https://doi.org/10.22319/rmcp.v16i2.6629

Article

Potential of a phytobiotic based on Acacia concinna and the red seaweed Palmaria palmata to reduce in vitro ruminal methane production

 

Oscar Ponce-Pérez ^a

German David Mendoza-Martínez ^a,b

Pedro Abel Hernández-García ^c

Adrián Gloria-Trujillo ^a,b

María Eugenia de la Torre-Hernández ^a,d*

Héctor Aaron Lee-Rangel ^e

Rogelio Flores-Ramírez ^e

José Alejandro Roque-Jiménez ^f

 

^a Universidad Autónoma Metropolitana- Xochimilco. División de Ciencias Biológicas. Doctorado en Ciencias Agropecuarias. Ciudad de México, México.

^b Universidad Autónoma Metropolitana- Xochimilco. Departamento de Producción Agrícola y Animal. México.

^c Universidad Autónoma del Estado de México. Centro Universitario UAEM Amecameca. México.

^d Secihti - Universidad Autónoma Metropolitana- Xochimilco. México.

^e Universidad Autónoma de San Luis Potosí. Facultad de Agronomía. México.

^f Universidad Autónoma de Baja California, Instituto de Ciencias Agrícolas. México.

 

*Corresponding author: mdelatorre@correo.xoc.uam.mx

 

Abstract:

Changes in methane and carbon dioxide production and their effects on the ruminal microbiota were evaluated in vitro by incubating alfalfa with an herbal additive formulated with Acacia concinna and with a supplement containing red seaweed Palmaria palmata. The metabolites of the supplement with Palmaria palmata were characterized, and 20 chemical compounds were found, of which phenols, terpenes, halogenated compounds, and alkanes stood out. The inclusion of the herbal additive reduced (P<0.01) ruminal methane by 29 % and red seaweed by 56 %. The volatile fatty acid (VFA) molar concentration increased (P<0.05) with the seaweed additive. The two additives increased the proportions of acetate and propionate and reduced that of butyrate (P<0.05) compared to the control. No differences (P>0.05) were detected in the abundance of most microbial families, only minor changes in Rikenellaceae; just Cellulomonadaceae increased significantly (P>0.001) with the herbal additive. The two additives showed methane reductive potential, which was more pronounced for Palmaria palmata.

Keywords: Gas production, Methanogenesis, Natural additive, VFA.

 

Received: 29/01/2024

Accepted: 07/05/2025

 

 

Introduction

Against the background of a changing climate, it is crucial to reduce ruminal methane emissions, in addition to the fact that methane emission represents an energy loss for ruminants⁽¹⁾. Among the natural compounds that can reduce methane are plant saponins⁽²⁾, available in some polyherbal mixtures⁽³⁾, and the halogenated compounds synthesized by some seaweed species^(4,5).

A previously described herbal additive based on Acacia concinna has a standardized content of saponins and shows biological effects similar to those of coccidiostats in broilers⁽³⁾. It affects the productive performance of feedlot lambs⁽⁶⁾ and dairy calves⁽⁷⁾ and also contains other secondary metabolites, highlighting 43 organic compounds such as thymol, cinnamon, caryophyllene, phenols, oleic acid, polyunsaturated fatty acids, and vitamin E⁽⁷⁾.

Saponins have toxic effects on protozoa but also form complexes with the lipid membrane of bacteria, affecting some bacterial populations⁽²⁾. The inclusion of saponins at low dietary concentrations can be beneficial for ruminants, improving ruminal fermentation efficiency by decreasing methanogenesis, which is associated to the saponin effects on Archaea and rumen protozoa^(8-11).

Some species of the red macroalgae genus Asparagopsis produce metabolites with anti-methanogenic effects^(12-16), and there is evidence that Asparagopsis taxiformis can significantly reduce methane emissions in sheep⁽¹⁷⁾ and beef cattle^(18,19). However, other algae species should be evaluated in terms of their methane reduction potential based on their biochemical characteristics^(20,21). When comparing different seaweed species in in vitro ruminal assays, Palmaria palmata showed higher digestibility and gas production as well as volatile fatty acid (VFA) and propionate concentrations than other species and produced lower ruminal methane concentrations⁽²²⁾. Palmaria palmata is a red alga (Rhodophyta) formerly called Rhodymenia palmata (Linnaeus) and belongs to the family Palmariaceae⁽²³⁾. It has been subjected to different forms of cultivation⁽²⁴⁾ and is marketed as a supplement for human consumption, making it available as a feed additive for ruminants. In this context, the objective of this study was to compare the in vitro methane reduction potential of a feed plant additive made from Acacia concinna versus a product made from Palmaria palmata, evaluating the changes in methane production, ruminal fermentation and effects on the rumen microbiota.

 

 

 

Material and methods

Animals and inoculum

The ruminal inoculum was collected by a trained veterinarian from crossed lambs with an esophageal probe in preprandial conditions in order to reduce variation⁽²⁵⁾. The procedures were approved by the Animal Welfare Committee of the UAEM Amecameca University Center of the Autonomous University of the State of Mexico (Protocol #0201-2023). The donors of ruminal liquid were fed a diet with 75 % corn silage and 25 % commercial concentrate with 12 % crude protein. This fluid used as inoculum, was placed in a thermo at 39 ºC and transported to the nutrition laboratory, where it was filtered through four layers of cheese cloth and saturated with carbon dioxide.

 

Additives evaluated

Two commercial products were tested: the herbal product formulated with Acacia concinna (Peptasan^®, Indian Herbs Specialties Pvt and Nuproxa Mexico) and the red seaweed capsules (Solaray Inc; Salt Lake City, UT) elaborated with Palmaria palmata, which can be obtained via the internet as supplement for human consumption.

 

Product characterization

Samples of the red seaweed Palmaria palmata were used to characterize the secondary metabolites using a gas chromatograph coupled to a mass spectrometer (GC-MS). Extraction was performed using an ultrasonic processor (GEX130, 115 V 50/60 Hz) equipped with a 3-mm titanium tip and mechanical stirrers (Cole-Parmer, IL, USA) as described by Roque-Jiménez et al⁽²⁶⁾. One gram of red seaweed product was mixed with 10 mL of hexane to separate the organic phase by an ultrasonic processor with a 70 % amplitude and centrifuged at 3,500 rpm for 5 min, followed by concentration in a water bath with a direct CO₂ probe for 5 min at 37 °C to recover 1 mL of the extracted mixture (Zymark, Turbovap LV Concentration Evapotarot, NB, USA). The metabolites were characterized by a gas chromatograph (GC-HP 6890) coupled to a mass spectrophotometer (MSHP 5973), using a capillary column (60 m in length, 0.255 mm in diameter, 0.25 µm in thickness) (HP 5MS, Agilent) under conditions described by Roque-Jiménez et al⁽²⁶⁾. The herbal product was previously characterized by Lee et al⁽⁷⁾ and saponins content reported by Sánchez-Hernández et al⁽³⁾.

 

In vitro gas production and rumen fermentation

Alfalfa was incubated as a main substrate with 0 % and 2 % red seaweed or herbal additive, using five 120 ml amber flasks for each treatment and their controls; two runs were conducted. Each flask contained 0.5 g of alfalfa ground to a particle size of 2 mm and 90 mL of ruminal fluid (added to each flask with a continuous flow of CO₂) and was sealed. Five flasks were included as blanks containing only ruminal inoculum. The flasks were placed in a water bath at 39 ºC, and the gas pressure was recorded at 3, 6, 9, 12, 24, 36, and 48 h of incubation using a manual manometer (Amphenol SSI Technologies)⁽²⁷⁾. To estimate CH₄ and CO₂, it was used the methodology proposed by Menke and Steingass⁽²⁸⁾, recording the gas volume accumulated up to 48 h with a 60-mL graduated hypodermic syringe. In each measurement, the gas trapped in the syringe was transferred by injection to another hermetically closed flask, which contained 40 mL of a sodium hydroxide solution (1M KOH) prepared with distilled water, mixing the gas to fix the carbon dioxide to form potassium bicarbonate^(29,30). The residual volume was used to estimate methane⁽³¹⁾.

Flasks were filtered at the final incubation time to estimate the percentage of dry matter disappearance. A subsample of ruminal fluid at 24 h of incubation was acidified with metaphosphoric and frozen until the analysis of VFA by gas chromatography⁽³²⁾, using a Perkin Elmer Clarus 580 with a capillary column of 30 m x 0.25 mm x 25 µm (Agilent Technologies model HP-FFAP) and nitrogen as carrier gas.

 

DNA isolation and metagenomic analyses

Ruminal fluid from six tubes at 12 h of fermentation were cryopreserved and stored immediately at -80 °C until DNA extraction; 2 mL of each sample were mixed with 6 mL of DNA/RNA Shield (Zymo Research, Cat. No.: R1100-250; Lot. No.: 219429) and sent to Zymo Research (Irvine, CA) for metagenomic-DNA extraction, quantification, sequencing and analysis by the targeted sequencing service for microbiome, as described by Mendoza-Martínez et al⁽³³⁾.

Sequencing of the microbial 16S rRNA gene was performed using the Quick-16S™ NGS library preparation kit (Zymo Research, Irvine, CA). The V3–V4 region of this gene was amplified with specific primers custom-designed by Zymo Research. The final pooled library was cleaned with Select-a-Size DNA Clean & Concentrator™ (Zymo Research, Irvine, CA) and subsequently quantified with TapeStation™ (Agilent Technologies, Santa Clara, CA) and Qubit™ (Thermo Fisher Scientific, Waltham, WA). As a positive control for each targeted library preparation, the ZymoBIOMICS™ microbial community DNA standard (Zymo Research, Irvine, CA) was employed. Negative controls (i.e., extraction control blank and library preparation control blank) were included to assess the level of bioburden inherent in the extraction process. The final library was sequenced on the Illumina MiSeq™ platform with a v3 reagent kit (600 cycles). Sequencing was done with a 10 % PhiX peak. Unique amplicon sequence variants were inferred from raw reads, using DADA2 pipeline⁽³⁴⁾, which also served to eliminate chimeric sequences. The taxonomy assignment was carried out using Uclust from Qiime v. 1.9.1⁽³⁵⁾ with Zymo's own database. Composition as well as alpha and beta diversity analyses were also performed with Qiime v. 1.9.1.

 

Statistical analysis

Data normality was tested with the Shapiro Wilk test, and the results were analyzed in a completely randomized block design⁽³⁶⁾ using run as a blocking criterion with the following model:

Y_i = 𝜇 + B_i + T_j + B_{i *} T_j +  e_ij

Where:

Y is the dependent variable,

𝜇 is the overall population of the mean,

B_i is the fix effect of run (Block),

T_i is the fix effect of treatment,

eij is the residual error, using the Block x treatment interactions a an experimental error⁽³⁷⁾.

 

When significant effects were detected, and means were compared by orthogonal contrasts. The in vitro gas production kinetics parameters (lag phase (h), maximum volume (Vm), and gas production rate (S)) were estimated with the model Vo= Vm / (1 + e (2-4 * s * (tL))), proposed by Menke and Steingass⁽²⁸⁾ and parameters were estimated by non-linear regression⁽³⁸⁾. Software used was SAS® OnDemand for Academics (https://www.sas.com/en_us/software/on-demand-for-academics.html).

 

 

 

Results

Product characterization

Gas chromatography coupled with mass spectrophotometry revealed 20 chemical compounds present in Palmaria palmata (Table 1), including a variety of phenols, terpenes, and alkanes such as heptadecane, followed by glycerol tricaprylate, which is a triglyceride of octanoic acid esters and other components such as 1,2-benzenedicarboxylic acid and dioctyl ester.

 

 

Table 1: Identification of volatile compounds in the red seaweed Palmaria palmata supplement using gas chromatograph coupled to a mass spectrometer

NAI= Not available information.

 

 

In vitro gas production and rumen fermentation

In vitro gas production (Table 2) was reduced with the addition of the herbal product and red seaweed by 2 % and 7 %, respectively, compared to that of the control group. The gas production rate was slower with red seaweed (P<0.01), whereas the lag phase and the in vitro dry matter (DM) digestibility were not affected. Methane was reduced (P<0.01) with the herbal additive by 29 % and by 56 % with the red seaweed in comparison with that of the controls; however, the CO₂ level was not affected. The molar VFA concentration increased (P<0.05) with the red seaweed additive, which showed greater proportion of acetate and reduced propionate and butyrate levels (P<0.01) compared to those of the control group. The herbal product results in increased proportions of acetate and reduced propionate levels (P<0.05).

 

 

Table 2: Effects of a phytobiotic based on Acacia concinna and a commercial supplement containing red seaweed Palmaria palmata on kinetics of in vitro gas production, ruminal fermentation and methane

V max= maximum volume of gas; S= rate of gas production; Lag= lag phase; IVDMD= in vitro dry matter digestibility; SEM= standard error of the mean. ^xPeptasan^® herbal additive.

 

 

Metagenomic analyses

From the 6 samples, were obtained 2’630,796 raw sequences in total from the V3–V4 region of the 16S rRNA gene, within a range of 208,618 to 571,150 (average 438,466 sequences per sample). After performing quality filtering, as well as chimera detection and elimination (117,294 sequences), the total unique amplicon sequence variants (ASV) analyzed were 874,117, in a range of 67,716 to 213,108 (average 148,216 per sample). Shannon (homogeneity) and Simpson reciprocal (diversity) indices, as well as Chao1 richness estimator, were calculated for each treatment (Table 3), having been normalized to 20,000 sequences.

 

 

Table 3: Effects of a phytobiotic based on Acacia concinna and a commercial supplement containing red seaweed Palmaria palmata on ruminal microbial diversity

SEM= standard error of the mean. ^X: Peptasan® herbal additive.

 

 

Analysis of alpha diversity indexes of the microbial communities of the rumen did not show significant differences between treatments. However, the tendency to decrease species richness was detected in the presence of the polyherbal additive (Table 3, Chao1), probably due to the presence of diverse plant secondary metabolites with antimicrobial activity, as will be discussed further.

Twenty-one (21) bacterial/archaeal families with a relative abundance >0.1 % were identified in any of the samples (Table 4); families with lower abundances were grouped into "others". No significant differences (P>0.05) were detected for most of the microbial families. The abundance of methanogenic Archaea was not affected with the herbal product, but apparently increased by  50 % with the red seaweed.  The abundance of Rikenellaceae was reduced by 8 % with red seaweed and by 36 % with the herbal additive, as well as Micrococcaceae, which apparently disappear with red seaweed, and was reduced 93 % with herbal additive. Microbacteriaceae family could only be detected in the treatments with the herbal additive, which was also the case for Corynebacteriaceae, and Sanguibacteraceae, albeit without a statistically significant difference. In turn, Cellulomonadaceae was increased by 650 % with red algae and 9,000 % (P>0.001) with the additive.

 

 

Table 4: Effects of a phytobiotic based on Acacia concinna and a commercial supplement containing red seaweed Palmaria palmata on the ruminal microbial relative abundances (Family level) evaluated in vitro

RS= red seaweed; HA= herbal additive; SEM= standard error of the mean. HA= Peptasan^® herbal additive.

 

 

 

Discussion

In vitro studies have been used to identify products that can reduce ruminal methane, however, in vivo evaluations are required to confirm the results in animal health and production⁽³⁹⁾; likewise, factors that can alter the results must be taken into account to design sampling and incubation conditions⁽²⁵⁾ that reveal useful information.

There is global interest in finding feed additives to reduce ruminal methane emissions, using metabiotic methane inhibitors⁽⁴⁰⁾, seaweeds⁽⁴¹⁾, and other phytobiotics. Bunglavan et al⁽⁴²⁾ evaluated various herbs and their extracts regarding their potential to reduce methane production. According to these authors, extracts of Acacia concinna had the highest potential for inhibiting methanogenesis compared to those of the other herbs, confirming the results found here.

Palmaria palmata contained high levels of alkanes (Table 1), such as heptadecane, which, similar to 10, 14-trimethyl-2-pentadecanone, have antidiarrheal properties by deactivating the enzyme arginine decarboxylase in Campylobacter⁽⁴³⁾ in addition sea red has other metabolites with antibacterial effects such as 6 1,2-benzenedicarboxylic acid, diisooctyl ester⁽⁴⁴⁾, 2(4H)-benzofuranone, 5,6,7,7a-tetrahydro- 4,4,7a-trimethyl-, (R)⁽⁴⁵⁾ Silane, 1,4-phenylenebis-trimethyl-⁽⁴⁶⁾ and 3,7,11,15-Tetramethyl- 2-hexadecen-1-ol⁽⁴⁷⁾. These findings explain the changes in the VFA levels, even though there were few changes in the detected families (Table 4). Therefore, it is possible that the metabolites of the red algae have affected the ruminal protozoa which are implied in methanogenesis and the fermentation pattern⁽⁴⁸⁾. Palmaria palmata also contains a low-molecular-weight halogenated compound, namely 2(3H)-furanone, dihydro-5-tetradecyl, which may be responsible for ruminal methane reduction. The fermentation pattern suggests that the halogenated compounds reduced ruminal methane by inhibition genes expressing enzymes involved in methane synthesis, such as methyl-coenzyme M reductase (MCR)⁽⁴⁹⁾, in a similar way as the 3-NOP inhibitor, designed to inhibit MCR, which is essential for archaeal methanogenesis⁽⁴⁰⁾. Methane can be reduced not necessarily associated to an abundance reduction of Archaea, but to interference in a step of methanogenesis. The red seaweed compounds modified rumen fermentation and VFA patterns inhibiting the hydrogenotrophic methanogenesis pathway⁽²⁰⁾. In vitro methane reduction were significant (98.9 %⁽¹²⁾ and 99 %⁽⁵⁾) with Asparagopsis taxiformis, whereas in vivo reduction was lower, among 29.4 and 34.4 %⁽¹³⁾.

Methane reduction with the herbal additive could be explained by the antimethanogenic action of saponins⁽⁵⁰⁾ and by the presence of other metabolites with antibacterial and antiprotozoal effects, such as alkaloids, flavonoids, tannins, phenolic compounds, and terpenoids^(51,52), which may modulate rumen fermentation and improve nutrient use⁽⁵³⁾. In the present study, the abundance of Methanobacteriaceae was not significantly affected. The herbal additive also contains other secondary metabolites, among which are alkanes such as dotriacontane, triacontane, and docosane⁽⁷⁾, with antiviral⁽⁵⁴⁾ and antibacterial properties⁽⁵⁵⁾. Overall, the antibacterial activity of this herbal additive could be attributed to metabolites such as triacontane⁽⁵⁵⁾, oleic acid⁽⁵⁶⁾, docosane⁽⁵⁷⁾, cinnamyl cinnamate⁽⁵⁸⁾, hexadecanoic acid methyl ester⁽⁵⁹⁾, and tymol^(60-63). The saponin content in the herbal additive is 15 % of DM⁽³⁾.

Additives with high saponin levels have been evaluated in lambs⁽⁶⁾ and calves⁽⁷⁾ and resulted in reduced animal performance at higher dietary concentrations, reducing DM digestibility linearly with an increasing additive concentration⁽⁶⁾. However, in other studies, saponin-rich additives improved lamb performance in un-dewormed lambs⁽⁶⁴⁾ and immune system responses in calves⁽⁷⁾, which can be explained by their anthelmintic properties⁽³⁾. At low concentrations in the diet, saponins are beneficial for ruminants by improving fermentation efficiency, decreasing protozoan populations, and, consequently, reducing the abundances of methanogenic Archaea^(8-11). The antiprotozoal effects of saponins are due to their ability to form irreversible complexes with the lipidic protozoan cell membrane, causing membrane rupture, cell lysis, and death⁽⁶⁵⁾.

Comparatively, the magnitude of methane reduction with Palmaria palmata was greater than that observed with the herbal additive. Abbott et al⁽⁴¹⁾ observed CH₄ mitigation effects with the addition of some red seaweed species (Gigartina spp., Gracilaria vermiculophylla, Laurencia filiformis, and Hypnea pannosa) at concentrations between 40 and 60 % (and at high dry matter concentrations). In contrast, the red alga Asparagopsis taxiformis reduced the CH₄ by approximately 100 % at concentrations above and around 1 % of dry matter. Machado et al⁽⁵⁾ also reported that Asparagopsis taxiformis at 2 % of dry matter or the halogenated methane analog bromoform (5 μM) in vitro reduced methane production by more than 99 %. Further in vivo studies are needed to determine the inclusion levels of Palmaria palmata that can reduce methane emission without affecting productive performance^(20,66). Since in vitro results show a propionate reduction, the Palmaria palmata inclusion could reduce the energy from VFA for ruminants, therefore it is necessary to evaluate whether this could be compensated for the energy saved in ruminal methane.

Stoichiometric estimates of methane and CO₂ with the simplified Van Soest equations⁽⁶⁷⁾ resulted in values similar to those show in Table 2 for the CO₂ levels of the different treatment, whereas for CH₄, the estimated values were 29 % higher for the control. With the addition of Palmaria palmata and the herbal additive, the estimated values were 240 % and 99 % higher, respectively, than the observed ones. This indicates that H is being incorporated in alternative pathways in the presence of both additives, presumably in reductive acetogenesis (reduction of CO₂ with H₂ to acetate), in NH₄ cycling, and in the biohydrogenation of unsaturated fatty acids⁽⁶⁸⁾, pathways that are not considered with the stoichiometric model, which could explain the higher concentration of acetate observed with red seaweed. Other marine algae (Macrocystis pyrifera, Ulva spp., Mazzaella spp.; red algae) have shown increases or reductions in VFA concentration, have been consistent in increasing propionate in vitro⁽⁶⁹⁾.

Both additives contain unsaturated fatty acids, where double bonds follow biohydrogenation, which requires H in the rumen⁽⁷⁰⁾. The herbal additive contains oleic acid⁽⁷⁾, whereas Palmaria palmata contains pentadecanoic acid, 14-methyl -, methyl ester (Table 1), and may contribute partially to the reduction of ruminal CH₄ production⁽⁷¹⁾. In future studies it will be important to characterize the contaminating heavy metals in seaweed because some are used in human food⁽⁷²⁾ and research possibly will be included in ruminants’ feed.

In their in vitro study, Choi et al⁽⁷³⁾ evaluated four red seaweed species (Amphiroa anceps, Chondracanthus tenellus, Grateloupia elliptica, and Gracilaria parvispora) and reported methane reduction levels between 4.6 % and 51.5 %, indicating that different species can vary in their fermentation potential. Terry et al⁽⁷⁴⁾ reported that the seaweed A. taxiformis in vitro reduced the concentration of CH₄ by up to 95.1 %, reducing the total VFA concentration (reducing the proportion of acetate and increasing that of butyrate). In a study⁽⁷⁵⁾, A. taxiformis decreased the methane concentration and archaeal abundance in vitro, also reducing the total VFA level (by reducing acetate and increasing butyrate concentrations). Ahmed et al⁽⁷⁶⁾ included A. taxiformis at 2.5 % in vitro and found an 80 % reduction of CH₄ without affecting the total VFA concentration. Other seaweeds have shown inconsistency in VFA concentration response but consistently have increased propionate in vitro⁽⁶⁹⁾. In the present study, methane was reduced by 29 % with the herbal additive and by 56 % with the red seaweed compared to the control. The total VFA concentration was increased with Palmaria palmata addition, which could be a positive aspect because dietary interventions that inhibit methanogenesis are generally associated with a decreased VFA production⁽⁷⁶⁾.

The fact that both products did not reduce digestibility is important because this variable is crucial in ruminant performance⁽⁷⁷⁾. In another study, the herbal additive had no effect on the in vivo total DM digestibility in lambs receiving 4 g/d⁽⁶⁴⁾. Few studies have investigated the effects of Palmaria on in vivo digestibility, and there is no information on ruminant performance. However, in one in vitro study, Palmaria palmata increased DM digestibility, standing out among other seaweed species⁽²²⁾. Regarding the effects of Asparagopsis taxiformis, it was reported⁽⁴¹⁾ that its inclusion at 10 % had a detrimental effect on ruminal organic matter degradability. Some results⁽⁷⁸⁾ indicate that Macrocystis pyrifera and Ulva spp. have no impact on in vitro DM digestibility, whereas Mazzaella spp. reduces DM digestibility.

The biological role played of family Sanguibacteraceae is not known as well as Cellulomonadaceae, although these results showed a significant increase in this last bacterial family in response to the herbal additive, so it would be advisable to continue investigating its metabolic potential as part of the ruminal microbial community. The biological significance of some other bacterial families such as Micrococcaceae, Microbacteriaceae and Corynebacteriaceae, is not clear, but they have been related with the production of volatile sulphur compounds (VSCs) -except thioesters-⁽⁷⁹⁾, nevertheless the data did not allow the detection of statistically significant differences among them in response to treatments. In previous studies, no significant differences were observed regarding the abundances of cellulolytic bacterial families^(80,81), which are associated with a higher proportion of acetate⁽⁸²⁾, which coincides with the non-affected digestibility. The decrease in propionate could be attributed to the reduction in the abundance of species of the family Rikenellaceae, capable to produce succinate, which is subsequently catabolized to propionate^(82,83). These results confirm the potential of the evaluated products to provide benefits for ruminant performance. The potential to modify ruminal fermentation and reduce methane emissions should improve the feed efficiency in ruminants⁽⁵²⁾.

 

 

 

Conclusions and implications

The results confirm that the herbal product based on Acacia concinna and the red algae Palmaria palmata have metabolites that can reduce ruminal methane by different mechanisms of action. The methane reductive potential of both additives must be corroborated with in vivo studies to verify if the fermentation profile could be a drawback for the energy obtained from volatile fatty acids.

 

Acknowledgments

The authors thank Indian Herb Specialties Pvt and Nuproxa Mexico for providing the herbal product. As well as SECIHTI (formerly CONAHCYT) for scholarship 963486 received by OPP and its Investigadores por Mexico Program (formerly Cátedras CONAHCYT) to which METH belongs.

 

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