Dynamics of methanogenesis, ruminal fermentation and fiber digestibility in ruminants following elimination of protozoa: a meta-analysis

Li, Zongjun; Deng, Qi; Liu, Yangfan; Yan, Tao; Li, Fēi; Cao, Yangchun; Yao, Junhu

doi:10.1186/s40104-018-0305-6

Cited by 31 publications

(21 citation statements)

References 57 publications

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“…These observations are consistent with the evidence that ciliates survive by digesting rumen bacteria, thus playing an important role in the inefficient use of dietary protein by ruminants and that protozoa are indirectly involved in methane production, as they harbour an active population of methanogenic archaea both on their external and internal surfaces (Morgavi et al, 2010). A recent meta-analysis exploring time-dependent effects of removing protozoa (Li et al, 2018) concluded that subsequent increases in methanogens, fungi and cellulolytic bacteria counteracted defaunation-induced effects on rumen fermentation, suggesting that defaunation might not always lead to lower levels of methane production. Protozoa also seem to stabilize rumen fermentation increasing rumen pH (Williams and Coleman, 1992), possibly because protozoa consume lactate more rapidly than bacteria (Newbold et al, 1986).…”

Section: Protozoasupporting

confidence: 83%

Review: Ruminal microbiome and microbial metabolome: effects of diet and ruminant host

Newbold

Ramos-Morales

2020

Animal

140

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The rumen contains a great diversity of prokaryotic and eukaryotic microorganisms that allow the ruminant to utilize ligno-cellulose material and to convert non-protein nitrogen into microbial protein to obtain energy and amino acids. However, rumen fermentation also has potential deleterious consequences associated with the emissions of greenhouse gases, excessive nitrogen excreted in manure and may also adversely influence the nutritional value of ruminant products. While several strategies for optimizing the energy and nitrogen use by ruminants have been suggested, a better understanding of the key microorganisms involved and their activities is essential to manipulate rumen processes successfully. Diet is the most obvious factor influencing the rumen microbiome and fermentation. Among dietary interventions, the ban of antimicrobial growth promoters in animal production systems has led to an increasing interest in the use of plant extracts to manipulate the rumen. Plant extracts (e.g. saponins, polyphenol compounds, essential oils) have shown potential to decrease methane emissions and improve the efficiency of nitrogen utilization; however, there are limitations such as inconsistency, transient and adverse effects for their use as feed additives for ruminants. It has been proved that the host animal may also influence the rumen microbial population both as a heritable trait and through the effect of early-life nutrition on microbial population structure and function in adult ruminants. Recent developments have allowed phylogenetic information to be upscaled to metabolic information; however, research effort on cultivation of microorganisms for an in-depth study and characterization is needed. The introduction and integration of metagenomic, transcriptomic, proteomic and metabolomic techniques is offering the greatest potential of reaching a truly systems-level understanding of the rumen; studies have been focused on the prokaryotic population and a broader approach needs to be considered.

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Section: Protozoasupporting

confidence: 83%

Review: Ruminal microbiome and microbial metabolome: effects of diet and ruminant host

Newbold

Ramos-Morales

2020

Animal

140

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“…Morgavi, Marin, Jouany, and Ranilla (2012) and Li et al. (2018) associated the reduction of protozoa to a lower production of acetate and butyrate, but this condition was not confirmed in our in vitro tests (Table 2). Furthermore, tannins are known to form complexes with feed protein or inhibit the protease and urease enzymes in the rumen (Patra & Aschenbach, 2018; Patra & Saxena, 2010) thus lowering the rumen ammonia concentrations.…”

Section: Resultscontrasting

confidence: 56%

“…However, such compensation requires enough time of adaptation and the recent meta‐analysis of Li et al. (2018) suggested that after 12 weeks of defaunation, the reductions in methane are no longer evident. Moreover, Colombini et al.…”

Section: Resultsmentioning

confidence: 99%

Supplementation of diets with tannins from Chestnut wood or an extract from Stevia rebaudiana Bertoni and effects on in vitro rumen fermentation, protozoa count and methane production

Sarnataro

Spanghero

Lavrenčič

2020

Animal Physiology Nutrition

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The aim of the trial was to evaluate the effect of dietary additions of Stevia rebaudiana Bertoni extract (SB) and Chestnut wood tannin (CWT) on the in vitro rumen fermentability, protozoal population and methane yield. Both plant products were tested at 3 different levels of inclusion (0.75, 1.50 and 3.00% of incubated dry matter, DM) in a total mixed ration (TMR) for ruminants by using rumen batch culture systems and a rumen inoculum collected from sheep. Total volatile fatty acid concentration, their proportions and gas production were not modified by the plant extracts inclusion, except a significant linear increment of gas production at 24 hr for SB (p = .049). Ammonia concentration decreased (p < .05) of about 17% when 1.50 or 3.00% of CWT were included into TMR. Rumen protozoa population was depressed by the SB inclusion (p = .002) with a maximum reduction of 40% at the highest SB dosage, whereas CWT negatively affected total protozoa counts (−19%) only at the dose of 3.00%. In vitro DM and NDF degradability were not affected by the supplementation of SB and CWT, as well as the methane yield. Thus, the addition of SB and CWT decreases the in vitro protozoa population of the rumen with different intensity and without effects on fermentation parameters, apart from a reduction of nitrogen degradability caused by CWT. Despite the effect on protozoa, no decreasing effect on methane production was detected.

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“…Opposite trends of acetate and propionate molar proportion resulted in decreased A:P ratio in most of the inhibitor treatments, which is consistent with decreased A:P ratio observed in defaunated sheep fed high-concentrate diet (Mendoza et al, 1993). A similar VFA profile shift was also reported in a recent meta-analysis of the defaunation effect on rumen fermentation (Li et al, 2018). The bacterial population shifts in the inhibitor treatments could also contribute to the shifted VFA profile.…”

Section: Discussionsupporting

confidence: 85%

Inhibition of Rumen Protozoa by Specific Inhibitors of Lysozyme and Peptidases in vitro

Park

Mao

2019

Front. Microbiol.

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Defaunation studies have shown that rumen protozoa are one of the main causes of low nitrogen utilization efficiency due to their bacterivory and subsequent intraruminal cycling of microbial protein in ruminants. In genomic and transcriptomic studies, we found that rumen protozoa expressed lysozymes and peptidases at high levels. We hypothesized that specific inhibition of lysozyme and peptidases could reduce the activity and growth of rumen protozoa, which can decrease their predation of microbes and proteolysis and subsequent ammoniagenesis by rumen microbiota. To test the above hypothesis, we evaluated three specific inhibitors: imidazole (IMI), a lysozyme inhibitor; phenylmethylsulphonyl fluoride (PMSF), a serine protease inhibitor; and iodoacetamide (IOD), a cysteine protease inhibitor; both individually and in combinations, with sodium dodecyl sulfate (SDS) as a positive control. Rumen fluid was collected from two Jersey dairy cows fed either a concentrate-based dairy ration or only alfalfa hay. Each protozoa-enriched rumen fluid was incubated for 24 h with or without the aforementioned inhibitors and fed a mixture of ground wheat grain, alfalfa, and grass hays to support microbial growth. Live protozoa cells were morphologically identified and counted simultaneously at 3, 6, 12, and 24 h of incubation. Fermentation characteristics and prokaryotic composition were determined and compared at the end of the incubation. Except for IOD, all the inhibitors reduced all the nine protozoal genera identified, but to different extents, in a time-dependent manner. IOD was the least inhibitory to protozoa, but it lowered ammoniagenesis the most while not decreasing feed digestibility or concentration of volatile fatty acids (VFA). ANCOM analysis identified loss of Fibrobacter and overgrowth of Treponema, Streptococcus, and Succinivibrio in several inhibitor treatments. Functional prediction (from 16S rRNA gene amplicon sequences) using the CowPI database showed that the inhibitors decreased the relative abundance of the genes encoding amino acid metabolism, especially peptidases, and lysosome in the rumen microbiota. Overall, inhibition of protozoa resulted in alteration of prokaryotic microbiota and in vitro fermentation, and peptidases, especially cysteine-peptidase, may be targeted to improve nitrogen utilization in ruminants.

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Dynamics of methanogenesis, ruminal fermentation and fiber digestibility in ruminants following elimination of protozoa: a meta-analysis

Cited by 31 publications

References 57 publications

Review: Ruminal microbiome and microbial metabolome: effects of diet and ruminant host

Review: Ruminal microbiome and microbial metabolome: effects of diet and ruminant host

Supplementation of diets with tannins from Chestnut wood or an extract from Stevia rebaudiana Bertoni and effects on in vitro rumen fermentation, protozoa count and methane production

Inhibition of Rumen Protozoa by Specific Inhibitors of Lysozyme and Peptidases in vitro

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