The Antimethanogenic Nitrocompounds Can be Cleaved into Nitrite by Rumen Microorganisms: A Comparison of Nitroethane, 2-Nitroethanol, and 2-Nitro-1-propanol

Metagenomic insights into the mechanistic differences of plant polyphenols and nitrocompounds in reducing methane emissions using the rumen simulation technique

Methane (CH4) emissions from ruminants contribute significantly to greenhouse gas levels and also result in considerable feed energy losses. Plant polyphenols and nitrocompounds are two typical types of methane inhibitors. The study investigates the mechanistic differences between 2-nitroethanol (NE) and proanthocyanidins (PAC) in reducing methane emissions from ruminant livestock using the rumen simulation technique (RUSITEC) combined with metagenomic analyses. The experiment was performed as a complete randomized block design with 3 runs. Run was used as a blocking factor. The treatments included a control (CON) with no additive, NE at 0.5 g/kg dry matter (DM), and PAC at 20 g/kg DM, all incubated in vitro for 24 h (h) with eight replicates per treatment. The results showed that NE significantly reduced CH4 production by 94.9 % (P < 0.01) and total volatile fatty acid (TVFA) concentration by 11.1 % (P < 0.05) compared to the control. NE also decreased the acetate-to-propionate ratio (A/P) from 1.93 to 1.60 (P < 0.01), indicating a shift towards more efficient fermentation. In contrast, PAC reduced methane production by 11.7 % (P < 0.05) and decreased the A/P (P < 0.05) while maintaining microbial diversity and fermentation stability, with no significant impact on TVFA concentration (P > 0.05). Metagenomic analysis revealed that NE markedly suppressed the abundance of key genera involved in carbohydrate metabolism, including Prevotella and Bacteroides, leading to reduced acetate and butyrate pathways. NE also selectively inhibited methanogenic archaea, particularly Methanobrevibacter spp., which are integral to the hydrogenotrophic pathway (P < 0.01). On the other hand, PAC showed selective inhibition of Methanosphaera spp., targeting the methylotrophic pathway (P < 0.01). These findings provide valuable insights into the distinct microbial and metabolic pathways modulated by NE and PAC, offering potential strategies for developing effective dietary interventions to mitigate methane emissions in ruminant livestock.

Effect of 3-Nitropropionic Acid at Different Doses on In Vitro Rumen Fermentation, Digestibility, and Methane Emissions of Grazing Yak and Cattle

3-nitropropionic acid (3NPA) has been proposed as an useful modifier to mitigate ruminal enteric methane emissions. However, few studies investigated the effects of 3NPA on ruminal fermentation characteristics of grazing ruminants in vitro. Rumen fluid from grazing yak and cattle were collected and incubated with additions of 0, 8, and 16 mM 3NPA. The total gas production, CH4 production, and dry matter digestibility significantly decreased with increasing 3NPA doses in both ruminant species (p < 0.05) and methane production decreased to almost 100% in cattle at 8 mM NPA but not yak, while H2 accumulation showed an opposite trend. The total fatty acid (TVFA) production, acetate concentration, and propionate concentration in cattle decreased as 3NPA doses increased at 12 and 24 h incubation. For yak, the H2 accumulation reached its apex at 8 mM NPA (p < 0.05). The TVFA in yak decreased significantly with increasing 3NPA doses at 12 and 72 h incubation. Moreover, the acetate concentration and propionate concentration in yak decreased as 3NPA doses increased at 12 and 24 h incubation. Overall, these findings demonstrated that 3NPA could be used as a strategy to mitigate methane emissions; although, it negatively affected the dry matter degradability in vitro.

Reference materials for MS-based untargeted metabolomics and lipidomics: a review by the metabolomics quality assurance and quality control consortium (mQACC)

INTRODUCTION

The metabolomics quality assurance and quality control consortium (mQACC) is enabling the identification, development, prioritization, and promotion of suitable reference materials (RMs) to be used in quality assurance (QA) and quality control (QC) for untargeted metabolomics research.

OBJECTIVES

This review aims to highlight current RMs, and methodologies used within untargeted metabolomics and lipidomics communities to ensure standardization of results obtained from data analysis, interpretation and cross-study, and cross-laboratory comparisons. The essence of the aims is also applicable to other 'omics areas that generate high dimensional data.

RESULTS

The potential for game-changing biochemical discoveries through mass spectrometry-based (MS) untargeted metabolomics and lipidomics are predicated on the evolution of more confident qualitative (and eventually quantitative) results from research laboratories. RMs are thus critical QC tools to be able to assure standardization, comparability, repeatability and reproducibility for untargeted data analysis, interpretation, to compare data within and across studies and across multiple laboratories. Standard operating procedures (SOPs) that promote, describe and exemplify the use of RMs will also improve QC for the metabolomics and lipidomics communities.

CONCLUSIONS

The application of RMs described in this review may significantly improve data quality to support metabolomics and lipidomics research. The continued development and deployment of new RMs, together with interlaboratory studies and educational outreach and training, will further promote sound QA practices in the community.

Roles of Nitrocompounds in Inhibition of Foodborne Bacteria, Parasites, and Methane Production in Economic Animals

Simple Summary

Supplementation of nitrocompounds in animal diets has been studied to investigate their effects on economic animals. It has been known that nitrocompounds are capable of inhibiting pathogens, parasites, methane and ammonia production. The toxicity, metabolism, and mechanisms of actions have been discussed in the review to conclude the advantages and disadvantages of application of nitrocompounds in animal production.

Abstract

Nitrocompounds are derivatives of hydrocarbons, alcohols, fatty acids, and esters, consisting one or more nitro functional groups. Either natural sources of nitrocompounds or synthetic chemicals have been applied in animal diets to investigate their effects on economic animals, since conjugates of 3-nitropropanol and 3-nitropropionic acid were isolated from Astragalus oblongifolius. In this review, emphasis will be placed on nitrocompounds’ antimicrobial activity, toxicity, metabolisms and mechanisms of actions. Nitrocompounds can be metabolized by ruminal microbials, such as Denitrobacterium detoxificans, or alcohol dehydrogenase in the liver. Moreover, it has been found that nitrocompounds are capable of inhibiting pathogens, parasites, methane and ammonia production; however, overdose of nitrocompounds could cause methemoglobinemia or interfere with energy production in mitochondria by inhibiting succinate dehydrogenase.