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1.
PLoS One ; 15(8): e0235357, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32760112

RESUMO

We evaluated the between-cow (b-cow) variation and repeatability in omasal and milk fatty acids (FA) related to methane (CH4) emission. The dataset was originated from 9 studies with rumen-cannulated dairy cows conducted using either a switch-back or a Latin square design. Production of CH4 per mole of VFA (Y_CH4VFA) was calculated based on VFA stoichiometry. Experiment, diet within experiment, period within experiment, and cow within experiment were considered as random factors. Empirical models were developed between the variables of interest by univariate and bivariate mixed model regression analysis. The variation associated with diet was higher than the b-cow variation with low repeatability (< 0.25) for milk odd- and branch-chain FA (OBCFA). Similarly, for de novo synthesized milk FA, diet variation was ~ 3-fold greater than the b-cow variation; repeatability for these FA was moderate to high (0.34-0.58). Also, for both cis-9 C18:1 and cis-9 cis-12 cis-15 C18:3 diet variation was more than double the b-cow variation, but repeatability was moderate. Among the de novo milk FA, C4:0 was positively related with stoichiometric Y_CH4VFA, while for OBCFA, anteiso C15:0 and C15:0 were negatively related with it. Notably, when analyzing the relationship between omasal FA and milk FA we observed positive intercept estimates for all the OBCFA, which may indicate endogenous post-ruminal synthesis of these FA, most likely in the mammary gland. For milk iso C13:0, iso C15:0, anteiso C15:0, and C15:0 were positively influenced by omasal proportion of their respective FA and by energy balance. In contrast, the concentration of milk C17:0, iso C18:0, C18:0, cis-11 C18:1, and cis-9 cis-12 cis-15 C18:3 were positively influenced by omasal proportion of their respective FA but negatively related to calculated energy balance. Our findings demonstrate that for most milk FA examined, a larger variation is attributed to diet than b-cow differences with low to moderate repeatability. While some milk FA were positively or negatively related with Y_CH4VFA, there was a pronounced effect of calculated energy balance on these estimates. Additionally, even though OBCFA have been indicated as markers of rumen function, our results suggest that endogenous synthesis of these FA may occur, which therefore, may limit the utilization of milk FA as a proxy for CH4 predictions for cows fed the same diet.


Assuntos
Variação Biológica da População , Efeito Estufa , Lactação/fisiologia , Metano/metabolismo , Leite/química , Ração Animal , Animais , Bovinos , Indústria de Laticínios , Conjuntos de Dados como Assunto , Ácidos Graxos/análise , Feminino , Rúmen/metabolismo
2.
Nat Commun ; 11(1): 3941, 2020 08 07.
Artigo em Inglês | MEDLINE | ID: mdl-32770005

RESUMO

Anaerobic oxidation of methane (AOM) mediated by anaerobic methanotrophic archaea (ANME) is the primary process that provides energy to cold seep ecosystems by converting methane into inorganic carbon. Notably, cold seep ecosystems are dominated by highly divergent heterotrophic microorganisms. The role of the AOM process in supporting heterotrophic population remains unknown. We investigate the acetogenic capacity of ANME-2a in a simulated cold seep ecosystem using high-pressure biotechnology, where both AOM activity and acetate production are detected. The production of acetate from methane is confirmed by isotope-labeling experiments. A complete archaeal acetogenesis pathway is identified in the ANME-2a genome, and apparent acetogenic activity of the key enzymes ADP-forming acetate-CoA ligase and acetyl-CoA synthetase is demonstrated. Here, we propose a modified model of carbon cycling in cold seeps: during AOM process, methane can be converted into organic carbon, such as acetate, which further fuels the heterotrophic community in the ecosystem.


Assuntos
Acetatos/metabolismo , Archaea/enzimologia , Proteínas de Bactérias/metabolismo , Coenzima A Ligases/metabolismo , Metano/metabolismo , Anaerobiose , Archaea/genética , Proteínas de Bactérias/genética , Ciclo do Carbono/fisiologia , Coenzima A Ligases/genética , Genoma Arqueal , Sedimentos Geológicos/microbiologia , Redes e Vias Metabólicas/genética , Oxirredução , Água do Mar/microbiologia
3.
PLoS One ; 15(8): e0238057, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32845917

RESUMO

Arthropods are a major soil fauna group, and have the potential to substantially influence the spatial and temporal variability of soil greenhouse gas (GHG) sinks and sources. The overall effect of soil-inhabiting arthropods on soil GHG fluxes still remains poorly quantified since the majority of the available data comes from laboratory experiments, is often controversial, and has been limited to a few species. The main objective of this study was to provide first insights into field-level carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) release of soil-inhabiting larvae of the Scarabaeidae family. Larvae of the genus Melolontha were excavated at various sites in west-central and southern Germany, covering a wide range of different larval developmental stages, larval activity levels, and vegetation types. Excavated larvae were immediately incubated in the field to measure their GHG production. Gaseous carbon release of individual larvae showed a large inter- and intra-site variability which was strongly correlated to larval biomass. This correlation persisted when upscaling individual CO2 and CH4 production to the plot scale. Field release estimates for Melolontha spp. were subsequently upscaled to the European level to derive the first regional GHG release estimates for members of the Scarabaeidae family. Estimates ranged between 10.42 and 409.53 kt CO2 yr-1, and 0.01 and 1.36 kt CH4 yr-1. Larval N2O release was only sporadically observed and not upscaled. For one site, a comparison of field- and laboratory-based GHG production measurements was conducted to assess potential biases introduced by transferring Scarabaeidae larvae to artificial environments. Release strength and variability of captive larvae decreased significantly within two weeks and the correlation between larval biomass and gaseous carbon production disappeared, highlighting the importance of field measurements. Overall, our data show that Scarabaeidae larvae can be significant soil GHG sources and should not be neglected in soil GHG flux research.


Assuntos
Besouros/metabolismo , Gases de Efeito Estufa/análise , Animais , Biomassa , Dióxido de Carbono/análise , Dióxido de Carbono/metabolismo , Besouros/química , Besouros/crescimento & desenvolvimento , Gases de Efeito Estufa/metabolismo , Larva/química , Larva/metabolismo , Metano/análise , Metano/metabolismo , Óxido Nitroso/análise , Óxido Nitroso/metabolismo , Solo/química , Solo/parasitologia
5.
Int J Syst Evol Microbiol ; 70(4): 2499-2508, 2020 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-32559826

RESUMO

An aerobic methane oxidizing bacterium, designated XLMV4T, was isolated from the oxic surface layer of an oil sands tailings pond in Alberta, Canada. Strain XLMV4T is capable of growth on methane and methanol as energy sources. NH4Cl and sodium nitrate are nitrogen sources. Cells are Gram-negative, beige to yellow-pigmented, motile (via a single polar flagellum), short rods 2.0-3.3 µm in length and 1.0-1.6 µm in width. A thick capsule is produced. Surface glycoprotein or cup shape proteins typical of the genera Methylococcus, Methylothermus and Methylomicrobium were not observed. Major isoprenoid quinones are Q-8 and Q-7 at an approximate molar ratio of 71 : 22. Major polar lipids are phosphoglycerol and ornithine lipids. Major fatty acids are C16 : 1 ω8+C16 : 1 ω7 (34 %), C16 : 1 ω5 (16 %), and C18 : 1 ω7 (11 %). Optimum growth is observed at pH 8.0 and 25 °C. The DNA G+C content based on a draft genome sequence is 46.7 mol%. Phylogenetic analysis of 16S rRNA genes and a larger set of conserved genes place strain XLMV4T within the class Gammaproteobacteria and family Methylococcaceae, most closely related to members of the genera Methylomicrobium and Methylobacter (95.0-97.1 % 16S rRNA gene sequence identity). In silico genomic predictions of DNA-DNA hybridization values of strain XLMV4T to the nearest phylogenetic neighbours were all below 26 %. On the basis of the data presented, strain XLMV4T is considered to represent a new genus and species for which the name Methylicorpusculum oleiharenae is proposed. Strain XLMV4T (=DSMZ DSM 27269=ATCC TSD-186) is the type strain.


Assuntos
Methylococcaceae/classificação , Campos de Petróleo e Gás/microbiologia , Filogenia , Tanques/microbiologia , Alberta , Técnicas de Tipagem Bacteriana , Composição de Bases , DNA Bacteriano/genética , Ácidos Graxos/química , Metano/metabolismo , Metanol/metabolismo , Methylococcaceae/isolamento & purificação , Hibridização de Ácido Nucleico , Pigmentação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA , Ubiquinona/química
6.
Ecotoxicol Environ Saf ; 202: 110859, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32574861

RESUMO

The effects of quinoid compounds on azo dyes decolorization were studied. Compared with other quinones, menadione was the most effective at aiding azo dye decolorization. Sodium formate was a suitable carbon source for the anaerobic decolorization system. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis indicated that the microbial structure changed in response to varying carbon sources. Phylogenetic analysis showed that the anaerobic sludge was consisted mainly of nine genera. The mechanism studies showed that the biotransformation of menadione to its hydroquinone form was the rate-limiting step in the dye decolorization process. Moreover, study of the electron transfer mechanism of quinone-mediated reduction showed that azo dye decolorization is not a specific reaction. The NADH chain was involved in the decolorization process. The methane production test indicated that azo dyes had an inhibitory effect on methane production. However, supplementation with a redox mediator could recover the inhibited methanogenesis. High-throughput sequencing analysis revealed that the methanogenic archaeal community was altered in the anaerobic sludge with or without azo dyes and the redox mediator.


Assuntos
Compostos Azo/metabolismo , Quinonas/metabolismo , Eliminação de Resíduos Líquidos , Anaerobiose , Compostos Azo/química , Benzoquinonas , Biotransformação , Catálise , Corantes/química , Metano/metabolismo , Oxirredução , Filogenia , Quinonas/química , Esgotos
7.
Chemosphere ; 259: 127418, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32574848

RESUMO

This work evaluated the effect of different initial biomass ratios in a co-culture of an alkaliphilic methanotrophic bacteria consortium (AMB) and the green microalga Scenedesmus obtusiusculus (GM) on the maximum CH4 specific biodegradation rate and global carbon uptake. The highest maximum specific biodegradation rate was 589 ± 0.01 mgCH4 gbiomass-1 d-1 obtained for a proportion of 3:1 AMB-GM (w w-1) and 8% of initial CH4 in the headspace. The methane degradation rate was 1.5 times lower than the value obtained solely by the AMB consortium, and it was associated with pH increases due to the evolved CO2 consumption by the microalga. Increased activity of the AMB consortium along the experiments was due to progressive adaptation. Massive sequencing revealed the presence of methanotrophic/methylotrophic species such as Methylocystis sp., Methylomicrobium sp., Methylophaga sp., and Hyphomicrobium sp. Successful complete methane and carbon dioxide uptake was obtained with the 3:1, 4:1, and 5:1 AMB-GM biomass ratios, while for the rest of the ratios tested, more than 70% of the initial methane was transformed into biomass and inorganic carbon. This study showed that methanotrophic-microalgal co-cultures lead to a promising strategy for greenhouse gases mitigation in one step.


Assuntos
Biodegradação Ambiental , Gases de Efeito Estufa , Metano/metabolismo , Microalgas/fisiologia , Biomassa , Dióxido de Carbono/metabolismo , Técnicas de Cocultura , Methylocystaceae , Microalgas/metabolismo , Scenedesmus/metabolismo
8.
J Biosci Bioeng ; 130(3): 311-318, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32487498

RESUMO

Methane-oxidizing bacteria (MOB) possess the metabolic potential to assimilate the highly potent greenhouse gas, CH4, and can also synthesize valuable products. Depending on their distinct and fastidious metabolic pathways, MOB are mainly divided into Type I and Type II; the latter are known as producers of polyhydroxyalkanoate (PHA). Despite the metabolic potential of MOB to synthesize PHA, the ecophysiology of MOB, especially under high CH4 flux conditions, is yet to be understood. Therefore, in this study, a rice paddy soil receiving a high CH4 flux from underground was used as an inoculum to enrich MOB using fed-batch operation, then the enriched Type II MOB were characterized. The transitions in the microbial community composition and CH4 oxidation rates were monitored by 16S rRNA gene amplicon sequencing and degree of CH4 consumption. With increasing incubation time, the initially dominant Methylomonas sp., affiliated with Type I MOB, was gradually replaced with Methylocystis sp., Type II MOB, resulting in a maximum CH4 oxidation rate of 1.40 g-CH4/g-biomass/day. The quantification of functional genes encoding methane monooxygenase, pmoA and PHA synthase, phaC, by quantitative PCR revealed concomitant increases in accordance with the Type II MOB enrichment. These increases in the functional genes underscore the significance of Type II MOB to mitigate greenhouse gas emission and produce PHA.


Assuntos
Metano/metabolismo , Methylococcaceae/metabolismo , Oryza/metabolismo , Oryza/microbiologia , Técnicas de Cultura Celular por Lotes , Methylococcaceae/genética , Methylococcaceae/crescimento & desenvolvimento , Microbiota , Oxirredução , Oxigenases/genética , RNA Ribossômico 16S/genética , Solo/química
9.
Anim Sci J ; 91(1): e13392, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32557991

RESUMO

This study evaluated the effects of Allium mongolicum Regel (AM) supplementation on nitrogen (N) balance, ruminal fermentation, and antioxidant properties. Sixteen male calves were assigned randomly to four groups, and the four were added with 0 (CON), 200 mg/kg (body weight; BW) (Low AM; LA), 400 mg/kg (BW) (Middle AM; MA), or 800 mg/kg (BW) (High AM; HA) per day for each individual. AM was added on dry matter (DM) basis. The experiment lasted for 58 days. Supplementation of AM could significantly increase average daily gain, DM digestibility, acid detergent fiber digestibility, and retained N/Intake N. N digestibility and molar proportion of propionate in the MA and HA treatments were higher than that in the CON treatment (p < .05), respectively. AM supplementation significantly increased the molar concentration of total volatile fatty acid in the rumen fluid (p < .05). The ratio of acetate to propionate in the MA and HA groups was lower than that in the CON treatment (p < .05). Furthermore, AM supplementation significantly reduced methane (CH4 ) (p < .05) emissions. AM supplementation significantly increased the activities of superoxide dismutase. The MA group could significantly increase the activities of glutathione peroxidase and decrease the content of malondialdehyde. Our results indicated that AM supplementation could affect the nutrient digestibility, CH4 emission, and antioxidant capacity of Simmental calves.


Assuntos
Allium , Fenômenos Fisiológicos da Nutrição Animal/fisiologia , Antioxidantes/metabolismo , Bovinos/metabolismo , Bovinos/fisiologia , Dieta/veterinária , Suplementos Nutricionais , Digestão , Metano/metabolismo , Animais , China , Fermentação , Malondialdeído/metabolismo , Rúmen/metabolismo , Superóxido Dismutase/metabolismo , Ganho de Peso
10.
Chemosphere ; 252: 126492, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32443260

RESUMO

Four upflow 0.018 m3 biofilters (3 beds), B-ME, B-200, B-500 and B-700, all packed with inorganic materials, were operated at a constant air flow rate of 0.18 m3 h-1 to eliminate methane (CH4), a harmful greenhouse gas (GHG), and styrene (C8H8), a carcinogenic volatile organic compound (VOC). The biofilters were irrigated with 0.001 m3 of recycled nutrient solution (NS) every day (flow rate of 60 × 10-3 m3 h-1). Styrene inlet load (IL) was kept constant in each biofilter. Different CH4-ILs varying in the range of 7-60 gCH4 m-3 h-1 were examined in B-ME (IL of 0 gC8H8 m-3 h-1), B-200 (IL of 9 gC8H8 m-3 h-1), B-500 (IL of 22 gC8H8 m-3 h-1) and B-700 (IL of 32 gC8H8 m-3 h-1). Finally, the effect of C8H8 on the macrokinetic parameters of CH4 biofiltration was studied based on the Michaelis-Menten model. Average C8H8 removal efficiencies (RE) varying between 64 and 100% were obtained at CH4-ILs increasing from 7 to 60 gCH4 m-3 h-1 and for C8H8-ILs range of 0-32 gC8H8 m-3 h-1. More than 90% of C8H8 was removed in the bottom and middle beds of the biofilters. By increasing C8H8-IL from 0 to 32 gC8H8 m-3 h-1, maximal EC in Michaelis-Menten model and macrokinetic saturation constant declined from 311 to 39 g m-3 h-1 and from 19 to 2.3 g m-3, respectively, which confirmed that an uncompetitive inhibition occurred during CH4 biofiltration in the presence of C8H8.


Assuntos
Biodegradação Ambiental , Metano/metabolismo , Estireno/metabolismo , Filtração , Gases de Efeito Estufa
11.
PLoS One ; 15(5): e0233303, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32437419

RESUMO

This study compares thirteen rice-based cropping systems in the coastal part of West Bengal, India in terms of productivity, profitability, energetics, and emissions. Information on the crop management practices of these systems was collected on 60 farms through a questionnaire survey. Rice-bitter gourd system was observed to have the highest system yield (49.88 ± 4.34 tha-1yr-1) followed by rice-potato-ridge gourd (37.78 ± 2.77 tha-1yr-1) and rice-potato-pumpkin (36.84 ± 2.04 tha-1yr-1) systems. The rice-bitter gourd system also recorded the highest benefit:cost ratio (3.92 ± 0.061). The lowest system yield and economics were recorded in the rice-fallow-fallow system. Rice-sunflower system recorded highest specific energy (2.54 ± 0.102 MJkg-1), followed by rice-rice (2.14 ± 0.174 MJkg-1) and rice-fallow-fallow (1.91 ± 0.327 MJkg-1) systems, lowest being observed in the rice-bitter gourd (0.52 ± 0.290 MJkg-1) and rice-pointed gourd (0.52 ± 0.373 MJkg-1) systems. Yield-scaled GHGs (YSGHG) emission was highest (1.265 ± 0.29 t CO2eqt-1 system yield) for rice-fallow-fallow system and was lowest for rice-vegetable systems. To estimate the uncertainty of the YSGHG across different systems under study, Monte-Carlo Simulation was performed. It was observed that there was a 5% probability of recording YSGHG emission > 1.15 t CO2eqt-1 system yield from different cropping systems in the present experiment. Multiple system properties such as productivity, economics, energy, and emission from all rice-based systems taken together, the rice-vegetable system performed consistently well across parameters and may be practised for higher economic returns with judicious and sustainable utilization of resources in the coastal saline tracts of the region.


Assuntos
Produtos Agrícolas/economia , Gases de Efeito Estufa/metabolismo , Oryza/metabolismo , Dióxido de Carbono/metabolismo , Mudança Climática/economia , Simulação por Computador , Produção Agrícola/economia , Produção Agrícola/métodos , Produtos Agrícolas/crescimento & desenvolvimento , Produtos Agrícolas/metabolismo , Índia , Metano/metabolismo , Método de Monte Carlo , Óxido Nitroso/metabolismo , Oryza/crescimento & desenvolvimento , Medição de Risco , Salinidade
12.
Anim Sci J ; 91(1): e13381, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32378296

RESUMO

This experiment was carried out to evaluate the effect of reduced dietary crude protein (CP) levels supplemented with or without exogenous phytase on growing pigs. Six dietary treatments arranged in a 3 × 2 factorial arrangements of 3 CP levels (containing 14%, 16%, and 18% CP) supplemented each with or without 5,000 FTU/g phytase enzyme. Thirty growing pigs (average weight of 17.80 ± 0.10 kg) were allotted to the six dietary treatments in a complete randomized design. The final weight, daily weight gain, and feed conversion ratio (FCR) increased significantly with increasing CP levels. While, phytase supplementation improved (p = .044) FCR in pigs. Total solid and volatile solid content of the slurry were higher (p = .001) in pigs fed 14% and 16% CP diets supplemented with phytase when compared with other treatment groups. Concentration of methane gas emitted was lowest (p = .001) in the slurry of pigs fed 14% CP diet with or without phytase and those fed 16% CP diet with phytase supplementation. In conclusion, reduction in dietary CP levels resulted in reduced weight gain and poor FCR. While, reduced CP with phytase supplementation reduced concentration of methane gas emitted.


Assuntos
6-Fitase , Fenômenos Fisiológicos da Nutrição Animal , Dieta com Restrição de Proteínas , Dieta/veterinária , Proteínas na Dieta/administração & dosagem , Suplementos Nutricionais , Fezes/química , Gases/metabolismo , Metano/metabolismo , Suínos/crescimento & desenvolvimento , Suínos/metabolismo , Animais , Dieta com Restrição de Proteínas/efeitos adversos , Ganho de Peso
13.
Anim Sci J ; 91(1): e13383, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32410280

RESUMO

The objectives of this study were to estimate genetic parameters and to perform a genome-wide association study (GWAS) for predicted methane-related traits in Japanese Black steers. The methane production and yield traits were predicted using on-farm measurable traits, such as dry matter intake and average daily gain. A total of 4,578 Japanese Black steers, which were progenies of 362 sires genotyped with imputed 551,995 single nucleotide polymorphisms (SNPs), had phenotypes of predicted methane-related traits during the total fattening period (52 weeks). For the estimation of genetic parameters, the estimated heritabilities were moderate (ranged from 0.57 to 0.60). In addition, the estimated genetic correlations of methane production traits with most of carcass traits and feed-efficiency traits were unfavorable, but those of methane yield traits were favorable or low. For the GWAS, no genome-wide significant SNP was detected, but a total of four quantitative trait locus (QTL) regions that explained more than 5.0% of genetic variance were localized on the genome, and some candidate genes associated with growth and feed-efficiency traits were located on the regions. Our results suggest that the predicted methane-related traits are heritable and some QTL regions for the traits are localized on the genome in Japanese Black steers.


Assuntos
Fenômenos Fisiológicos da Nutrição Animal/genética , Bovinos/genética , Bovinos/metabolismo , Dieta/veterinária , Estudo de Associação Genômica Ampla/veterinária , Genoma/genética , Metano/metabolismo , Característica Quantitativa Herdável , Animais , Masculino , Fenótipo , Polimorfismo de Nucleotídeo Único
14.
Nat Commun ; 11(1): 1878, 2020 04 20.
Artigo em Inglês | MEDLINE | ID: mdl-32313021

RESUMO

Methane is the second most important greenhouse gas after carbon dioxide and approximately 11% of the global anthropogenic methane emissions originate from rice fields. Sulfate amendment is a mitigation strategy to reduce methane emissions from rice fields because sulfate reducers and methanogens compete for the same substrates. Cable bacteria are filamentous bacteria known to increase sulfate levels via electrogenic sulfide oxidation. Here we show that one-time inoculation of rice-vegetated soil pots with cable bacteria increases the sulfate inventory 5-fold, which leads to the reduction of methane emissions by 93%, compared to control pots lacking cable bacteria. Promoting cable bacteria in rice fields by enrichment or sensible management may thus become a strategy to reduce anthropogenic methane emissions.


Assuntos
Bactérias/metabolismo , Metano/metabolismo , Oryza/metabolismo , Solo/química , Agricultura , Ciclo do Carbono , Mudança Climática , Efeito Estufa , Gases de Efeito Estufa , Concentração de Íons de Hidrogênio , Metano/análise , Microeletrodos , Microbiologia do Solo , Sulfatos/metabolismo
15.
PLoS One ; 15(4): e0231713, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32320412

RESUMO

Deltaic wetlands are highly productive ecosystems, which characteristically can act as C-sinks. However, they are among the most threatened ecosystems, being very vulnerable to global change, and require special attention towards its conservation. Knowing their climate change mitigating potential, conservation measures should also be oriented with a climatic approach, to strengthen their regulatory services. In this work we studied the carbon biogeochemistry and the specific relevance of certain microbial guilds on carbon metabolisms of the three main types of deltaic wetlands located in the Ebro Delta, north-eastern Spain, as well as how they deal with human pressures and climate change effects. We estimated the metabolic rates of the main carbon-related metabolisms (primary production and respiration) and the resulting carbon and global warming potential balances in sites with a different salinity range and trophic status. With the results obtained, we tried to define the influence of possible changes in salinity and trophic level linked to the main impacts currently threatening deltaic wetlands, on the C-metabolisms and GHG emissions, for a better understanding of the mitigating capacity and their possible enhancement when applying specific management actions. Metabolic rates showed a pattern highly influenced by the salinity range and nutrients inputs. Freshwater and brackish wetlands, with higher nutrient inputs from agricultural runoff, showed higher C-capture capacity (around 220-250 g C m-2 y-1), but also higher rates of degradative metabolisms (aerobic respiration and CH4 emissions). Contrastingly, the rates of C-related metabolisms and C-retention of Salicornia-type coastal salt marshes were lower (42 g C m-2 y-1). The study of the microbial metacommunity composition by the16S RNA gene sequencing revealed a significant higher presence of methanogens in the salt marsh, and also higher metabolic potential, where there was significantly more organic matter content in sediment. Salinity inhibition, however, explained the lower respiration rates, both aerobic and anaerobic, and prevented higher rates of methanogenesis despite the major presence of methanogens. Conservation measures for these wetlands would require, overall, maintaining the sediment contributions of the river basin intending to overcome the regression of the Delta and its salt marshes in a climate change scenario. Particularly, for reducing degradative metabolisms, and favour C-retention, nutrient inputs should be controlled in freshwater and brackish wetlands in order to reduce eutrophication. In salt marshes, the reduction of salinity should be avoided to control increases in methanogenesis and CH4 emissions.


Assuntos
Carbono/metabolismo , Chenopodiaceae/metabolismo , Gases de Efeito Estufa/metabolismo , Microbiota/fisiologia , Áreas Alagadas , Agricultura , Dióxido de Carbono , Sequestro de Carbono , Mudança Climática , Metagenoma , Metano/metabolismo , Nutrientes/metabolismo , RNA Ribossômico 16S/genética , Rios , Salinidade , Solo/química , Microbiologia do Solo , Espanha
16.
PLoS One ; 15(4): e0231759, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32330150

RESUMO

Ruminant methane production is a significant energy loss to the animal and major contributor to global greenhouse gas emissions. However, it also seems necessary for effective rumen function, so studies of anti-methanogenic treatments must also consider implications for feed efficiency. Between-animal variation in feed efficiency represents an alternative approach to reducing overall methane emissions intensity. Here we assess the effects of dietary additives designed to reduce methane emissions on the rumen microbiota, and explore relationships with feed efficiency within dietary treatment groups. Seventy-nine finishing steers were offered one of four diets (a forage/concentrate mixture supplemented with nitrate (NIT), lipid (MDDG) or a combination (COMB) compared to the control (CTL)). Rumen fluid samples were collected at the end of a 56 d feed efficiency measurement period. DNA was extracted, multiplexed 16s rRNA libraries sequenced (Illumina MiSeq) and taxonomic profiles were generated. The effect of dietary treatments and feed efficiency (within treatment groups) was conducted both overall (using non-metric multidimensional scaling (NMDS) and diversity indexes) and for individual taxa. Diet affected overall microbial populations but no overall difference in beta-diversity was observed. The relative abundance of Methanobacteriales (Methanobrevibacter and Methanosphaera) increased in MDDG relative to CTL, whilst VadinCA11 (Methanomassiliicoccales) was decreased. Trimethylamine precursors from rapeseed meal (only present in CTL) probably explain the differences in relative abundance of Methanomassiliicoccales. There were no differences in Shannon indexes between nominal low or high feed efficiency groups (expressed as feed conversion ratio or residual feed intake) within treatment groups. Relationships between the relative abundance of individual taxa and feed efficiency measures were observed, but were not consistent across dietary treatments.


Assuntos
Ração Animal , Criação de Animais Domésticos/métodos , Microbioma Gastrointestinal/fisiologia , Efeito Estufa/prevenção & controle , Rúmen/microbiologia , Animais , Bovinos , DNA Bacteriano/isolamento & purificação , Gorduras na Dieta/administração & dosagem , Suplementos Nutricionais , Gases de Efeito Estufa/metabolismo , Masculino , Metano/metabolismo , Methanobacteriaceae/genética , Methanobacteriaceae/isolamento & purificação , Methanobacteriaceae/metabolismo , Methanobacteriales/genética , Methanobacteriales/isolamento & purificação , Methanobacteriales/metabolismo , Methanobrevibacter/genética , Methanobrevibacter/isolamento & purificação , Methanobrevibacter/metabolismo , RNA Ribossômico 16S/genética , Rúmen/efeitos dos fármacos , Escócia
17.
J Dairy Sci ; 103(5): 4863-4873, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32113778

RESUMO

The aim of the present study was to evaluate, through a survey conducted on commercial farms, the global warming potential (GWP) of different lactating cow total mixed rations (TMR) and to identify the best dietary strategies to increase feed efficiency (FE) and reduce enteric CH4 emission. A total of 171 dairy herds were selected: data about dry matter intake (DMI), lactating cow TMR composition, and milk production and composition were provided by farmers. Diet GWP (kg of CO2 equivalents; CO2eq) was calculated as sum of GWP (kg of CO2eq) of each included ingredient, considering inputs needed at field level, feed processing, and transport. For soybean solvent meal, land use change was included in the assessment. Enteric methane production (g/d) was estimated [using the equation CH4 (g/d) = 2.54 + 19.14 × DMI] to calculate CH4 emission for kilograms of fat- and protein-corrected milk (FPCM). The data set was analyzed by generalized linear model and logistic analysis using SAS 9.4 (SAS Institute Inc., Cary, NC). The frequency distribution showed wide variation among farms for GWP (kg of CO2eq) of TMR: approximately 25% of the surveyed farms showed a diet GWP of 15 kg of CO2eq, 20% showed a GWP of 13 kg of CO2eq, and 16.7% showed a GWP of 17 kg of CO2eq. The variation among farms was due to the feedstuffs used. Among feedstuffs, soybean meal (SBM) had the highest correlation with the GWP of the TMR as shown by the following equation: TMR GWP (kg of CO2eq) = 2.49 × kg of SBM + 6.9 (R2 = 0.547). Moreover, diets with inclusion of SBM >15% of dry matter (DM) did not result in higher milk production than diets with a lower inclusion of SBM (≤15%). Average daily milk production of cows was 29.8 [standard deviation (SD) 4.83] kg with fat and protein contents of 3.86% (SD 0.22) and 3.40% (SD 0.14), respectively. The average DMI (kg/d) of lactating cows was 22.3 (SD 2.23). Logistic analysis demonstrated that corn silage ≤30% of diet DM was associated with higher FE. Almost 50% of farms had an average value of 15.0 g of CH4/kg of FPCM and about 30% of farms had an average of 12.5 g of CH4/kg of FPCM. The results demonstrated that lower enteric CH4 production was related to inclusion (% of diet DM) of ≤12% alfalfa hay and >30% corn silage. Diets with >34% neutral detergent fiber had higher CH4 production (>14.0 g/kg of FPCM) than those with lower neutral detergent fiber content. In contrast, lower enteric CH4 production (≤14.0 g/kg of FPCM) was related to diets characterized by net energy of lactation (NEL) >1.61 Mcal/kg and >4% ether extract. The variability in TMR GWP shows significant potential for reducing the GWP of a diet through choice and inclusion levels of ingredients (mainly SBM) and the possibility of decreasing methane enteric emission associated with milk production on a commercial scale.


Assuntos
Ração Animal , Bovinos/metabolismo , Dieta/veterinária , Lactação , Metano/metabolismo , Animais , Feminino , Itália , Leite , Rúmen/metabolismo , Silagem , Soja , Inquéritos e Questionários , Zea mays
18.
Anim Sci J ; 91(1): e13341, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32219938

RESUMO

The objective of this study was to develop a prediction equation for methane-related traits in beef cattle and evaluate this equation using datasets with different cattle breeds and roughage rates. Enteric methane emission (CH4 , l/day) was measured using open-circuit respiration chambers. Dry matter intake (DMI, kg/day), body weight (BW, kg), daily gain (DG, kg), total digestible nutrients (TDN, %DMI), and roughage rate (Rrate, %) were used as independent variables, and methane-related traits-CH4 , CH4 per DMI (CH4 /DMI, l/kg), and methane conversion factor (MCF, %)-were used as dependent variables. The best-fit equations to predict methane-related traits using a total of 76 records were CH4  = -676.7 + 0.04194 × BW + 29.88 × DMI + 7.883 × TDN + 4.367 × Rrate, CH4 /DMI = -52.24 - 1.193 × 10-3  × BW - 5.905 × DG + 1.077 × TDN + 0.5008 × Rrate, and MCF = -11.43 - 5.308 × 10-4  × BW - 1.223 × DG + 0.2336 × TDN + 0.1157 × Rrate. The predictive ability of the developed equations differed between roughage rates but not between breeds. For CH4 , the predictive ability of the developed equations was better compared with previously reported equations in the low roughage rate dataset, but not in the high roughage rate dataset. Our results suggest that the developed equations of methane-related traits can be applied in beef cattle fed with low roughage diets.


Assuntos
Ração Animal , Bovinos/metabolismo , Dieta/veterinária , Fibras na Dieta , Metano/metabolismo , Fenômenos Fisiológicos da Nutrição Animal , Animais , Previsões
19.
Anim Sci J ; 91(1): e13349, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32219970

RESUMO

Rumen fermentation can produce hydrogen sulfide (H2 S), and H2 S can be rapidly absorbed by the intestinal wall in nature. If excessive H2 S was produced in rumen, it might be toxic to ruminants. This article reviews the research progress of toxicity of H2 S, rumen H2 S production pathway and its influential factors to lay a foundation for further research and application of rumen H2 S-producing regulation in ruminant.


Assuntos
Sulfeto de Hidrogênio/metabolismo , Sulfeto de Hidrogênio/toxicidade , Pesquisa , Ruminantes/metabolismo , Animais , Metano/metabolismo
20.
J Dairy Sci ; 103(5): 4367-4377, 2020 May.
Artigo em Inglês | MEDLINE | ID: mdl-32147260

RESUMO

This study aimed to identify interactions between state of lactation (dry or early lactating) and immune responder group (low, medium, or high) for energy metabolism traits as well as metabolic and immunological traits in dairy cows. In early lactation, when the energy priority of cows shifts toward the mammary gland, the energy available to be partitioned toward the immune system may differ among individuals. The equilibrium between energy supply from feed, digestion, and body reserve mobilization and energy expenditure with milk, immune system, methane, and heat production is delicate in this stage. Seventeen Holstein cows entering their second to fifth lactation were kept under comparable feeding, housing, and management conditions and were studied from 14 ± 6 d before calving to 11 ± 3 d after calving. Feed intake, milk yield, body condition, blood metabolites, and cortisol as well as gaseous exchange in respiration chambers were measured. The latter was used to quantify methane emission and to calculate resting metabolic rate and heat production. Subsets of blood leukocytes and peripheral blood mononuclear cells (PBMC) were monitored. Activation and proliferation of the PBMC in response to the mitogen phytohemagglutinin ante- and postpartum were assessed using the oxygen consumption rate (24-h cell culture assay) and the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyl tetrazolium bromide (MTT) assay (72-h cell culture assay). Cows were classified based on the in vitro proliferative response of the PBMC measured postpartum in low (n = 6), medium (n = 5), and high (n = 6) responders. We found no interaction of state of lactation with responder group for feed intake, milk yield, efficiency, metabolic traits, and immune cell activation ante- and postpartum. However, after calving, low-responder cows produced less methane per unit of body weight and per unit of energy-corrected milk compared with the other cows. This might be indicative of a low rumen fermentation intensity. Low responders might therefore suffer from a lower availability of digestible energy in early lactation and not be able to sustain the shift from immune cell activation to proliferation. If so, the selection of environmentally friendly low-methane emitters could promote phenotypes with a compromised immune response in the critical early lactation.


Assuntos
Proliferação de Células , Lactação , Linfócitos/fisiologia , Metano/metabolismo , Animais , Bovinos , Indústria de Laticínios , Feminino
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