of MiEn-LEDRAGON supplementation at 0, 1, 2, 3, and 4% of the total dry matter (DM) substrate. Supplementation of MiEn-LEDRAGON in the diet at levels of 3 or 4% DM resulted in increased (p < 0.05) cumulative gas production at 96 hours (h) of incubation time, reaching up to 84.842 ml/ 0.5 g DM. Furthermore, supplementation with 3% MiEn-LEDRAGON resulted in higher in vitro nutrient degradability and ammonia-nitrogen concentration at 24 h of the incubation time when compared to the control group (without supplementation) by 5.401% and 11.268%, respectively (p < 0.05). Additionally, supplementation with MiEn-LEDRAGON in the diet led to an increase in the population of Fibrobacter succinogenes at 24 h and Butyrivibrio fibrisolvens at 12 h, while decreasing the population of Ruminococcus albus, Ruminococcus flavefaciens, and Methanobacteriales (p < 0.05). Moreover, supplementation of MiEn-LEDRAGON in the diet at levels of 2 to 4% DM resulted in a higher total volatile fatty acids (VFA) at 24 h, reaching up to 73.021 mmol/L (p < 0.05). Additionally, there was an increased proportion of propionic acid (C3) and butyric acid (C4) at 12 h (p < 0.05). Simultaneously, there was a decrease in the proportion of acetic acid (C2) and the ratio of acetic acid to propionic acid (C2:C3), along with a reduction of methane (CH4) production by 11.694% when comparing to the 0% and 3% MiEn-LEDRAGON supplementation (p < 0.05). In conclusion, this study suggests that supplementing MiEn-LEDRAGON at 3% of total DM substrate could be used as a feed additive rich in phytonutrients for ruminants.

Microencapsulation of lemongrass and mangosteen peel as phytogenic compounds to gas kinetics, fermentation, degradability, methane production, and microbial population using in vitro gas technique

The purpose of the current study was to evaluate the impact of various doses of microencapsulated lemongrass and mangosteen peel (MELM) on gas dynamics, rumen fermentation, degradability, methane production, and microbial population in in vitro gas experiments. With five levels of microencapsulated-phytonutrient supplementation at 0, 1, 2, 3, and 4% of substrate, 0.5 g of roughage, and a concentrate ratio of 60:40, the trial was set up as a completely randomized design. Under investigation, the amount of final asymptotic gas volume was corresponding responded to completely digested substrate (b) increased cubically as a result of the addition of MELM (P < 0.01) and a cubic rise in cumulative gas output. The amount of MELM form did not change the pH and NH3-N concentration of the rumen after 12 and 24 h of incubation. However, methane production during 24 h of incubation, the levels were cubically decreased with further doses of MELM (P < 0.01) at 12 h of incubation. Increasing the dosage of MELM supplementation at 2% DM resulted in a significant increase in the digestibility of in vitro neutral detergent fiber (IVNDF) and in vitro true digestibility (IVTD) at various incubation times (P < 0.05), but decreased above 3% DM supplementations. Moreover, the concentration of propionic acid (C3) exhibited the variations across the different levels of MELM (P < 0.05), with the maximum concentration obtained at 2% DM. The populations of Fibrobacter succinogenes, Ruminococcus albus, Ruminococcus flavefaciens, and Megasphaera elsdenii revealed a significant increase (P < 0.05), while the quantity of Methanobacteriales decreased linearly with increasing doses of MELM. In conclusion, the inclusion of MELM at a concentration of 2% DM in the substrate which could enhance cumulative gas production, NDF and true digestibility, C3 production, and microbial population, while reducing methane concentration and Methanobacterial abundance.

Efficacy of Salvia officinalis Shrub as a Sustainable Feed Additive for Reducing Ruminal Methane Production and Enhancing Fermentation in Ruminants

The objective of this study was to evaluate the effects of the inclusion of dried Salvia officinalis (SO) shrub leaves on nutrient degradability, ruminal in vitro fermentation, gas production (GP), methane (CH4), and carbon dioxide (CO2) productions. Dried and ground SO shrub leaves were included at 0% (control), 0.5%, 1%, 1.5%, and 2% DM of a diet consisting of (per kg DM) 500 g concentrate feed mixture, 400 g berseem hay, and 100 g rice straw. The diet was incubated for 48 h. The asymptotic GP and the rate of GP changed linearly and quadratically (p < 0.01), with the highest GP observed at 1% inclusion of SO and then decreasing thereafter with greater inclusion (i.e., 1.5% and 2%), while CH4 production and its rate decreased linearly (p < 0.01) with all levels of SO inclusion. A linear increase in CO2 production and its rate was also found with an increasing level of SO inclusion in the diet (p < 0.05). Furthermore, the degradability of DM, NDF, and the concentration of total short-chain fatty acids and acetate changed linearly and quadratically, with the greatest being found at 1% SO inclusion and then steadily declining after (p < 0.01) with the 1.5% and 2% inclusion levels. Meanwhile, the propionate, NH3-N, and microbial crude protein levels showed similar trends, with the plateau found at 1% inclusion of SO, where there was no change in butyrate concentration. Moreover, the pH, metabolizable energy, and partitioning factor (PF24) also changed linearly and quadratically (p < 0.05), where the pH and PF24 were considerably reduced and ME increased with a 1% inclusion of SO (p < 0.05). In summary, SO at 1% inclusion in the diet showed the potential to improve gas production kinetics, nutrient degradability, and the ruminal fermentation profile, with a more significant reduction in ruminal CH4 production suggesting that SO at 1% could be included in the ruminant diet to reduce their carbon footprint and increase the production performance.

The effect of Phyllanthus emblica (Amla) fruit supplementation on the rumen microbiota and its correlation with rumen fermentation in dairy cows

Introduction

Medicinal plants, rich in phytochemicals like phenolic acids, flavonoids, and tannins, offer potential benefits in enhancing productivity, quality, and animal health. Amla fruit (Phyllanthus emblica) is one such plant with promising attributes. This study aimed to investigate the impact of fresh Amla fruit (FAF) supplementation on ruminal microbial composition and its correlation with rumen fermentation in lactating dairy cows.

Methods

The study employed a repeated crossover design involving eight ruminally cannulated mid-lactation Holstein dairy cows. Animals received varying levels of fresh Amla fruit supplementation (0, 200, 400, and 600 g/d).

Results

When 400 g/d of FAF was added to the diet, there was a significant increase in the relative abundance of Firmicutes (p = 0.02). However, at 200 g/d, the relative abundance of ruminal Bacteroidota was higher than the 0 and 400 g/d FAF supplementation (p < 0.01). LEfSe analysis identified distinct taxa, such as Clostridia vadinBB60 in the 200 g/d group, Oscillospiraceae in the 400 g/d group, and Elusimicrobium in the 600 g/d group. Notably, the random forest species abundance statistics identified Oscillospiraceae V9D2013 as a biomarker related to milk yield. Oscillospiraceae, Bacilli RF39, norank_f Prevotellaceae, and Bifidobacterium were positively correlated with ruminal total VFA and molar proportion of propionate, while Rikenellaceae RC9 gut group and Clostridia vadinBB60 were negatively correlated.

Discussion

FAF supplementation affects the abundance of beneficial microbes in a dose-dependent manner, which can improve milk yield, efficiency, rumen health, desirable fatty acids, and animal health.

New biochemical pathways for forming short-chain fatty acids during fermentation in rumen bacteria

Short-chain fatty acids (SCFA) are essential to cattle as a source of energy and for other roles in metabolism. These molecules are formed during fermentation by microbes in the rumen, but even after decades of study, the biochemical pathways responsible for forming them are not always clear. Here we review recent advances in this area and their importance for improving animal productivity. Studies of bacterial genomes have pointed to unusual biochemical pathways in rumen organisms. One study found that 8% of rumen organisms forming acetate, a major SCFA, had genes for a pathway previously unknown in bacteria. The existence of this pathway was subsequently confirmed biochemically in propionibacteria. The pathway was shown to involve 2 enzymes that convert acetyl-coenzyme A to acetate. Similar studies have revealed new enzymatic steps for forming propionate and butyrate, other major SCFA. These new steps and pathways are significant for controlling fermentation. With more precise control over SCFA, cows can be fed more precisely and potentially reach higher productivity.

Improving Human Diets and Welfare through Using Herbivore-Based Foods: 2. Environmental Consequences and Mitigations

Animal-sourced foods are important for human nutrition and health, but they can have a negative impact on the environment. These impacts can result in land use tensions associated with population growth and the loss of native forests and wetlands during agricultural expansion. Increased greenhouse gas emissions, and high water use but poor water quality outcomes can also be associated. Life cycle analysis from cradle-to-distribution has shown that novel plant-based meat alternatives can have an environmental footprint lower than that of beef finished in feedlots, but higher than for beef raised on well-managed grazed pastures. However, several technologies and practices can be used to mitigate impacts. These include ensuring that grazing occurs when feed quality is high, the use of dietary additives, breeding of animals with higher growth rates and increased fecundity, rumen microbial manipulations through the use of vaccines, soil management to reduce nitrous oxide emission, management systems to improve carbon sequestration, improved nutrient use efficacy throughout the food chain, incorporating maize silage along with grasslands, use of cover crops, low-emission composting barns, covered manure storages, and direct injection of animal slurry into soil. The technologies and systems that help mitigate or actually provide solutions to the environmental impact are under constant refinement to enable ever-more efficient production systems to allow for the provision of animal-sourced foods to an ever-increasing population.

Synthesis, characterization, and inhibition effects of a novel eugenol derivative bearing pyrrole functionalities on the corrosion of mild steel in a HCl acid solution

Semi-synthetic modifications of natural products have yielded numerous anti-cancer drugs, antimicrobials, and corrosion inhibitors. In this study, eugenol, a natural product, was synthetically modified to generate a novel heterocyclic compound: pyrrole, which forms crystals. The latter is the outcome of the condensation reaction between eugenol hydrazide and 2,5-hexanedione, conducted under reflux ethanol conditions, without a catalyst, achieving a 96% yield. This compound structure was characterized through spectroscopic methods, such as NMR and FTIR, and validated par the crystal's X-ray diffraction analysis. According to the findings of the electrochemical study, pyrrole demonstrated effective inhibition against the carbon steel's corrosion in a 1 M HCl acid solution.

Effects of dietary basil (Ocimum basilicum) supplementation on reproductive hormones, semen parameters, and testicular development in Zandi male lambs

This study investigated the potential impact of feeding whole plant basil on sperm quality and the concentration of certain reproductive hormones in male lambs. A total of 18 Zandi male lambs with an initial weight of 28.8 ± 2.03 kg were included in a completely randomized design with three treatments and six repetitions. The experimental treatments included: 1) control (basal diet without basil), 2) diet containing 12.5 % basil, and 3) diet containing 25 % basil. The results showed that feeding basil to male lambs significantly increased testosterone concentration and decreased blood cortisol levels (P < 0.05). Additionally, feeding high levels of basil significantly improved sperm concentration, motility, and viability in the experimental samples, while reducing the level of complete abnormalities and malondialdehyde concentration (P < 0.05). The findings suggest that dietary supplementation of 25 % whole plant basil could be a useful strategy to improve sperm quality and increase testosterone secretion while reducing cortisol levels in male lambs.

A Review of Potential Feed Additives Intended for Carbon Footprint Reduction through Methane Abatement in Dairy Cattle

Eight rumen additives were chosen for an enteric methane-mitigating comparison study including garlic oil (GO), nitrate, Ascophyllum nodosum (AN), Asparagopsis (ASP), Lactobacillus plantarum (LAB), chitosan (CHI), essential oils (EOs) and 3-nitrooxypropanol (3-NOP). Dose-dependent analysis was carried out on selected feed additives using a meta-analysis approach to determine effectiveness in live subjects or potential efficacy in live animal trials with particular attention given to enteric gas, volatile fatty acid concentrations, and rumen microbial counts. All meta-analysis involving additives GO, nitrates, LAB, CHI, EOs, and 3-NOP revealed a reduction in methane production, while individual studies for AN and ASP displayed ruminal bacterial community improvement and a reduction in enteric CH4. Rumen protozoal depression was observed with GO and AN supplementation as well as an increase in propionate production with GO, LAB, ASP, CHI, and 3-NOP rumen fluid inoculation. GO, AN, ASP, and LAB demonstrated mechanisms in vitro as feed additives to improve rumen function and act as enteric methane mitigators. Enzyme inhibitor 3-NOP displays the greatest in vivo CH4 mitigating capabilities compared to essential oil commercial products. Furthermore, this meta-analysis study revealed that in vitro studies in general displayed a greater level of methane mitigation with these compounds than was seen in vivo, emphasising the importance of in vivo trials for final verification of use. While in vitro gas production systems predict in vivo methane production and fermentation trends with reasonable accuracy, it is necessary to confirm feed additive rumen influence in vivo before practical application.

Effect of a blend of cinnamaldehyde, eugenol, and Capsicum oleoresin on methane emission and lactation performance of Holstein-Friesian dairy cows

This study aimed to investigate the effect of administering a standardized blend of cinnamaldehyde, eugenol, and Capsicum oleoresin (CEC) to lactating dairy cattle for 84 d (i.e., 12 wk) on enteric CH4 emission, feed intake, milk yield and composition, and body weight. The experiment involved 56 Holstein-Friesian dairy cows (145 ± 31.1 d in milk at the start of the trial; mean ± standard deviation) in a randomized complete block design. Cows were blocked in pairs according to parity, lactation stage, and current milk yield, and randomly allocated to 1 of the 2 dietary treatments: a diet including 54.5 mg of CEC/kg of DM or a control diet without CEC. Diets were provided as partial mixed rations in feed bins, which automatically recorded individual feed intake. Additional concentrate was fed in the GreenFeed system that was used to measure emissions of CO2, CH4, and H2. Feeding CEC decreased CH4 yield (g/kg DMI) by on average 3.4% over the complete 12-wk period and by on average 3.9% from 6 wk after the start of supplementation onward. Feeding CEC simultaneously increased feed intake and body weight, and tended to increase milk protein content, whereas no negative responses were observed. These results must be further investigated and confirmed in longer-term in vivo experiments.

Effect of rice bran extract on in vitro rumen fermentation and methane production

This study was done to investigate which components of rice bran (RB) are involved in the inhibition of methanogenesis by fractionating the rice bran and adding it to a rumen in vitro culture system. The RB extract obtained using ethanol and water was screened in an in vitro fermentation system. The experimental treatment conditions were as follows: a control group containing a substrate without supplements; substrates with 0.06 g of RB; 0.6 mL of ethanol; 0.6 mL of distilled water (DW); 0.6 mL of ethanol-soluble fraction (ESF); 0.06 g of ethanol-insoluble rice bran (EIRB); 0.6 mL of water-soluble fraction (WSF); and 0.06 g of water-insoluble rice bran (WIRB). Based on the result of the analysis, the addition of ESF significantly decreased CH4 and CH4 /g dry matter digested, methanogen population (p < 0.05), while gas and dry matter digestibility (DMD) were comparable with the control group. Total short-chain fatty acid (SCFA), and proportion of propionate were reduced, and the proportion of butyrate was increased by the addition of ethanol and ESF (p < 0.05). This result suggests that the supplementation of 10% ESF can substantially reduce methane production in vitro without a negative effect on substrate digestibility.

Effect of residual methane emission on physiological characteristics and carcass performance in Japanese Black cattle

This study investigated the physiological characteristics and carcass performance associated with residual methane emissions (RME), and the effects of bull differences on CH4-related traits in Japanese Black cattle. Enteric methane (CH4) emissions from 156 Japanese Black cattle (111 heifers and 45 steers) were measured during early fattening using the sniffer method. Various physiological parameters were investigated to clarify the physiological traits between the high, middle, and low RME groups. CH4-related traits were examined to determine whether bull differences affected progeny CH4 emissions. Ruminal butyrate and NH3 concentrations were significantly higher in the high-RME group than in the low-RME group, whereas the propionate content was significantly higher in the low-RME group. Blood urea nitrogen, β-hydroxybutyric acid, and insulin concentrations were significantly higher, and blood amino acids were lower in the high-RME group than in the other groups. No significant differences were observed in the carcass traits and beef fat composition between RME groups. CH4-related traits were significantly different among bull herds. Our results show that CH4-related traits are heritable, wherein bull differences affect progeny CH4 production capability, and that the above-mentioned rumen fermentations and blood metabolites could be used to evaluate enteric methanogenesis in Japanese Black cattle.

Fennel seeds dietary inclusion as a sustainable approach to reduce methane production and improve nutrient utilization and ruminal fermentation

Ruminants are considered a major producer of methane (CH4 ). Therefore, the present study aimed to determine the ability of dry fennel seeds to affect in vitro gas production and fermentation. Fennel seeds were included at 0% (Control), 0.5%, 1%, 1.5%, and 2% DM of a diet containing per kg DM: 500 g concentrate feed mixture, 400 g berseem hay, and 100 g of rice straw. The incubations lasted 48 h. Fennel seeds increased (P < 0.001) the asymptotic gas production and decreased its rate, while decreasing the production and proportion of CH4 (P < 0.05) and increased its rate. Moreover, fennel seed increased DM and neutral detergent fiber (P < 0.01) degradability, and increased total production of short-chain fatty acids, acetate, and propionate (P < 0.05). Compared to the control, fennel seeds increased (P < 0.01) metabolizable energy, partitioning factor, and microbial crude protein production. Overall, fennel seeds can be included up to 2% DM in ruminant diets as an environmentally friendly product in animal farming due to its ability to improve feed utilization, ruminal fermentation and while reducing CH4 production.

Methane Emission, Carbon Footprint and Productivity of Specialized Dairy Cows Supplemented with Bitter Cassava (Manihot esculenta Crantz)

The objective of this research was to determine the effect of cassava (Manihot esculenta Crantz) supplementation on enteric methane (CH4) emissions, carbon footprint, and production parameters in dairy cows. Daily concentrate supply for Jersey and Jersey * Holstein breeds was evaluated in four treatments (T): T1: 100% commercial concentrate; T2: 70% concentrate + 30% cassava leaves; T3: 70% concentrate + 30% cassava roots; and T4: 70% concentrate + 15% cassava leaves + 15% cassava root chips. Measurements of CH4 emissions were performed using the polytunnel technique. Average daily dry matter intake ranged from 7.8 to 8.5 kg dry matter (DM). Cassava leaves were characterized by a high crude protein (CP) content (171 g CP/kg DM), with 5 times more neutral detergent fiber (NDF) content than cassava root (587 vs. 108 g NDF/kg DM). Average enteric CH4 emissions per animal ranged from 194 to 234 g/d (p > 0.05). The carbon footprint was reduced by replacing 30% of the concentrate with cassava leaves and/or roots. Energy-corrected milk production was 1.15 times higher in Jersey * Holstein animals than Jersey cows (47 vs. 55 kg). Therefore, supplementation with cassava leaves and/or roots is a nutritionally and environmentally sustainable strategy.

Multiple bHLH/MYB-based protein complexes regulate proanthocyanidin biosynthesis in the herbage of Lotus spp

MAIN CONCLUSION

The complexes involving MYBPA2, TT2b, and TT8 proteins are the critical regulators of ANR and LAR genes to promote the biosynthesis of proanthocyanidins in the leaves of Lotus spp. The environmental impact and health of ruminants fed with forage legumes depend on the herbage's concentration and structure of proanthocyanidins (PAs). Unfortunately, the primary forage legumes (alfalfa and clover) do not contain substantial levels of PAs. No significant progress has been made to induce PAs to agronomically valuable levels in their edible organs by biotechnological approaches thus far. Building this trait requires a profound knowledge of PA regulators and their interplay in species naturally committed to accumulating these metabolites in the target organs. Against this background, we compared the shoot transcriptomes of two inter-fertile Lotus species, namely Lotus tenuis and Lotus corniculatus, polymorphic for this trait, to search for differentially expressed MYB and bHLH genes. We then tested the expression of the above-reported regulators in L. tenuis x L. corniculatus interspecific hybrids, several Lotus spp., and different L. corniculatus organs with contrasting PA levels. We identified a novel MYB activator and MYB-bHLH-based complexes that, when expressed in Nicotiana benthamiana, trans-activated the promoters of L. corniculatus anthocyanidin reductase and leucoanthocyanidin reductase 1 genes. The last are the two critical structural genes for the biosynthesis of PAs in Lotus spp. Competition between MYB activators for the transactivation of these promoters also emerged. Overall, by employing Lotus as a model genus, we refined the transcriptional network underlying PA biosynthesis in the herbage of legumes. These findings are crucial to engineering this trait in pasture legumes.

Reduction of methane and nitrogen emission and improvement of feed efficiency, rumen fermentation, and milk production through strategic supplementation of eucalyptus (Eucalyptus citriodora) leaf meal in the diet of lactating buffalo (Bubalus bubalis)

Buffalo plays a compelling role in reducing malnutrition and ensuring food to the people of Asian countries by its major contribution to milk and meat pool of the livestock agriculture farming system in the region. As Asia is the home for more than 90% of world buffalo population, they are also one of the largest emitters of greenhouse gasses. Eucalyptus (Eucalyptus sp.) leaves are rich sources of naturally occurring essential oils and phenolic compounds, which could modulate rumen fermentation through mitigation of methanogenesis and nitrogen excretion along with stimulation of immune system and production performances of animals. Therefore, the present study investigated the impact of dietary inclusion of eucalyptus (Eucalyptus citriodora) leaf meal (ELM) on voluntary feed intake, rumen functions, methane emission, nutrient utilization, milk yield and fatty acids profile, and immune response in lactating buffalo (Bubalus bubalis). An in vitro experiment conducted with graded dose (10-40 g/kg) inclusion of ELM into the total mixed ration to select ideal level for feeding to lactating buffaloes, an improvement (P < 0.05) in feed degradability (IVDMD), microbial biomass and ruminal volatile fatty acids concentration with reduced (P < 0.05) methane and ammonia-N production were evidenced when ELM was added at 10-20 g/kg DM, beyond which negative effects on rumen fermentation were pronounced. An in vivo experimentation was conducted with sixteen Murrah (Bubalus bubalis) buffaloes of mean live weight, 544.23 ± 10.02 kg; parity, 2-4 at initial stage (~60 days) of lactation with average milk yield of 11.43 ± 1.32 kg and were divided into two groups (CON, ELM) of eight each in a completely randomized design. All the animals were kept individually on wheat straw-based diet with required quantity of concentrate mixture and green fodder. The control group buffaloes were fed a total mixed ration; however, the treatment group (ELM) was supplemented with 10 g/kg DM diet of dry grounded eucalyptus (Eucalyptus citriodora) leaves by mixing with the concentrate mixture. The feeding experiment was conducted for 120 days, including 15 days for adaptation to the experimental diets and 105 days for data recording. The nutrient digestibility (DM, OM, CP, and EE) was improved (P < 0.05) without affecting feed intake (P > 0.05) and fiber digestibility (NDF and ADF) in ELM supplemented buffaloes. Increased (P < 0.05) milk production and rumenic acid concentration (cis 9 trans 11 C18:2 CLA) were demonstrated with comparable (P > 0.05) milk composition and major fatty acids profile of milk in the supplemented buffaloes. Dietary inclusion of ELM reduced (P < 0.05) enteric methane production and fecal excretion of nitrogen. The health status of buffaloes fed ELM improved throughout the experimental period was improved by enhancing cell mediated (P = 0.09) and humoral (P < 0.01) immune responses without affecting (P > 0.05) major blood metabolites. The study described feeding ELM at 10 g/kg diet to lactating Murrah buffaloes as a natural source of phenols and essential oils to increase milk production and CLA content, reduce methane and nitrogen emissions, and improve health status. Thus, feeding of ELM could be beneficial for climate smart buffalo production system for enhancing milk production with lesser impact on environment.

Methane mitigation in ruminants with structural analogues and other chemical compounds targeting archaeal methanogenesis pathways

Ruminants are responsible for enteric methane production contributing significantly to the anthropogenic greenhouse gases in the atmosphere. Moreover, dietary energy is lost as methane gas without being available for animal use. Therefore, many mitigation strategies aiming at interventions at animals, diet, and microbiota have been explored by researchers. Specific chemical analogues targeting the enzymes of the methanogenic pathway appear to be more effective in specifically inhibiting the growth of methane-producing archaea without hampering another microbiome, particularly, cellulolytic microbiota. The targets of methanogenesis reactions that have been mainly investigated in ruminal fluid include methyl coenzyme M reductase (halogenated sulfonate and nitrooxy compounds), corrinoid enzymes (halogenated aliphatic compounds), formate dehydrogenase (nitro compounds, e.g., nitroethane and 2-nitroethanol), and deazaflavin (F420) (pterin and statin compounds). Many other potential metabolic reaction targets in methanogenic archaea have not been evaluated properly. The analogues are specifically effective inhibitors of methanogens, but their efficacy to lower methanogenesis over time reduces due to the metabolism of the compounds by other microbiota or the development of resistance mechanisms by methanogens. In this short review, methanogen populations inhabited in the rumen, methanogenesis pathways and methane analogues, and other chemical compounds specifically targeting the metabolic reactions in the pathways and methane production in ruminants have been discussed. Although many methane inhibitors have been evaluated in lowering methane emission in ruminants, advancement in unravelling the molecular mechanisms of specific methane inhibitors targeting the metabolic pathways in methanogens is very limited.

Methane reduction by quercetin, tannic and salicylic acids: influence of molecular structures on methane formation and fermentation in vitro

Plant secondary metabolites (PSMs) can potentially reduce ruminal methane formation. However, related to differences in their molecular structures, it is not yet clear what causes an anti-methanogenic effect. In an in vitro system simulating rumen fermentation, we investigated the impact of eight compounds with distinct chemical characteristics (gallic and salicylic acids, tannic acid, catechin, epicatechin, quercetin, rutin, and salicin) when added to a basal feed (maize silage) at a concentration of 12% of the feed dry matter. After 48 h of incubation in buffered rumen fluid, methane production was significantly lowered by quercetin (43%), tannic acid (39%) and salicylic acid (34%) compared to the control (maize silage alone) and without changes in total volatile fatty acid production during fermentation. No other PSM reduced methane formation as compared to control but induced significant differences on total volatile fatty acid production. The observed differences were related to lipophilicity, the presence of double bond and carbonyl group, sugar moieties, and polymerization of the compounds. Our results indicate the importance of distinct molecular structures of PSMs and chemical characteristics for methane lowering properties and volatile fatty acid formation. Further systematic screening studies to establish the structure-function relationship between PSMs and methane reduction are warranted.

Modulation of feed digestibility, nitrogen metabolism, energy utilisation and serum biochemical indices by dietary Ligularia virgaurea supplementation in Tibetan sheep

Ligularia virgaurea is the most widely functional native herbage in the alpine meadow pastures of the Qinghai-Tibet Plateau (QTP) and has multiple pharmacological and biological activities. The effect of L. virgaurea as a dietary component on the digestion and metabolism of sheep was evaluated by conducting feeding trials in metabolic cages. Thirty-two Tibetan yearling rams (29 ± 1.56 kg BW) were randomly allotted to four groups included in a completely randomised design with eight animals per treatment. Sheep were fed a basal diet (freshly native pasture) without the addition of L. virgaurea (control) or with the addition of L. virgaurea (100, 200, or 300 mg/kg BW per day) for 45 days. Addition of L. virgaurea to the diet of Tibetan sheep was found to influence the average daily gain (quadratic [Q], P < 0.001), feed conversion ratio (Q, P = 0.002), CH4 emissions (linear [L], P = 0.029), DM (Q, P = 0.012), neutral detergent fibre (Q, P = 0.017), acid detergent fibre (ADF) (Q, P = 0.027), and ether extract (EE) intake (Q, P = 0.026). Apparently, different levels of L. virgaurea affected the digestibility coefficients of DM, ADF, and EE (L, P > 0.05; Q, P < 0.05). The nitrogen (N) intake (Q, P = 0.001), retained nitrogen (Q, P < 0.001), and N utilisation efficiency (L, P > 0.05; Q, P ≤ 0.001) were also affected by the dietary inclusion of L. virgaurea. Effects of L. virgaurea feeding were also witnessed on methane energy (CH4-E) (L, P = 0.029), gross energy (GE) (Q, P = 0.013), digestible energy (DE) (Q, P = 0.015), and metabolisable energy (ME) intake (Q, P = 0.015). Energy utilisation efficiency expressed as a proportion of GE intake (DE/GE intake, ME/GE intake, ME/DE intake, FE/GE intake, and CH4-E/GE intake) manifested quadratic changes (P < 0.05) with the increase in the L. virgaurea supplementation level. The addition of L. virgaurea increased the activity of superoxide dismutase (Q, P = 0.026) and glutathione peroxidase activity (Q, P = 0.039) in the serum. Overall, the greatest improvement of feed digestibility, N retention, energy utilisation, and antioxidant capacity of Tibetan sheep was yielded by the inclusion of 200 mg/kg BW per day of L. virgaurea. Therefore, the addition of an appropriate amount of L. virgaurea to the diet of Tibetan sheep is safe and natural, and may enhance the sustainability of small ruminant production systems in QTP areas.

Enteric methane emissions in grazing dairy systems

Approximately 80% of agricultural CH₄ comes from livestock systems, with 90% of that derived from enteric CH₄ production by ruminants. Grazing systems are used worldwide to feed dairy cattle. Although quantifying enteric CH₄ emissions in grazing systems has unique challenges, emerging technologies have made gaseous data collection more feasible and less laborious. Nevertheless, robust data sets on enteric CH₄ emissions under various grazing conditions, as well as effective and economic strategies to mitigate CH₄ emissions in grazing dairy cows, are still in high demand because data collection, feeding management, and milk market regulations (e.g., organic certification, grassfed) impose more challenges to grazing than confinement dairy systems. This review will cover management strategies to mitigate enteric CH₄ emissions and applicability to pastoral dairy systems. The effects of enteric CH₄ in the broader context of whole-system assessments will be discussed, which are key to assess the overall environmental impact of grazing dairies.

Effect of supplementation of roasted oilseeds and phytochemical-rich herbages on nutrient utilization, methane emission, and growth performance in finisher lambs

Ruminal methanogenesis is a major contributor to global environmental pollution in the agriculture sector. Dietary intervention modestly abates enteric methane emissions in ruminants. Therefore, the present experiment was conducted to evaluate the combined effect of dietary oilseeds and phytochemical-rich herbages on enteric methane emission, growth performance, and nutrient utilization in lambs. Forty-eight finisher Malpura lambs were divided into 4 groups (RSZ, RSP, RSLZ, and RSLP) of 12 each in a factorial design. Lambs were fed ad libitum concentrate formulated with roasted soybean (RS) or roasted soybean plus linseed (RSL) along with Ziziphus nummularia (Z) or Prosopis cineraria (P) leaves as roughage sources. Variation in the source of roughage significantly affected feed intake, and it was higher (P < 0.05) in lambs fed Prosopis cineraria leaves (RSP and RSLP). The average daily gain was improved (P < 0.05) by 28.6 and 25.0% in lambs fed Prosopis cineraria, i.e., RSP and RSLP respectively, than those fed Ziziphus nummularia leaves irrespective of concentrate diets. Overall, microbial nitrogen synthesis (MNS) was higher (P < 0.05) in lambs fed roasted soybean (RS) than roasted soybean plus linseed (RSL); however, combination of Prosopis cineraria with both the concentrate diets increased MNS, than the combination of roasted oilseeds and Ziziphus nummularia. No significant interaction was observed in the concentration and proportion of volatile fatty acids by feeding combination of roasted oilseed and tree leaves; however, the proportion of acetic and propionic acid was higher (P < 0.05) in the RSL group compared to RS. Methane emission per kg dry matter intake was reduced (P < 0.05) by feeding Prosopis cineraria leaves regardless of concentrate mixture. As a result, the loss of metabolizable energy through methane emission was lowered by 0.7 and 4.6% when Prosopis cineraria leaves were combined with roasted soybean (RSP) and roasted soybean plus linseed (RSLP), respectively. From the present findings, it can be concluded that combination of Prosopis cineraria leaves either with roasted soybean or roasted soybean plus linseed reduced enteric methane emissions more effectively than Ziziphus nummularia leaves, and the energy saved was transformed into higher body weight gain and improved feed conversion ratio.

Screening macroalgae for mitigation of enteric methane in vitro

This study investigated the effects of 67 species of macroalgae on methanogenesis and rumen fermentation in vitro. Specimens were analyzed for their effect on ruminal fermentation and microbial community profiles. Incubations were carried out in an automated gas production system for 24-h and macroalgae were tested at 2% (feed dry matter basis) inclusion rate. Methane yield was decreased 99% by Asparagopsis taxiformis (AT) when compared with the control. Colpomenia peregrina also decreased methane yield 14% compared with control; no other species influenced methane yield. Total gas production was decreased 14 and 10% by AT and Sargassum horneri compared with control, respectively. Total volatile fatty acid (VFA) concentration was decreased between 5 and 8% by 3 macroalgae, whereas AT reduced it by 10%. Molar proportion of acetate was decreased 9% by AT, along with an increase in propionate by 14%. Asparagopsis taxiformis also increased butyrate and valerate molar proportions by 7 and 24%, respectively, whereas 3 macroalgae species decreased molar proportion of butyrate 3 to 5%. Vertebrata lanosa increased ammonia concentration, whereas 3 other species decreased it. Inclusion of AT decreased relative abundance of Prevotella, Bacteroidales, Firmicutes and Methanobacteriaceae, whereas Clostridium, Anaerovibrio and Methanobrevibacter were increased. Specific gene activities for Methanosphaera stadtmane and Methanobrevibacter ruminantium were decreased by AT inclusion. In this in vitro study, Asparagopsis taxiformis was most effective in decreasing methane concentration and yield, but also decreased total gas production and VFA concentration which indicates overall inhibition of ruminal fermentation. No other macroalgae were identified as potential mitigants of enteric methane.

Modulation of milking performance, methane emissions, and rumen microbiome on dairy cows by dietary supplementation of a blend of essential oils

Cattle represent a high contribution of the livestock's greenhouse gas emissions, mainly in the form of methane. Essential oils are a group of plant secondary metabolites obtained from volatile fractions of plants that have been shown to exert changes in the rumen fermentation and may alter feed efficiency and to reduce methane production. The objective of this study was to investigate the effect on rumen microbial population, CH₄ emissions and milking performance of a mixture of essential oils (Agolin Ruminant, Switzerland) incorporated daily in the ration of dairy cattle. Forty Holstein cows (644 ± 63.5 kg of BW producing 41.2 ± 6.44 kg/d of milk with 190 ± 28.3 DIM) were divided into two treatments (n = 20) for 13 wk and housed in a single pen equipped with electronic feeding gates to control access to feed and monitor individual DM intake (DMI) on a daily basis. Treatments consisted of no supplementation (Control) or supplementation of 1 g/d of a blend of essential oils (BEOs) fed in the TMR. Individual milk production was recorded using electronic milk meters on a daily basis. Methane emissions were recorded using sniffers at the exit of the milking parlour. At day 64 of the study, a sample of rumen fluid was collected from 12 cows per treatment after the morning feeding using a stomach tube. There were no differences in DMI, milk yield, or milk composition between the two treatments. However, cows on BEO exhaled less CH₄ (444 ± 12.5 l/d) than cows on Control (479 ± 12.5 l/d), and exhaled less (P < 0.05) CH₄/kg of DM consumed (17.6 vs 20.1 ± 0.53 l/kg, respectively) from the first week of study, with no interaction with time, which suggests a fast action of BEO of CH₄ emissions. Rumen relative abundance of Entodonium increased, and those of Fusobacteria, Chytridiomycota, Epidinium, and Mogibacterium decreased in BEO compared with Control cows. Supplementing 1 g/d of BEO reduces CH₄ emissions on absolute terms (l/d) and diminishes the amount of CH₄ produced by unit of DM consumed by cows relatively soon after the first supplementation, and the effect is sustained over time without impacting intake or milking performance.

Effects of Processing Methods and Inclusion Levels of Dried Garlic on In Vitro Fermentation and Methane Production in a Corn Silage-Based Substrate

Garlic (Allium sativum) contains secondary compounds that are known to modify rumen fermentation parameters and decrease methane (CH4) emissions. The objective was to evaluate the effects of increasing the inclusion levels and processing methods of garlic on in vitro fermentation and CH4 production. Treatments were arranged in a randomized complete block design with a 2 × 3 × 2 + 1 factorial arrangement, where the main factors were the initial condition of garlic (intact or smashed), drying process (freeze-dried, oven-dried, or autoclaved), and garlic proportion in the diet (2.5 and 5%) and one control (without garlic supplementation). Incubations were conducted using corn silage and cotton-gin trash (80:20, respectively) as basal substrates on three different days. Final pH, the concentration of volatile fatty acids (VFA) and ammonia nitrogen (NH3-N), in vitro organic matter digestibility (IVOMD), total gas production, and CH4 concentration were determined after 24 h. Initial garlic condition or drying processing neither modify (p > 0.05) the in vitro fermentation nor the CH4 production. However, increasing garlic inclusion linearly increased (p < 0.05) IVOMD, the concentration of the total VFA, and the proportion of propionate. Also, the concentration of NH3-N and the proportion of acetate increased quadratically (p < 0.05) with greater garlic inclusions. Finally, garlic inclusion did not affect (p > 0.05) gas and CH4 production. In conclusion, increasing garlic levels, but not the processing methods, improved in vitro fermentation but did not modify CH4 emissions under in vitro conditions.

Effect of Tea Saponins on Rumen Microbiota and Rumen Function in Qinchuan Beef Cattle

Antibiotics can promote livestock growth but have side effects, so the search for safe and effective alternatives to antibiotics is urgent. This study aimed to evaluate the effect of supplementing cattle feed with tea saponins on ruminal bacteria and fungi. Sixteen Qinchuan beef cattle with a live body weight of 250 ± 10 kg were divided into four groups (four animals in each group) using a completely randomized experimental design. Four different levels of tea saponins were provided to the Qinchuan cattle as treatments, including 0 g/cattle per day control, CON), 10 g/cattle per day (low-level, LT), 20 g/cattle per day (medium-level, MT) and 30 g/cattle per day (high-level, HT). The pre-feeding period was 10 days and the official period was 80 days in this experiment. After 90 days of feeding, the rumen fluid from sixteen Qinchuan beef cattle was collected using an oral stomach tube for evaluating changes in ruminal microbiota and rumen fermentation parameters. Results indicate that the total VFAs and proportions of propionate in the LT group was significantly higher than that in the CON and HT groups (p < 0.05). For ruminal bacteria, results indicate that the Chao1 index of the MT group was significantly lower than the CON and HT groups (p < 0.05). The phyla Bacteroidetes and Firmicutes were found to be the most abundant in all treatment groups, with the LT group having significantly increased relative abundances of Proteobacteria, Actinobacteria and Ascomycota at the phylum level (p < 0.05). The relative abundance of Bacteroides was found to be relatively lower in the LT, MT and HT treatment groups compared with the CON treatment group at the genus level (p < 0.05). For ruminal fungi, the LT treatment group was found to have higher relative abundances of Saccharomyces and Aspergillus, and lower relative abundances of Succiniclasticum and Bacteroides at the at the phylum level (p < 0.05). Compared with the CON treatment group, a significant increase in the relative abundance of Saccharomyces and Aspergillus were observed in the LT treatment group at the genus level (p < 0.05). PICRUSt analyses identified pathways associated with Xenobiotic biodegradation and metabolism and glycolysisIII to be significantly enriched in the LT and HT treatment groups (p < 0.05). These findings could provide insights on how tea saponins may influence ruminal bacteria and fungi, providing a theoretical basis for replacing antibiotics with tea saponins for promoting growth in cattle.

Ruminal fermentation and methane production in vitro, milk production, nutrient utilization, blood profile, and immune responses of lactating goats fed polyphenolic and saponin-rich plant extracts

This study was conducted to evaluate the effect of a composite plant extract (CPE) rich in polyphenolics and saponins from seeds of Dolichos biflorus (horse gram), root of Asparagus racemosus (shatavari), bark of Amoora rohituka (rohitaka), and peel of Punica granatum (pomegranate) on ruminal fermentation and methanogenesis in vitro, milk production, nutrient digestibility, immune response, and blood profiles in lactating Beetal goats fed CPE at 20 g/kg diet. Dose effect of CPE was assessed using different doses (0, 10, 20, 30, and 40 g/kg substrate) to find out an optimum dose for the in vivo study. The in vivo experiment lasted 70 days including a 10-day adaptation period. In the in vitro study, dry matter (DM) and fiber degradability increased linearly (P < 0.05) and methane production and ammonia concentration decreased linearly (P < 0.05) with increasing doses of CPE. Concentrations of total VFA and proportion of propionate increased (P < 0.001) linearly, whereas proportion of acetate and acetate to propionate ratio decreased with a linear effect. Dietary CPE increased milk yield (P = 0.017) and concentrations of protein and lactose (P = 0.045) by CPE, but concentrations of fat and solid not fat in milk were not affected (P > 0.10). Somatic cell counts in milk reduced (P = 0.045) in the CPE-fed goats. Apparent digestibility of DM (P = 0.037) increased significantly and NDF (P = 0.066) tended to increase due to supplementation of CPE. Blood glucose (P = 0.028) and albumin (P = 0.007) concentrations increased, while other liver-marker metabolites and enzyme activities and superoxide dismutase activity were not altered in goats due to feeding of CPE. Concentrations of total amino acids (P = 0.010), total essential amino acids (P = 0.012), and total ketogenic amino acids (P < 0.001) were greater in the CPE-fed goats than the control goats. Cell-mediated immune response improved due to CPE feeding. This study suggests that the CPE rich in both phenolics and saponins could improve ruminal fermentation, milk production, and nutrient utilization in lactating goats with better health status while decreasing methane emission.

Mulberry flavonoids modulate rumen bacteria to alter fermentation kinetics in water buffalo

Mulberry flavonoids can modulate the composition of rumen microbiota in ruminants to improve nutrient digestibility, owing to their strong biological activities. This study aimed to explore the effect of mulberry leaf flavonoids (MLF) on rumen bacteria, fermentation kinetics, and metagenomic functional profile in water buffalo. Forty buffaloes (4 ± 1 lactations) with almost same body weight (av. 600 ± 50 Kg) and days in milk (90 ± 20 d) were randomly allocated to four treatments having different levels of MLF: 0 g/d (control), 15 g/d (MLF15), 30 g/d (MLF30), and 45 g/d (MLF45) supplemented in a basal diet. After 35 days of supplementation, rumen contents were collected to determine rumen fermentation parameters. The 16S rRNA gene sequencing was performed to elucidate rumen bacteria composition. The obtained taxonomic data were analyzed to explore the rumen bacteriome and predict the associated gene functions and metabolic pathways. Results demonstrated a linear increase (p < 0.01) in rumen acetate, propionate, and total VFAs in the MLF45 group as compared to control. No effect of treatment was observed on rumen pH and butyrate contents. Acetate to propionate ratio in the MLF45 group linearly and quadratically decreased (p = 0.001) as compared to MLF15 and control groups. Similarly, MLF45 linearly increased (p < 0.05) the microbial protein (MCP) and NH₃-N as compared to other treatments. Treatment adversely affected (p < 0.01) almost all alpha diversity parameters of rumen bacteria except Simpson index. MLF promoted the abundance of Proteobacteria while reducing the relative abundances of Actinobacteria, Acidobacteria, Chloroflexi, and Patescibacteria. The MLF supplementation tended to substantially reduce (0.05 < p < 0.1) the abundance of Actinobacteria, and Patescibacteria while completely eliminating Acidobacteria (p = 0.029), Chloroflexi (p = 0.059), and Gemmatimonadetes (p = 0.03) indicating the negative effect of flavonoids on the growth of these bacteria. However, MLF45 tended to substantially increase (p = 0.07) the abundance (~21.5%) of Acetobacter. The MLF treatment exhibited negative effect on five genera by significantly reducing (Sphingomonas) or eliminating (Arthobactor, unclassified_c__Actinobacteria, norank_c__Subgroup_6, norank_o__Saccharimonadales, and Nocardioides) them from the rumen microbiota. Pearson correlation analysis revealed 3, 5 and 23 positive correlations of rumen bacteria with milk yield, rumen fermentation and serum antioxidant parameters, respectively. A positive correlation of MCP was observed with three bacterial genera (Acetobacter, Enterobacter, and Klebsiella). The relative abundance of Pseudobutyrivibrio and Empedobacter also showed a positive correlation with the ruminal acetate and propionate. The present study indicated 45 g/d as an appropriate dose of MLF which modulated rumen bacteria and its functional profile in water buffalo.

The Antimethanogenic Potentials of Plant Extracts: Their Yields and Phytochemical Compositions as Affected by Extractive Solvents

Plant phytochemicals are an important area of study in ruminant nutrition, primarily due to their antimethanogenic potentials. Plant extract yields, their bioactive compounds and antimethanogenic properties are largely dependent on the nature of the extractive solvents. This study evaluated the yields and phytochemical constituents of four plant extracts, as affected by the aqueous-methanolic (H2O-CH3OH) extraction and their antimethanogenic properties on the in vitro methane production. The plant extracts included Aloe vera, Jatropha curcas, Moringa oleifera, and Piper betle leaves with three levels of extractions (70, 85, and 100% CH3OH). The crude plant extract yields increased with the increasing amount of water. M. oleifera crude extracts yields (g/10 g) increased from 3.24 to 3.92, A. vera, (2.35 to 3.11) J. curcas (1.77 to 2.26), and P. betle (2.42 to 3.53). However, the identified and quantified metabolites showed differing degrees of solubility unique to their plant leaves in which they exist, while some of the metabolites were unaffected by the extraction solvents. The methane mitigating potentials of these extracts were evaluated as additives on Eragrostis curvula hay at a recommended rate of 50 mg kg−1 DM. The plant extracts exhibited antimethanogenic properties to various degrees, reducing (p < 0.05) in vitro methane production in the tested hay, A. vera, J. curcas, M. oleifera and P. betle reduced methane emission by 6.37−7.55%, 8.02−11.56%, 12.26−12.97, and 5.66−7.78 respectively compared to the control treatment. However, the antimethanogenic efficacy, gas production and organic matter digestibility of the plant extracts were unaffected by the extraction solvents. Metabolites, such as aloin A, aloin B and kaempferol (in A. vera), apigenin, catechin, epicatechin, kaempferol, tryptophan, procyanidins, vitexin-7-olate and isovitexin-7-olate (in J. curcas), alkaloid, kaempferol, quercetin, rutin and neochlorogenic acid (in M. oleifera) and apigenin-7,4′-diglucoside, 3-p-coumaroylquinic acid, rutin, 2-methoxy-4-vinylphenol, dihydrocaffeic acid, and dihydrocoumaric acid (in P. betle) exhibited a methane reducing potential and hence, additional studies may be conducted to test the methane reducing properties of the individual metabolites as well as their combined forms. Plant extracts could be more promising, and hence, further study is necessary to explore other extraction methods, as well as the encapsulation of extracts for the improved delivery of core materials to the target sites and to enhance methane reducing properties. Furthermore, the use of 70% aqueous extraction on M. oleifera leaf is recommended for practical use due to the reduced cost of extractive solvents, the lower cost and availability of Moringa plants in South Africa, especially in Gauteng Province. Furthermore, 70% aqueous-methanolic extractions of A. vera, J. curcas, and P. betle are recommended for practical use in regions where they exist in abundance and are cost effective.

Red seaweed extracts reduce methane production by altering rumen fermentation and microbial composition in vitro

A series of in vitro batch culture incubations were carried out to investigate changes in rumen fermentation characteristics, methane (CH4) production, and microbial composition in response to supplementation with five different red seaweed species (Amphiroa anceps, AANC; Asparagopsis taxiformis, ATAX; Chondracanthus tenellus, CTEN; Grateloupia elliptica, GELL; and Gracilaria parvispora, GPAR). Prior to the incubations, the total flavonoid and polyphenol content of the red seaweed extracts was quantified. The incubated substrate consisted of timothy hay and corn grain [60:40 dry matter (DM) basis]. Treatments were substrate mixtures without seaweed extract (CON) or substrate mixtures supplemented with 0.25 mg/mL of red seaweed extract. Samples were incubated for 6, 12, 24, 36, and 48 h. Each sample was incubated in triplicates in three separate runs. In vitro DM degradability, fermentation parameters (i.e., pH, volatile fatty acids, and ammonia nitrogen), total gas production, and CH4 production were analyzed for all time points. Microbial composition was analyzed using 16S rRNA amplicon sequencing after 24 h of incubation. The highest CH4 reduction (mL/g DM, mL/g digested DM, and % of total gas production) was observed in ATAX (51.3, 50.1, and 51.5%, respectively, compared to CON; P < 0.001) after 12 h of incubation. The other red seaweed extracts reduced the CH4 production (mL/g DM; P < 0.001) in the range of 4.6-35.0% compared to CON after 24 h of incubation. After 24 h of incubation, supplementation with red seaweed extracts tended to increase the molar proportion of propionate (P = 0.057) and decreased the acetate to propionate ratio (P = 0.033) compared to the CON. Abundances of the genus Methanobrevibacter and total methanogens were reduced (P = 0.050 and P = 0.016) by red seaweed extract supplementation. The linear discriminant analysis effect size (P < 0.05, LDA ≥ 2.0) showed that UG Succinivibrionaceae, Anaeroplasma, and UG Ruminococcaceae, which are associated with higher propionate production, starch degradation, and amylase activity were relatively more abundant in red seaweed extracts than in the CON. Our results suggest that supplementation with red seaweed extracts altered the microbiota, leading to the acceleration of propionate production and reduction in CH4 production.

Effect of supplemental malic acid on methane mitigation in paddy straw based complete diet for sustainable animal production in indigenous dairy cattle

A study was conducted to evaluate the effect of supplemental malic acid on mitigation of methane emission for dairy cattle by in vitro and in vivo methods. The in vitro finding was validated by in vivo feeding trial in indigenous dairy cattle. Ten dairy cattle with uniform milk production were selected and divided into two groups with five animals each and they were fed with and without supplementation of malic acid at 0.39% in 60% paddy straw and 40% concentrate mixture based complete diet. The malic acid at 0.39% was the minimum level which resulted in highly significant reduction of methane by 15.95% and methane (ml) per 100 mg of truly digested substrate by 15.69%, respectively than control in in vitro study. The methane emission per animal per day and per kg dry matter intake (DMI) was significantly decreased by 3.26% and 3.11%, respectively in malic acid supplemented group than control. The methane emission per kg milk production was significantly reduced by 5.43% in malic acid supplemented group than control. The total volatile fatty acid (TVFA) and propionic acid were significantly increased by 2.69% and 11.71%, respectively in malic acid supplemented group than control. It was concluded that the supplementation of malic acid at 0.39% of paddy straw based complete diet significantly reduced the methane emission per animal per day and per kg milk production than control in indigenous dairy cattle.

Garlic and Its Bioactive Compounds: Implications for Methane Emissions and Ruminant Nutrition

Methane (CH4) emission from enteric fermentation of ruminant livestock is a source of greenhouse gases (GHG) and has become a significant concern for global warming. Enteric methane emission is also associated with poor feed efficiency. Therefore, research has focused on identifying dietary mitigation strategies to decrease CH4 emissions from ruminants. In recent years, plant-derived bioactive compounds have been investigated for their potential to reduce CH4 emissions from ruminant livestock. The organosulphur compounds of garlic have been observed to decrease CH4 emission and increase propionate concentration in anaerobic fermentations (in vitro) and in the rumen (in vivo). However, the mode of action of CH4 reduction is not completely clear, and the response in vivo is inconsistent. It might be affected by variations in the concentration and effect of individual substances in garlic. The composition of the diet that is being fed to the animal may also contribute to these differences. This review provides a summary of the effect of garlic and its bioactive compounds on CH4 emissions by ruminants. Additionally, this review aims to provide insight into garlic and its bioactive compounds in terms of enteric CH4 mitigation efficacy, consistency in afficacy, possible mode of action, and safety deriving data from both in vivo and in vitro studies.

Condensed and Hydrolyzable Tannins for Reducing Methane and Nitrous Oxide Emissions in Dairy Manure-A Laboratory Incubation Study

The objectives of this study were to (1) examine the effects of plant condensed (CT) and hydrolyzable tannin (HT) extracts on CH4 and N2O emissions; (2) identify the reactions responsible for manure-derived GHG emissions, and (3) examine accompanying microbial community changes in fresh dairy manure. Five treatments were applied in triplicate to the freshly collected dairy manure, including 4% CT, 8% CT, 4% HT, 8% HT (V/V), and control (no tannin addition). Fresh dairy manure was placed into 710 mL glass incubation chambers. In vitro composted dairy manure samples were collected at 0, 24, 48, and 336 h after the start of incubation. Fluxes of N2O and CH4 were measured for 5-min/h for 14 d at a constant ambient incubation temperature of 39 °C. The addition of quebracho CT significantly decreased the CH4 flux rates compared to the tannin-free controls (215.9 mg/m2/h), with peaks of 75.6 and 89.6 mg/m2/h for 4 and 8% CT inclusion rates, respectively. Furthermore, CT significantly reduced cumulative CH4 emission by 68.2 and 57.3% at 4 and 8% CT addition, respectively. The HT treatments failed to affect CH4 reduction. However, both CT and HT reduced (p < 0.001) cumulative and flux rates of N2O emissions. The decrease in CH4 flux with CT was associated with a reduction in the abundance of Bacteroidetes and Proteobacteria.

Producing natural functional and low-carbon milk by regulating the diet of the cattle-The fatty acid associated rumen fermentation, biohydrogenation, and microorganism response

Conjugated linoleic acid (CLA) has drawn significant attention in the last two decades for its various potent beneficial effects on human health, such as anticarcinogenic and antidiabetic properties. CLA could be generally found in ruminant products, such as milk. The amount of CLA in ruminant products mainly depends on the diet of the animals. In general, the fat content in the ruminant diet is low, and dietary fat supplementation can be provided to improve rumen activity and the fatty acid (FA) profile of meat and milk. Especially, dietary 18-carbon polyunsaturated FA (C18 PUFA), the dominant fat source for ruminants, can modify the milk FA profile and other components by regulating the ruminal microbial ecosystem. In particular, it can improve the CLA in milk, intensify the competition for metabolic hydrogen for propionate producing pathways and decrease methane formation in the rumen. Therefore, lipid supplementation appears to be a promising strategy to naturally increase the additional nutritional value of milk and contribute to lower methane emissions. Meanwhile, it is equally important to reveal the effects of dietary fat supplementation on rumen fermentation, biohydrogenation (BH) process, feed digestion, and microorganisms. Moreover, several bacterial species and strains have been considered to be affected by C18 PUFA or being involved in the process of lipolysis, BH, CLA, or methane emissions. However, no review so far has thoroughly summarized the effects of C18 PUFA supplementation on milk CLA concentration and methane emission from dairy cows and meanwhile taken into consideration the processes such as the microorganisms, digestibility, rumen fermentation, and BH of dairy cattle. Therefore, this review aims to provide an overview of existing knowledge of how dietary fat affects rumen microbiota and several metabolic processes, such as fermentation and BH, and therefore contributes to functional and low-carbon milk production.

Dose–Response Effects of Bamboo Leaves on Rumen Methane Production, Fermentation Characteristics, and Microbial Abundance In Vitro

Simple Summary

Due to economic, environmental, and nutritional considerations, mitigating enteric methane production from ruminants is an important issue. Nutritionists have recently shown that feeding livestock natural feed additives could ameliorate this problem, due to the antimicrobial activities of the biologically active components in the additives. Bamboo is widely distributed in Asia and is currently being used in construction and paper pulp production, which results in a significant amount of bamboo leaves as by-products. The present study investigated whether bamboo leaves feeding can decrease methane production in ruminants. Here we found that bamboo leaves supplementation in vitro caused a 12.7–34.2% reduction in methane production after 12 and 48 h. Further studies are needed to demonstrate the effect of bamboo leaves supplementation in vivo, to determine its potential for mitigating methane production from ruminants.

Abstract

Ruminants produce large amounts of methane as part of their normal digestive processes. Recently, feed additives were shown to inhibit the microorganisms that produce methane in the rumen, consequently reducing methane emissions. The objective of this study was to evaluate the dose–response effect of Phyllostachys nigra var. henonis (PHN) and Sasa borealis supplementation on in vitro rumen fermentation, methane, and carbon dioxide production, and the microbial population. An in vitro batch culture system was used, incubated without bamboo leaves (control) or with bamboo leaves (0.3, 0.6, and 0.9 g/L). After 48 h, total gas, methane, and carbon dioxide production decreased linearly with an increasing dose of bamboo leaves supplementation. The total volatile fatty acid, acetate, and acetate-to-propionate ratio were affected quadratically with increasing doses of bamboo leaves supplementation. In addition, propionate decreased linearly. Butyrate was increased linearly with increasing doses of PHN supplementation. The absolute values of total bacteria and methanogenic archaea decreased linearly and quadratically with an increasing dose of PHN treatment after 48 h. These results show that bamboo leaves supplementation can reduce methane production by directly affecting methanogenic archaea, depressing the metabolism of methanogenic microbes, or transforming the composition of the methanogenic community. These results need to be validated using in vivo feeding trials before implementation.

Effects of Dietary Inclusion of Sericea Lespedeza Hay on Feed Intake, Digestion, Nutrient Utilization, Growth Performance, and Ruminal Fermentation and Methane Emission of Alpine Doelings and Katahdin Ewe Lambs

Twenty-four Alpine doelings, initial 25.3 ± 0.55 kg body weight (BW) and 10.4 ± 0.11 mo of age, and 24 Katahdin ewe lambs, 28.3 ± 1.02 kg BW and 9.6 ± 0.04 mo of age, were used to determine effects of dietary inclusion of Sericea lespedeza (Lespedeza cuneata) hay on feed intake, digestion, growth performance, energy metabolism, and ruminal fermentation and methane emission. There were four periods, the first three 42 days in length and the fourth 47 days. Diets consumed ad libitum contained 75% coarsely ground hay with alfalfa (ALF), a 1:1 mixture of ALF and LES (ALF+LES), and LES (10.0% condensed tannins; CT). The intake of dry matter (DM) tended to be greater (p = 0.063) for Katahdin than for Alpine (4.14 vs. 3.84% BW; SEM = 0.110). The dry matter intake was similar among the diets (3.97, 4.10, and 3.89% BW for ALF, ALF+LES, and LES, respectively; SEM = 0.134). The digestion of organic matter (75.3, 69.3, and 65.5%; SEM = 0.86), neutral detergent fiber (61.7, 50.5, and 41.4%; SEM = 1.49), and nitrogen (78.8, 66.9, and 50.8% for ALF, ALF+LES, and LES, respectively; SEM = 0.92) decreased as the dietary concentration of lespedeza increased (p < 0.05). However, there was an interaction (p < 0.05) between the breed and diet in nitrogen digestion, with a greater value for goats vs. sheep with LES (54.4 vs. 47.3%; SEM = 1.30). The digested nitrogen intake decreased markedly with the increasing quantity of lespedeza (38.0, 27.5, and 15.7 g/day for ALF, ALF+LES, and LES, respectively; SEM = 1.26). The average daily gain was greater for Katahdin than for Alpine (p < 0.001; 180 vs. 88 g, SEM = 5.0) and ranked (p < 0.05) ALF > ALF+LES > LES (159, 132, and 111 g, respectively; SEM = 6.1). The ruminal methane emission differed (p < 0.05) between animal types in MJ/day (1.17 and 1.44), kJ/g DM intake (1.39 and 1.23), and kJ/g ADG (18.1 and 9.8 for Alpine and Katahdin, respectively). Regardless of the period and animal type, diet did not impact methane emission in MJ/day or relative to DM intake, BW, or ADG (p > 0.05). The digestible and metabolizable energy intakes, heat production, and retained energy were not affected by diet (p > 0.05). In conclusion, future research should consider the marked potential effect of CT of forages such as lespedeza on nitrogen digestion and associated effects on protein status and other conditions that may be impacted.

The effect of ensiled paulownia leaves in a high-forage diet on ruminal fermentation, methane production, fatty acid composition, and milk production performance of dairy cows

BACKGROUND

The use of industrial by-products rich in bioactive compounds as animal feeds can reduce greenhouse gas production. Paulownia leaves silage (PLS) was supplemented to dairy cows' diet and evaluated in vitro (Exp. 1; Rusitec) and in vivo (Exp. 2, cannulated lactating dairy cows and Exp. 3, non-cannulated lactating dairy cows). The study investigated the PLS effect on ruminal fermentation, microbial populations, methane production and concentration, dry matter intake (DMI), and fatty acid (FA) proportions in ruminal fluid and milk.

RESULTS

Several variables of the ruminal fluid were changed in response to the inclusion of PLS. In Exp. 1, the pH increased linearly and quadratically, whereas ammonia and total volatile fatty acid (VFA) concentrations increased linearly and cubically. A linear, quadratic, and cubical decrease in methane concentration was observed with increasing dose of the PLS. Exp. 2 revealed an increase in ruminal pH and ammonia concentrations, but no changes in total VFA concentration. Inclusion of PLS increased ruminal propionate (at 3 h and 6 h after feeding), isovalerate, and valerate concentrations. Addition of PLS also affected several populations of the analyzed microorganisms. The abundances of protozoa and bacteria were increased, whereas the abundance of archaea were decreased by PLS. Methane production decreased by 11% and 14% in PLS-fed cows compared to the control in Exp. 2 and 3, respectively. Exp. 3 revealed a reduction in the milk protein and lactose yield in the PLS-fed cows, but no effect on DMI and energy corrected milk yield. Also, the PLS diet affected the ruminal biohydrogenation process with an increased proportions of C18:3 cis-9 cis-12 cis-15, conjugated linoleic acid, C18:1 trans-11 FA, polyunsaturated fatty acids (PUFA), and reduced n6/n3 ratio and saturated fatty acids (SFA) proportion in milk. The relative transcript abundances of the 5 of 6 analyzed genes regulating FA metabolism increased.

CONCLUSIONS

The dietary PLS replacing the alfalfa silage at 60 g/kg diet can reduce the methane emission and improve milk quality with greater proportions of PUFA, including conjugated linoleic acid, and C18:1 trans-11 along with reduction of SFA. Graphical abstract of the experimental roadmap.

The Effect of Phytonutrients in Terminalia chebula Retz. on Rumen Fermentation Efficiency, Nitrogen Utilization, and Protozoal Population in Goats

The aim of this study was to investigate the effect of Terminalia chebula meal (TCM) supplementation on digestibility, rumen fermentation, nitrogen utilization, and protozoal population in goats. Eight goats with an initial body weight (BW) of 13 ± 3.0 kg were randomly assigned according to a double 4 × 4 Latin square design to receive different levels of TCM supplementation at 0, 8, 16, and 24 g/kg of total dry matter (DM) intake, respectively. The goats were fed with concentrate diets at 13 g/kg BW, while rice straw was used as a roughage source, fed ad libitum. The results revealed that the feed intake and the apparent digestibility of DM, organic matter (OM), neutral detergent fiber (NDF), and acid detergent fiber (ADF) were similar among the treatments (p > 0.05). However, crude protein (CP) digestibility decreased significantly (p < 0.05) when supplemented with TCM at 24 g/kg of total DM intake (p < 0.05). The addition of TCM did not change the ruminal pH and blood urea nitrogen concentrations (p > 0.05), whereas the concentration of NH3-N at 4 h post feeding was reduced with the inclusion of TCM at 16 and 24 g/kg of total DM intake. The total numbers of bacteria were enhanced by the addition of TCM, while the protozoal population, in both entodiniomorph and holotrich, was reduced (p < 0.05). The supplementation of TCM did not change the concentration of total volatile fatty acids (TVFA), acetic acid, or butyric acid, while the propionic acid concentration at 4-h post feeding increased significantly, especially when supplemented at 16 g/kg of total DM intake (p < 0.05. In addition, urinary nitrogen (N) excretion decreased, while fecal N excretion, N absorption, N retention, and the proportion of N retention to N intake increased with the inclusion of TCM at all levels. In summary, the inclusion of TCM could improve rumen fermentation efficiency and N balance without having an adverse effect on feed intake, nutrient digestibility, and rumen ecology; however, the protozoal population decreased. Therefore, this study suggests that TCM (16 g/kg of total DM intake) could be used as a plant source for rumen enhancement in goats fed a diet based on rice straw without having an adverse effect on feed intake or nutrient digestion. However, further studies on the production of types of meat and milk that have a long-term feeding trial should be carried out.

Crystal structure, Hirshfeld surface analysis and DFT calculations of (E)-3-[1-(2-hy-droxy-phenyl-anilino)ethyl-idene]-6-methyl-pyran-2,4-dione

The asymmetric unit of the title compound, C₁₄H₁₃NO₄, contains three independent mol-ecules, which differ slightly in conformation. Each contains an intra-molecular N-H⋯O hydrogen bond. In the crystal, O-H⋯O hydrogen bonds form chains of mol-ecules, which are linked into corrugated sheets parallel to (03) plane by C-H⋯O hydrogen bonds together with π inter-actions between the carbonyl groups and the 2-hy-droxy-phenyl rings. The layers are linked by further C-H⋯O hydrogen bonds. The Hirshfeld surface analysis of the crystal structure indicates that the most important contributions for the crystal packing are from H⋯H (49.0%), H⋯O/O⋯H (28.3%) and H⋯C/C⋯H (10.9%) inter-actions. van der Waals inter-actions are the dominant inter-actions in the crystal packing. Moreover, density functional theory (DFT) optimized structures at the B3LYP/ 6-311 G(d,p) level are compared with the experimentally determined mol-ecular structure in the solid state. The HOMO-LUMO behavior was elucidated to determine the energy gap of 4.53 eV.

Effect of microbial community structures and metabolite profile on greenhouse gas emissions in rice varieties

Rice paddy fields are major sources of atmospheric methane (CH₄) and nitrous oxide (N₂O). Rice variety is an important factor affecting CH₄ and N₂O emissions. However, the interactive effects of rice metabolites and microorganisms on CH₄ and N₂O emissions in paddy fields are not clearly understood. In this study, a high greenhouse gas-emitting cultivar (YL 6) and a low greenhouse gas-emitting cultivar (YY 1540) were used as experimental materials. Metabolomics was used to examine the roots, root exudates, and bulk soil metabolites. High-throughput sequencing was used to determine the microbial community composition. YY 1540 had more secondary metabolites (flavonoids and isoflavonoids) in root exudates than YL 6. It was enriched with the uncultured members of the families Gemmatimonadanceae and Rhizobiales_Incertae_Sedis in bulk soil, and genera Burkholderia-Caballeronia-Paraburkholderia, Magnetospirillum, Aeromonas, and Anaeromyxobacter in roots, contributing to increased expression of pmoA and nosZ genes and reducing CH₄ and N₂O emissions. YL 6 roots and root exudates contained higher contents of carbohydrates [e.g., 6-O- acetylarbutin and 2-(3- hydroxyphenyl) ethanol 1'-glucoside] than those of YY 1540. They were enriched with genera RBG-16-58-14 in bulk soil and Exiguobacterium, and uncultured member of the Kineosporiaceae family in roots, which contributed to increased expression of mcrA, ammonia-oxidizing archaea, ammonia-oxidizing bacteria, nirS, and nirK genes and greenhouse gas emissions. In general, these results established a link between metabolites, microorganisms, microbial functional genes, and greenhouse gas emissions. The metabolites of root exudates and roots regulated CH₄ and N₂O emissions by influencing the microbial community composition in bulk soil and roots.

Acacia nilotica leaf meal - potential supplement to 25% dorper crosses of local sheep fed a basal diet of natural pasture hay

This research was conducted to evaluate the replacement potential of Acacia nilotica dried leaf meal for Noug Seed Cake (NSC) to supplement low quality grass hay in the diet of crossbred sheep (25% Dorper). In doing so, four treatments were set up in such a way that 0%, 33%, 67%, and 100% NSC is replaced with dried leaf of Acacia nilotica from a conventional supplement while the treatments were kept isonitrogenous. The experiment was set up in a Randomized Complete Block Design, with initials weight used as the blocking factor. Twenty animals were allocated to the four treatments. The experiment consisted of hundred days of feeding trial followed by evaluation of carcass components at the end. In addition, the experimental feed ingredient was studied in vitro for gas production, methane (CH₄) production, fractional rate of degradation (Kd), and in vitro dry matter digestibility (IVDMD). In view of chemical composition, grass hay contained lower crude protein (CP = 3.2% DM) and high cell wall contents that makes it lower quality feed. On the other hand, Acacianilotica leaf meal was moderate in quality (CP = 14.3% DM) that can support moderate level of ruminant production. In an in vitro study, Acacia nilotica was found to have lower (P < 0.01) levels of CH₄, total gas, kd, and IVDMD compared to the other feed ingredients. This indicates that tannin have an effect on Acacia nilotica feed. Partial and complete replacement of NSC with Acacia nilotica leaf meal significantly increased total dry matter intake (TDMI) (P < 0.001). Average daily gain (ADG) and dressing percentage was also higher for leaf meal supplemented groups. Hot carcass weight was in the range of 14.8–17.8 kg, which is higher than the national average carcass weight for Ethiopian sheep, and it was also found to be higher when NSC was partially (33%) as well as completely replaced by the leaf meal. In general, NSC can be replaced either partially or completely with Acacianilotica leaf meal in the diet of 25% Dorper crosses while weight gain as well as carcass yield is promoted. The maximum inclusion level of Acacia nilotica was 61.3% or 319.2 g per day for 25% Dorper cross sheep fed natural pasture hay as a basal diet.

Differential Flavonoids and Carotenoids Profiles in Grains of Six Poaceae Crops

Poaceae practically dominate staple crops for humans. In addition to the issue of sustenance, there is a growing interest in the secondary metabolites of these staple crops and their functions on health. In this study, metabolomic variations were investigated among six important species of Poaceae with a total of 17 cultivars, including wheat, maize, rice, sorghum, foxtail millet, and broomcorn millet. A total of 201 flavonoid metabolites and 29 carotenoid metabolites were identified based on the UPLC-ESI-MS/MS system. Among them, 114, 128, 101, 179, 113, and 92 flavonoids and 12, 22, 17, 15, 21, and 18 carotenoids were found in wheat, maize, rice, sorghum, foxtail millet, and broomcorn millet, respectively. Only 46 flavonoids and 8 carotenoids were shared by the six crops. Crop-specific flavonoids and carotenoids were identified. Flavone, anthocyanins, flavanone and polyphenol were the major metabolite differences, which showed species specificity. The flavonoid content of the grains from 17J1344 (sorghum), QZH and NMB (foxtail millet) and carotenoids from Mo17 (maize) were higher than the other samples. This study provides a better knowledge of the differences in flavonoid and carotenoid metabolites among Poaceae crops, as well as provides a theoretical basis for the identification of functional metabolites in these grains.

Effect of Paulownia Leaves Extract Levels on In Vitro Ruminal Fermentation, Microbial Population, Methane Production, and Fatty Acid Biohydrogenation

Paulownia is a fast-growing tree that produces a huge mass of leaves as waste that can be used as a feed source for ruminants. The previous study showed that phenolic compounds were the most active biological substances in Paulownia leaves, which affected the ruminal parameters and methane concentration. However, there are no scientific reports on the Paulownia leaves extract (PLE) containing phenolic compounds for their mode of action in the rumen. Phenolics constituted the main group of bioactive compounds in PLE (84.4 mg/g dry matter). PLE lowered the concentration of ammonia, modulated the VFA profile in the ruminal fluid, and decreased methane production. The PLE caused a significant reduction of in vitro dry matter degradability, reduced the number of methanogens and protozoa, and affected selected bacteria populations. PLE had a promising effect on the fatty acid profile in the ruminal fluid. Paulownia as a new dietary component or its extract as a feed additive may be used to mitigate ruminal methanogenesis, resulting in environmental protection and reducing ruminal biohydrogenation, improving milk and meat quality.

Physiological responses and adaptations to high methane production in Japanese Black cattle

In this study, using enteric methane emissions, we investigated the metabolic characteristics of Japanese Black cattle. Their methane emissions were measured at early (age 13 months), middle (20 months), and late fattening phases (28 months). Cattle with the highest and lowest methane emissions were selected based on the residual methane emission values, and their liver transcriptome, blood metabolites, hormones, and rumen fermentation characteristics were analyzed. Blood β-hydroxybutyric acid and insulin levels were high, whereas blood amino acid levels were low in cattle with high methane emissions. Further, propionate and butyrate levels differed depending on the enteric methane emissions. Hepatic genes, such as SERPINI2, SLC7A5, ATP6, and RRAD, which were related to amino acid transport and glucose metabolism, were upregulated or downregulated during the late fattening phase. The above mentioned metabolites and liver transcriptomes could be used to evaluate enteric methanogenesis in Japanese Black cattle.

Enhancing Rumen Fermentation Characteristic and Methane Mitigation Using Phytonutrient Pellet in Beef Cattle

The objective of this experiment was to assess the effects of chaya (Cnidoscolus aconitifolius) leaf and rambutan (Nephelium lappaceum L.) fruit peel pellet (CRP) supplementation on rumen fermentation, feed intake, nutrient digestibility, and nitrogen balance in crossbred beef cattle. Four beef cattle crossbred bulls (Brahman 75% × Thai native 25%), with 250 ± 15 kg of liveweight at 18 months old, were randomly selected to receive four dietary treatment groups: no supplementation (control) and the supplementation of CRP at 2, 4 and 6% of dry matter intake (DMI) by using a 4 × 4 Latin square design. The cattle were fed a concentrate at 2 kg/day, and rice straw was offered ad libitum. The results showed that rumen pH at 4 h and average post-feeding values were in the normal range, though they were slightly reduced with CRP supplementation at 4 and 6% DMI (p < 0.05). Rumen temperature, ammonia nitrogen level, and total volatile fatty acid (VFA), acetate (C2), and butyrate (C4) production were similar among treatments. Nevertheless, propionate (C3) concentration was significantly increased (p < 0.05) in the CRP groups at 2 and 4% DMI. In addition, the C2/C3 ratio and CH4 production were significantly reduced in the CRP groups, especially at 2 and 4% DMI. Rice straw intake and total feed intake in terms of %BW were significantly higher in the groups with CRP at 2 and 4% DMI (p < 0.05). The apparent nutrient digestibilities were not affected by the treatments. Nitrogen intake, nitrogen absorption, and nitrogen retention were significantly enhanced by the CRP supplementation (p < 0.05). Moreover, feces and total nitrogen excretion were not different among treatments (p > 0.05). Ultimately, the supplementation of CRP at 2 and 4% DMI significantly improved the C3 concentration, reduced the C2/C3 ratio, mitigated methane production, and enhanced feed intake and nitrogen utilization efficiency. Therefore, CRP supplementation shows promise as a rumen dietary enhancer.

Ruminal Microbiome Manipulation to Improve Fermentation Efficiency in Ruminants

The rumen is an integrated dynamic microbial ecosystem composed of enormous populations of bacteria, protozoa, fungi, archaea, and bacteriophages. These microbes ferment feed organic matter consumed by ruminants to produce beneficial products such as microbial biomass and short-chain fatty acids, which form the major metabolic fuels for ruminants. The fermentation process also involves inefficient end product formation for both host animals and the environment, such as ammonia, methane, and carbon dioxide production. In typical conditions of ruminal fermentation, microbiota does not produce an optimal mixture of enzymes to maximize plant cell wall degradation or synthesize maximum microbial protein. Well-functioning rumen can be achieved through microbial manipulation by alteration of rumen microbiome composition to enhance specific beneficial fermentation pathways while minimizing or altering inefficient fermentation pathways. Therefore, manipulating ruminal fermentation is useful to improve feed conversion efficiency, animal productivity, and product quality. Understanding rumen microbial diversity and dynamics is crucial to maximize animal production efficiency and mitigate the emission of greenhouse gases from ruminants. This chapter discusses genetic and nongenetic rumen manipulation methods to achieve better rumen microbial fermentation including improvement of fibrolytic activity, inhibition of methanogenesis, prevention of acidosis, and balancing rumen ammonia concentration for optimal microbial protein synthesis.