Comparative analysis of macroalgae supplementation on the rumen microbial community: <i>Asparagopsis taxiformis</i> inhibits major ruminal methanogenic, fibrolytic, and volatile fatty acid-producing microbes <i>in vitro</i>

O’Hara, Eóin; Moote, Paul E.; Terry, Stephanie A.; Beauchemin, K. A.; McAllister, T A; Abbott, D. Wade; Gruninger, R J

doi:10.1101/2022.09.08.507231

Cited by 3 publications

(1 citation statement)

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“…Additionally, the notable effect that the inclusion of this red seaweed alters system functional distributions, is an interesting finding from the virtual experimentation. In vivo it is likely the addition of A. taxiformis has effects for the microbiome diversity and function beyond the reduction in methanogens, supporting that the newly calibrated and tested model from this work accurately reflects complex shifts in the rumen ecosystem that result from exogenous substrates in the diet (38)(39)(40).…”

Section: Discussionsupporting

confidence: 57%

Sensitivity analysis of a mechanistic model of rumen fermentation and methane production by rumen microbiota in the presence ofAsparagopsis taxiformis

Merk,

Link,

Guy

et al. 2023

Preprint

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Ruminant animals rely on microbes for the conversion of complex plant material into host accessible metabolites. During this anaerobic conversion of plant biomass, termed enteric fermentation, methanogenic archaea convert hydrogen into the potent greenhouse gas methane (CH4). The search for methane mitigation strategies to combat climate change has identified the red seaweedAsparagopsis taxiformisas a promising feed additive that, when added to a regular cattle diet, reduced enteric CH4by over 80%. A more complete understanding of microbial interactions during enteric fermentation is needed for ongoing improvement to mitigation methods. Mathematical models that permitin silicosimulation of enteric fermentation allow for the identification of key parameters that drive rumen methane production. Here we built upon an existing rumen fermentation model and calibrated it using a preliminary classification of functional microbial groups and gas emission data from a previously publishedin vitrorumen fermentation experiment, but many microbes remained functionally unclassified. The model was then used to conduct anin silicoexperiment to explore how the partition of functionally unclassified microbes into functional groups affects methane output. Thesein silicoexperiments identified that model methane production is more sensitive to microbial variation in the presence ofA. taxiformisversus without. The use of local and global sensitivity analysis approaches revealed other rumen parameters to also be drivers of enteric methane production. In the presence ofA. taxiformis, parameters modulating methane production include bromoform concentration, methanogen abundance, total microbial concentration, a parameter effecting the inhibition of methanogen growth rate by the action of bromoform, and the maximum specific utilization rate of hydrogen. WithoutA. taxiformis, feed composition parameters, the hydrolysis rate constant of cell wall carbohydrates, and a parameter affecting the yield factors during sugar utilization were found to be most significant. For possible methane reduction withoutA. taxiformis, we propose an adjustment in feed composition parameters that reduces predicted methane by 25.6%.

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Section: Discussionsupporting

confidence: 57%

Sensitivity analysis of a mechanistic model of rumen fermentation and methane production by rumen microbiota in the presence ofAsparagopsis taxiformis

Merk,

Link,

Guy

et al. 2023

Preprint

View full text Add to dashboard Cite

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Effects on rumen microbiome and milk quality of dairy cows fed a grass silage-based diet supplemented with the macroalga Asparagopsis taxiformis

et al. 2023

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The objective was to determine the effects on rumen microbiome and milk quality of reducing the methane (CH4) produced from enteric fermentation by the addition of Asparagopsis taxiformis (AT) to the diets of dairy cows. Six Nordic Red cows at 122 ± 13.7 (mean ± SD) days in milk, of parity 2.7 ± 0.52 and producing 36 kg ± 2.5 kg milk per day at the start of the trial were divided into three blocks by milk yield and assigned to an extra-period Latin-square change-over design comprising two dietary treatments. An extra period of observation was added to the Latin-square change-over design to control for carry-over effects. The dietary treatments were a diet consisting of grass silage and a commercial concentrate mixture (60:40) either not supplemented or supplemented with 0.5% AT on an organic matter intake basis. On average, daily CH4 production, CH4 yield, and CH4 intensity decreased by 60%, 54%, and 58%, respectively, in cows fed the diet supplemented with AT. Furthermore, hydrogen gas emitted by cows fed diets supplemented with AT increased by more than five times compared with cows fed a non-AT-supplemented diet. Feed intake was decreased and milk production altered, reflecting a decreased yield of milk fat in cows fed an AT-supplemented diet, but feed efficiency increased. Rumen fermentation parameters were changed to promote propionate rather than acetate and butyrate fermentation. The most prominent change in milk quality was an increase in bromine and iodine when the diet was supplemented with AT. The reduction in CH4 was associated with a shift from Methanobrevibacter to Methanomethylophilaceae in the archaeal population and a lower relative abundance of Prevotella in the bacterial population. Changes in milk fat odd-numbered and branched-chain fatty acids in the current study of AT supplementation support observed differences in ruminal archaeal and bacterial populations.

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Evaluation of the red seaweed Mazzaella japonica as a feed additive for beef cattle

et al. 2023

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Supplementing ruminant diets with macroalgae is gaining interest globally because bromoform-containing seaweeds (e.g., Asparagopsis spp.) have been shown to be highly effective enteric methane (CH4) inhibitors. Some alternative seaweeds decrease in vitro CH4 production, but few have been evaluated in animals. This study examined the effects of including the red seaweed Mazzaella japonica in the diet of beef cattle on dry matter intake (DMI), rumen fermentation, digestibility, nitrogen (N) utilization, and enteric CH4 production. Six ruminally cannulated, mature beef heifers (824 ± 47.1 kg) were used in a double 3 × 3 Latin square with 35-d periods. The basal diet consisted of 52% barley silage, 44% barley straw, and 4% vitamin and mineral supplement [dry matter (DM) basis]. The treatments were (DM basis): 0% (control), 1%, and 2% M. japonica. The DMI increased quadratically (P = 0.025) with the inclusion of M. japonica, such that the DMI of heifers consuming 1% was greater (P < 0.05) than that of control heifers. The apparent total-tract digestibility of DM decreased linearly (P = 0.002) with the inclusion of M. japonica, but there were no treatment differences in the digestibility of organic matter, crude protein (CP), neutral detergent fiber, or starch. The level of M. japonica linearly (P < 0.001) increased the N intake of the heifers. Fecal N excretion linearly increased (P = 0.020) with M. japonica, but there were no differences in total urinary N excretion, N fractions (allantoin, uric acid), total purine derivatives, microbial purine derivatives absorbed, microbial N flow, or retained N. There were no treatment effects on rumen pH or total volatile fatty acids (VFAs); however, adding M. japonica to the diet quadratically (P = 0.023) decreased the proportion of acetate, whereas 1% inclusion decreased the acetate proportion. Methane production (g/day) decreased quadratically (P = 0.037), such that the heifers receiving 2% M. japonica produced 9.2% less CH4 than control animals; however, CH4 yield (g/kg DMI) did not differ among treatments. We conclude that supplementing a forage-based diet with up to 2% M. japonica failed to lower the enteric CH4 yield of beef heifers. M. japonica can be used in diets to help meet the CP requirements of cattle, but inclusion rates may be limited by high inorganic matter proportions. When comprising up to 2% of the diet, M. japonica cannot be recommended as a CH4 inhibitor for beef cattle fed on high-forage diets.

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Comparative analysis of macroalgae supplementation on the rumen microbial community: Asparagopsis taxiformis inhibits major ruminal methanogenic, fibrolytic, and volatile fatty acid-producing microbes in vitro

Cited by 3 publications

References 67 publications

Sensitivity analysis of a mechanistic model of rumen fermentation and methane production by rumen microbiota in the presence ofAsparagopsis taxiformis

Sensitivity analysis of a mechanistic model of rumen fermentation and methane production by rumen microbiota in the presence ofAsparagopsis taxiformis

Effects on rumen microbiome and milk quality of dairy cows fed a grass silage-based diet supplemented with the macroalga Asparagopsis taxiformis

Evaluation of the red seaweed Mazzaella japonica as a feed additive for beef cattle

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