Devitalization of Bacteria in Composted Cattle Manure with Natural Additives and Risk for Environment

Nowadays, there is an effort to improve the effectiveness of the composting process, supported by the addition of various supplements to reduce soil nutrition losses and increase soil remediation. The aim of this study was to examine the devitalization effect of natural additives like zeolite-clinoptilolite and its combination with hydrated lime in composted cattle manure on indicator and pathogen bacteria. The composting process was running in three static piles of cattle manure mixed with wheat straw (control, zeolite-lime, and zeolite) for 126 days. Composted manure substrates were determined for physicochemical (temperature, pH, nitrogen and phosphorus content, C/N, organic matter, and moisture) and microbiological analyses (Salmonella spp., indicator bacteria). The effects of additives were reflected in changes in physicochemical factors, e.g., an increase in temperature (<53 °C) or pH (<9.3). According to Pearson correlation, these changes (pH, Nt, Pt) resulted in a significant decrease (p < 0.001) of indicator bacteria (two or three orders) in zeolite pile or zeolite-lime pile. Die-off of Salmonella spp. in the zeolite-lime pile was indicated within 41 days; in other piles, this occurred on day 63. Our results can aid in further optimizing the composting of cattle manure in order to lower environmental pollution and the risk of human infection.

Effects of Antibiotics on the DAMO Process and Microbes in Cattle Manure

Denitrifying anaerobic methane oxidation (DAMO) can mitigate methane emissions; however, this process has not been studied in cattle manure, an important source of methane emissions in animal agriculture. The objective of this study was to investigate the occurrence of DAMO microbes in cattle manure and examine the impacts of veterinary antibiotics on the DAMO process in cattle manure. Results show that DAMO archaea and bacteria consistently occur at high concentrations in beef cattle manure. During the long-term operation of a sequencing batch reactor seeded with beef cattle manure, the DAMO activities intensified, and DAMO microbial biomass increased. Exposure to chlortetracycline at initial concentrations up to 5000 μg L-1 did not inhibit DAMO activities or affect the concentrations of the 16S rRNA gene and functional genes of DAMO microbes. In contrast, exposure to tylosin at initial concentrations of 50 and 500 μg L-1 increased the activities of the DAMO microbes. An initial concentration of 5000 μg L-1 TYL almost entirely halted DAMO activities and reduced the concentrations of DAMO microbes. These results show the occurrence of DAMO microbes in cattle manure and reveal that elevated concentrations of dissolved antibiotics could inhibit the DAMO process, potentially affecting net methane emissions from cattle manure.

Soil-specific responses in the antibiotic resistome of culturable Acinetobacter spp. and other non-fermentative Gram-negative bacteria following experimental manure application

Acinetobacter spp. and other non-fermenting Gram-negative bacteria (NFGNB) represent an important group of opportunistic pathogens due to their propensity for multiple, intrinsic, or acquired antimicrobial resistance (AMR). Antimicrobial resistant bacteria and their genes can spread to the environment through livestock manure. This study investigated the effects of fresh manure from dairy cows under antibiotic prophylaxis on the antibiotic resistome and AMR hosts in microcosms using pasture soil. We specifically focused on culturable Acinetobacter spp. and other NFGNB using CHROMagar Acinetobacter. We conducted two 28-days incubation experiments to simulate natural deposition of fresh manure on pasture soil and evaluated the effects on antibiotic resistance genes (ARGs) and bacterial hosts through shotgun metagenomics. We found that manure application altered the abundance and composition of ARGs and their bacterial hosts, and that the effects depended on the soil source. Manure enriched the antibiotic resistome of bacteria only in the soil where native bacteria had a low abundance of ARGs. Our study highlights the role of native soil bacteria in modulating the consequences of manure deposition on soil and confirms the potential of culturable Acinetobacter spp. and other NFGNB to accumulate AMR in pasture soil receiving fresh manure.

Long-term impacts of conservation pasture management in manuresheds on system-level microbiome and antibiotic resistance genes

Animal manure improves soil fertility and organic carbon, but long-term deposition may contribute to antibiotic resistance genes (ARGs) entering the soil-water environment. Additionally, long-term impacts of applying animal manure to soil on the soil-water microbiome, a crucial factor in soil health and fertility, are not well understood. The aim of this study is to assess: (1) impacts of long-term conservation practices on the distribution of ARGs and microbial dynamics in soil, and runoff; and (2) associations between bacterial taxa, heavy metals, soil health indicators, and ARGs in manures, soils, and surface runoff in a study following 15 years of continuous management. This management strategy consists of two conventional and three conservation systems, all receiving annual poultry litter. High throughput sequencing of the 16S ribosomal RNA was carried out on samples of cattle manure, poultry litter, soil, and runoff collected from each manureshed. In addition, four representative ARGs (intl1, sul1, ermB, and blactx-m-32) were quantified from manures, soil, and runoff using quantitative PCR. Results revealed that conventional practice increased soil ARGs, and microbial diversity compared to conservation systems. Further, ARGs were strongly correlated with each other in cattle manure and soil, but not in runoff. After 15-years of conservation practices, relationships existed between heavy metals and ARGs. In the soil, Cu, Fe and Mn were positively linked to intl1, sul1, and ermB, but trends varied in runoff. These findings were further supported by network analyses that indicated complex co-occurrence patterns between bacteria taxa, ARGs, and physicochemical parameters. Overall, this study provides system-level linkages of microbial communities, ARGs, and physicochemical conditions based on long-term conservation practices at the soil-water-animal nexus.

Digestate from Agricultural Biogas Plants as a Reservoir of Antimicrobials and Antibiotic Resistance Genes-Implications for the Environment

Antimicrobials and antibiotic resistance genes (ARGs) in substrates processed during anaerobic digestion in agricultural biogas plants (BPs) can reach the digestate (_D), which is used as fertilizer. Antimicrobials and ARGs can be transferred to agricultural land, which increases their concentrations in the environment. The concentrations of 13 antibiotics in digestate samples from biogas plants (BPs) were investigated in this study. The abundance of ARGs encoding resistance to beta-lactams, tetracyclines, sulfonamides, fluoroquinolones, macrolide-lincosamide-streptogramin antibiotics, and the integrase genes were determined in the analyzed samples. The presence of cadmium, lead, nickel, chromium, zinc, and mercury was also examined. Antimicrobials were not eliminated during anaerobic digestion. Their concentrations differed in digestates obtained from different substrates and in liquid and solid fractions (ranging from 62.8 ng/g clarithromycin in the solid fraction of sewage sludge digestate to 1555.9 ng/L doxycycline in the liquid fraction of cattle manure digestate). Digestates obtained from plant-based substrates were characterized by high concentrations of ARGs (ranging from 5.73 × 10² copies/g_DcfxA to 2.98 × 10⁹ copies/g_Dsul1). The samples also contained mercury (0.5 mg/kg dry mass (dm)) and zinc (830 mg/kg dm). The results confirmed that digestate is a reservoir of ARGs (5.73 × 10² to 8.89 × 10¹⁰ copies/g_D) and heavy metals (HMs). In addition, high concentrations of integrase genes (10⁵ to 10⁷ copies/g_D) in the samples indicate that mobile genetic elements may be involved in the spread of antibiotic resistance. The study suggested that the risk of soil contamination with antibiotics, HMs, and ARGs is high in farms where digestate is used as fertilizer.

Impact of Swine and Cattle Manure Treatment on the Microbial Composition and Resistome of Soil and Drainage Water

Evaluating potential environmental and clinical impacts of industrial antibiotic use is critical in mitigating the spread of antimicrobial resistance. Using soil columns to simulate field application of swine or cattle manure and subsequent rain events, and a targeted qPCR-based approach, we tracked resistance genes from source manures and identified important differences in antimicrobial resistance gene transport and enrichment over time in the soil and water of artificially drained cropland. The source manures had distinct microbial community and resistance gene profiles, and these differences were also reflected in the soil columns after manure application. Antibiotic resistance genes (ARGs) were only significantly enriched in effluent samples following the first rain event (day 11) for both soil types compared to the control columns, illustrating the high background level of resistance present in the control soils chosen. For swine, the genes tetQ, tet(36), tet44, tetM, sul2 and ant(6)-ib persisted in the soil columns, whereas tetO, strB and sul1 persisted in effluent samples. Conversely, for cattle manure sul2 and strB persisted in both soil and effluent. The distinct temporal dynamics of ARG distribution between soil and effluent water for each manure type can be used to inform potential mitigation strategies in the future.

Horizontal Gene Transfer of an IncP1 Plasmid to Soil Bacterial Community Introduced by Escherichia coli through Manure Amendment in Soil Microcosms

The quantification and identification of new plasmid-acquiring bacteria in representative mating conditions is critical to characterize the risk of horizontal gene transfer in the environment. This study aimed to quantify conjugation events resulting from manure application to soils and identify the transconjugants resulting from these events. Conjugation was quantified at multiple time points by plating and flow cytometry, and the transconjugants were recovered by fluorescence-activated cell sorting and identified by 16S rRNA sequencing. Overall, transconjugants were only observed within the first 4 days after manure application and at values close to the detection limits of this experimental system (1.00-2.49 log CFU/g of manured soil, ranging between 10^-5 and 10^-4 transconjugants-to-donor ratios). In the pool of recovered transconjugants, we found amplicon sequence variants (ASVs) of genera whose origin was traced to soils (Bacillus and Nocardioides) and manure (Comamonas and Rahnella). This work showed that gene transfer from fecal to soil bacteria occurred despite the less-than-optimal conditions faced by manure bacteria when transferred to soils, but these events were rare, mainly happened shortly after manure application, and the plasmid did not colonize the soil community. This study provides important information to determine the risks of AMR spread via manure application.

Impacts of different treatment methods for cattle manure on the spread of faecal indicator organisms from soil to lettuce in Nigeria

AIM

This study investigated impacts of different organic waste treatment methods on reduction and spread of faecal indicator organisms to food crops in a developing country.

METHODS AND RESULTS

Fresh cattle manure was subjected to three different treatments; anaerobic digestion, burning and composting. Escherichia coli, coliforms and nitrogen content of cattle manure were measured before and after treatment in the amended soil and harvested lettuce. All treatments significantly reduced E. coli and coliform counts but differed in the ratio of E. coli or coliforms to nitrogen. Application of the recommended nitrogen dose of 120 kg ha-1 as bioslurry resulted in significantly lower E. coli and coliform contamination of soil than the same nitrogen rate applied as compost or ash. The E. coli content of lettuces grown on soil amended with treated wastes at recommended rates did not differ between treatments but was significantly lower than in lettuces grown on soil amended with untreated manure.

CONCLUSIONS

Treatment of manure before use as an organic fertilizer significantly reduces potential contamination of both soil and food crops with E. coli and coliforms. To best reduce the spread of E. coli from organic fertilizers, manures should be treated by anaerobic digestion.

SIGNIFICANCE AND IMPACT OF THE STUDY

Information from this study quantifies potential risks associated with use of manures in growing food crops by determining the ratio between pathogen content and required nitrogen application rate.

[Distribution Characteristics of Antibiotics and Antibiotic Resistance Genes in Manure and Surrounding Soil of Cattle Farms in Ningxia]

Livestock breeding intensively uses veterinary antibiotics in concentrated feeding operations to improve growth and control disease. Consequently, livestock and poultry manure is an important repository of antibiotics and antibiotic resistance genes (ARGs). To understanding the distribution of antibiotics and ARGs in manure and surrounding soils of cattle farms in Ningxia, cattle manure from five breeding periods (lactation, calving, growing, pre-fattening, and post-fattening periods) and comparative soil samples were collected from the largest beef-breeding area in Ningxia. The compositions of ARGs in the samples were analyzed by UPLC-MS/MS and HT-qPCR. The results showed that:① Tetracycline, quinolone, and sulfonamide were the dominant antibiotics in cattle manure. The content of antibiotics in the manure varied greatly between different breeding periods. High amounts of antibiotics were detected during the pre-fattening and lactation periods, and the lowest amounts were detected during the calving period. ② Quinolone and tetracycline were the dominant antibiotics in the soils, and the detection rate and content of quinolone were highest. The cattle farms did not affect the distribution of antibiotics in the surrounding soils. The content of quinolone and tetracycline in the soils with cattle manure application were significantly higher than control and surrounding soils. ③ We detected 79-142 ARGs in cattle manure, with aminoglycosides the most common form. The number and relative abundance of ARGs were highest during the growing period and lowest during the calving period. The dominant ARGs were tetQ, ermF, and tetO-01 across all the breeding periods. ④ There were 35-79 ARGs in the tested soils, and multidrug and aminoglycoside ARGs were dominant. The cattle farms did not affect the number and relative abundance of ARGs in the surrounding soils; however, manure application significantly affected the number and relative abundance of ARGs. ⑤ Sulfonamide and chloramphenicol ARGs are at risk of mobilization and horizontal transport. A correlation analysis showed that the relative abundances of aminoglycoside and tetracycline in cattle manure were significantly positively correlated with their contents. ⑥ Aminoglycoside, sulfonamide, chloramphenicol, and mobile genetic elements (MGEs) in manure were significantly or extremely significantly positively correlated with aminoglycosides and sulfonamides in the soils, whereas macrolides were negatively correlated with vancomycin. These results provide baseline data to inform controls on the variety and dosages of feed and veterinary drugs in cattle farms and the application of organic fertilizers in agriculture.

Presence of Antibiotic Residues and Antibiotic Resistant Bacteria in Cattle Manure Intended for Fertilization of Agricultural Fields: A One Health Perspective

Antibiotic resistant bacteria and antibiotic residues can enter the environment when using animal manure as fertilizer. Twenty-five mixed beef cattle farmyard manure samples and 9 mixed fattening calf slurry samples from different farms across Belgium were investigated for the presence of 69 antibiotic residues, antibiotic resistant Escherichia coli and Salmonella spp. Doxycycline, oxytetracycline, ciprofloxacin, enrofloxacin, flumequine and lincomycin were detected in all fattening calf slurry samples with mean concentrations of 2776, 4078, 48, 31, 536 and 36 µg/kg manure, respectively. Sulfadiazine was detected at a mean concentration of 10,895 µg/kg. Further, antibiotic residues were found in only 4 of the 25 beef cattle farmyard manure samples. Oxytetracycline was detected twice below 500 µg/kg. Paromomycin, ciprofloxacin and enrofloxacin were detected in a concentration below 100 µg/kg. Of E. coli isolates, 88% and 23% from fattening calf slurry and beef cattle farmyard manure, respectively, were resistant to at least one of the antibiotics tested. Multi-drug resistance was observed at a maximum of 10 and 7 antibiotics, respectively. The occurrence of antibiotic resistant E. coli and antibiotic residues is shown to be higher in fattening calf slurry than in beef cattle farmyard manure used for agricultural field fertilization.

[Characteristics of heavy metals and bacterial community in manure and surrounding soil of cattle farm in Xiji, Ningxia, China]

To understand the contamination status of heavy metals and bacterial community in the manure and surrounding soils of cattle farm in Ningxia, we collected cattle manure at different breeding periods (lactation, calf, growing, pre-fattening and post-fattening periods) and soil samples from the largest beef breeding area in the region by different distances, with the waste land far away as control. We measured heavy metal contents and the composition and diversity of bacterial community in manure and soil samples. The results showed that: 1) The contents of Cu, Zn, Cd, Pb and Hg in cattle manure were 33.8%-95.8% lower than the national average, while As content was 94.7% higher than the national average. During the breeding periods, the change tendencies of seven kinds of heavy metals in cattle manure were different. The contents of Cu, Cd, Hg and Cr of cattle manure in the pre-fattening period were the highest across all periods. The comprehensive pollution index of heavy metals in pre-fattening and post-fattening periods of cattle manure was highest in all periods. 2) The contents of Cu and Zn in the soils with cattle manure application were higher than control, and the content of Zn were significantly higher than surrounding soil samples. All single and comprehensive soil pollution indices of soil were safe. 3) During the breeding periods, Sequence, OTU and Chao1 index of cattle manure had no specific change. Sequence, OTU and Chao1 of soil with cattle manure application were higher than the soil around the farm. 4) The types of dominant phylum were less in the manure. The relative abundance of Firmicutes was the highest, followed by Bacteroidetes and Proteobacteria. The relative abundance of Firmicutes in the growing period was significantly lower than other breeding periods, and that of other phylum had little variation among periods. The cattle farm did not affect bacterial community in the surrounding soil. The cattle manure application didn't change the relative abundance of bacteria at the phyla level. The abundance of Gp, Gemmatimona, Lysobacte, Subdivision3_genera_incertae_sedis were significantly higher than control and surrounding soil. 5) Organic matter, pH, EC, total nitrogen, total potas-sium, Cd and As significantly affected bacterial diversity and component abundance in cattle manure. Soil pH, total phosphorus and Hg significantly influenced soil bacterial diversity and component abundance. On the whole, the effects of physicochemical properties in cattle manure and soil on bacterial community were more significant than heavy metals. Our results could provide scientific basis for selecting the variety and dosage of feed and veterinary drugs in local cattle farms, as well as the rational application of organic fertilizers.

Cattle Manure Trade Network Analysis and the Relevant Spatial Pathways in an Endemic Area of Foot and Mouth Disease in Northern Thailand

Animal movement is one of the most important risk factors for outbreaks of foot and mouth disease (FMD) in cattle. Likewise, FMD can spread to cattle farms via vehicles contaminated with the FMD virus. In Northern Thailand, the movement of manure transport vehicles and the circulation of manure bags among cattle farms are considered as potential risk factors for FMD outbreaks among cattle farms. This study aimed to determine the characteristics and movement patterns of manure tradesman using social network analysis. A structured questionnaire was used to identify sequences of farms routinely visited by each tradesman. A total of 611 participants were interviewed, including 154 beef farmers, 407 dairy farmers, 36 tradesmen, and 14 final purchasers. A static weighted directed one-mode network was constructed, and the network metrics were measured. For the manure tradesman–cattle farmer network, the tradesman possessed the highest value of in- and out-degree centralities (71 and 4), betweenness centralities (114.5), and k-core values (2). These results indicated that the tradesman had a high frequency of farm visits and had a remarkable influence on other persons (nodes) in the network. The movement of vehicles ranged from within local districts, among districts, or even across provinces. Unclean manure plastic bags were circulated among cattle farms. Therefore, both vehicles and the bags may act as a disease fomite. Interestingly, no recording system was implemented for the movement of manure transport vehicles. This study suggested that the relevant authority and stakeholders should be aware of the risk of FMD spreading within this manure trading network. The findings from this study can be used as supporting data that can be used for enhancing FMD control measures, especially for FMD endemic areas.

Effects of Sulfamethoxazole on the Microbial Community Dynamics During the Anaerobic Digestion Process

Anaerobic digestion (AD) treatment of cattle manure and slurry makes it possible to produce biogas, a renewable and storable biofuel, as well as digestate, a residual organic matter that can be used to replace chemical fertilizers. On the other hand, the intense use of antibiotics (e.g., sulfamethoxazole) in animal husbandry practices is showing increasing negative impacts resulting from the release of still metabolically active molecules into agroecosystems. In the present study, cattle manure collected from an AD plant-feeding tank was used as feedstock for AD experiments in which some batches were spiked with 5 mg L^-1 of sulfamethoxazole (SMX). Adding the antibiotic affected the microbial community dynamic; in particular, the efficiency of the acidogenic and acetogenic phases of the process corresponded to higher CH₄ and H₂ production than in the control. SMX was also degraded, and at the end of the experiment (69 days), just 20% of its initial concentration was found. The relative abundance (ARG/16S) of resistance genes sul1, sul2, and the proxy intI1 initially found in the ingestate decreased during the AD in both the spiked and control batches, suggesting that this process lowers the likelihood of antibiotic resistance genes spreading.

Treatment of Cattle Manure by Anaerobic Co-Digestion with Food Waste and Pig Manure: Methane Yield and Synergistic Effect

The management of cattle manure (CM) has become increasingly challenging because its production continues to rise, while the regulations on manure management have become increasingly stringent. In Korea, most farms produce CM as a dry mixture with lignocellulosic bedding materials (mainly sawdust), making it impractical to treat CM by anaerobic digestion. To address this problem, this study examined whether anaerobic co-digestion with food waste (FW) and pig manure (PM) could be an effective approach for the treatment of CM. The batch anaerobic digestion tests at different CM: FW: PM mixing ratios showed that more methane was produced as the FW fraction increased, and as the CM fraction decreased. The response surface models describing how the substrate mixing ratio affects the methane yield and synergistic effect (methane yield basis) were successfully generated. The models proved that the methane yield and synergistic effect respond differently to changes in the substrate mixing ratio. The maximum 30-day methane yield was predicted at 100% FW, whereas the maximum 30-day synergy index was estimated for the mixture of 47% CM, 6% FW, and 47% PM (total solids basis). The synergy index model showed that CM, FW, and PM could be co-digested without a substantial loss of their methane potential at any mixing ratio (30-day synergy index, 0.89-1.22), and that a possible antagonistic effect could be avoided by keeping the FW proportion less than 50%. The results suggest that co-digestion with PM and FW could be flexibly applied for the treatment and valorization of CM in existing anaerobic digestion plants treating FW and PM.

The Influence of Pressure-Swing Conditioning Pre-Treatment of Cattle Manure on Methane Production

Cattle manure is an agricultural residue, which could be used as source to produce methane in order to substitute fossil fuels. Nevertheless, in practice the handling of this slowly degradable substrate during anaerobic digestion is challenging. In this study, the influence of the pre-treatment of cattle manure with pressure-swing conditioning (PSC) on the methane production was investigated. Six variants of PSC (combinations of duration 5 min, 30 min, 60 min and temperature 160 °C, 190 °C) were examined with regards to methane yield in batch tests. PSC of cattle manure showed a significant increase up to 109% in the methane yield compared to the untreated sample. Kinetic calculations proved also an enhancement of the degradation speed. One PSC-variant (190 °C/30 min) and untreated cattle manure were chosen for comparative fermentation tests in continuously stirred tank reactors (CSTR) in lab-scale with duplicates. In the continuous test a biogas production of 428 mL/g volatile solids (VS) (54.2% methane) for untreated manure was observed and of 456 mL/g VS (53.7% methane) for PSC-cattle-manure (190 °C/30 min). Significant tests were conducted for methane yields of all fermentation tests. Furthermore, other parameters such as furfural were investigated and discussed.

Modelling methane emission mitigation by anaerobic digestion: effect of storage conditions and co-digestion

In this work the methane conversion factor (MCF) of untreated and anaerobically digested cattle manure (CM) as a function of storage temperature, time and co-digestion was measured in an in vitro experiment and modelled based on IPCC (2006) methodology (Tier 2). For this, one sample of untreated CM, one sample of mono-digested CM and three samples of CM co-digested with grass were incubated at seven different temperatures (from 5°C to 50°C) over 346 days. The main results showed that ultimate methane yield (B₀) of CM is higher than the B₀ reported by the IPCC (2006). Two temperature ranges should be considered for MCF evolution, below 15°C very low MCF was measured in this work for untreated CM, mono and co-digested samples. At higher temperatures, MCF obtained in this work and that provided by the IPCC could be comparable depending on storage time. Anaerobic mono-digestion decreased MCF compared to untreated CM at all temperatures and times, except in the temperature range between 20°C and 25°C if storage time is low, due to a lag phase observed in CM. This lag phase would probably not happen in real storage conditions depending on the proportion of old manure remaining in the storage tank. Co-digestion with grass-decreased MCF compared to mono-digestion, but increased CH₄ production in terms of fresh matter due to the higher B₀ of the mixture. Storage time, temperature and co-digestion should be considered in the quantification of CH₄ emission from digested material.

Two-stage thermophilic anaerobic co-digestion of corn stover and cattle manure to enhance biomethane production

Two-stage thermophilic anaerobic co-digestion of cattle manure and corn stover was conducted to increase biomethane production. The first stage pre-digestion of corn stover was studied based on the following treatment variables: corn stover to liquid fraction of digestate (CS:LFD) ratio (1:7, 1:10, 1:13, 1:14), digestion temperature (55 °C, 60 °C) and digestion time (3, 7, 14 days). The reduction in lignin, cellulose and hemicellulose (LCH) was between 3.97% and 11.98%, which increased the biodegradability of corn stover. Corn stover pre-digested with a CS:LFD ratio of 1:10 at 55 °C for a period of 3 and 7 days was subjected to anaerobic co-digestion with cattle manure. The highest biomethane yield was observed on day 21 with a value of 357.41 mL/g volatile solids (VS) for untreated corn stover, 446.84 mL/g VS for corn stover pre-digested for 3 days and 518.58 mL/g VS for corn stover pre-digested for 7 days with LFD. The VS conversion efficiency for co-digestion of cattle manure with untreated corn stover, corn stover pre-digested for 3 days and 7 days was 42.8%, 43.3% and 51.8%, respectively, on day 21, which was higher than that (34.0%) of cattle manure only.

Quantification of volatile fatty acids from cattle manure via non-catalytic esterification for odour indication

This report proposes a new approach to evaluate the odour nuisance of cattle manure samples from three different cattle breeds (i.e., native cattle, beef cattle, and milk cow) by means of quantification and speciation of volatile fatty acids (VFAs). To this end, non-catalytic esterification thermally induced in the presence of a porous material (silica) was undertaken, and the optimal operational parameters such as the derivatizing temperature (330°C) for the maximum yield (≥99±0.4%) of volatile fatty acid methyl esters (VFAMEs) were established. Among the VFA species in cattle manure based on quantification of VFAs, the major species were acetic, butyric and valeric acid. Considering the odour threshold of each VFA, our experimental results suggested that the major contributors to odour nuisance were C_4-5 VFA species (i.e., butyric and valeric acid). Hydrothermal treatment was performed at 150°C for 0-40min to correlate the formation of VFAs with different types of cattle feed formulations. Our experimental data demonstrated that the formation of total VFAs is linearly proportional to the hydrothermal treatment duration and the total content of VFAs in native cattle, beef cattle, and milk cow manure samples reached up to ~1000, ~3200, and ~2800ppm, respectively. Thus, this study demonstrated that the degree of VFA formation is highly dependent on cattle feed formulations, which rely significantly on the protein content. Furthermore, the hydrothermal treatment provides a favourable condition for generating more VFAs. In this context, producing cattle manure into refused derived fuel (RDF) via a hydrothermal treatment is not a viable option to control odour.

Prevalence of Escherichia coli O157:H7 From House Flies (Diptera: Muscidae) and Dairy Samples in North Central Florida1

La detección de Escherichia coli O157:H7 en las lecherías es importante para mejorar la seguridad de los productos lácteos, y se ha llevado a cabo principalmente mediante el aislamiento de las bacterias a partir de las muestras de estiércol. Sin embargo, los componentes biliares presentes en el estiércol complica la identificación genética utilizando la técnica del PCR, y el aislamiento microbiológico se dificulta por la presencia de bacterias competidoras que comparten características microbiológicas similares. El aislamiento de E. coli O157:H7 a partir de la mosca doméstica evita las dificultades asociadas con el estiércol del ganado. El aislamiento de patógenos a partir de las moscas domésticas proporciona información adicional sobre el potencial impacto epidemiológico de la dispersión de la mosca doméstica en la distribución de patógenos, ya que las moscas domésticas se dispersan desde las lecherías donde la E. coli O157:H7 existe en forma endémica en el ganado. En este estudio, se encontró que las moscas domésticas son 2,6 veces más sensibles para la detección de E. coli O157:H7 en las lecherías. Las moscas son más fáciles de capturar y manejar que el estiércol, y deberían ser utilizadas en cualquier ensayo para detectar E. coli O157:H7 en las lecherías y otros establecimientos.

Contrasting Effects of Cattle Manure Applications and Root-Induced Changes on Heavy Metal Dynamics in the Rhizosphere of Soybean in an Acidic Haplic Fluvisol: A Chronological Pot Experiment

To characterize the dynamic mobilization of heavy metals (HM) in a crop-soil system affected by cattle manure (CM) application, soybean [Glycine max L. Merr. cv. Toyoharuka] crops were exposed in a chronological pot experiment to three CM application rates and sampled at two vegetative stages and two reproductive stages. A sequential extraction procedure for metal fractionation, soil pH, microbial activity, and plant HM uptake was determined. In non-rhizopshere soil, with CM application a liming effect was detected, and increased microbial activity was detected at the reproductive stage. CM application shifted Cd from available state to oxide-bound pool in non-rhizosphere soil; however, shifts in Cd from an oxide-bound pool to the available state were observed in rhizosphere soil. CM application stabilized the available Zn and Pb to oxide-bound Zn and organic-bound Pb in both non-rhizosphere and rhizosphere soils, and the stabilizing degree increased with higher CM application rates. The promoted Zn immobilization in the rhizosphere was due to the liming effects induced by added CM that counteracted the root-induced acidification. On the basis of a stepwise multiple regression analysis, the shift of Cd and Pb fractionation was mainly related to microbial activity. Adding manure inhibited Zn and Pb uptake but promoted Cd uptake by soybean, and a greater influence was detected at the reproductive stage, at which CM application increased the root Cd-absorbing power but did not significantly affect the Zn- and Pb-absorbing powers. In an agricultural context, long-term CM application, even at the recommended rate of 10.13 Mg ha-1, may cause a soybean Zn deficiency and high Pb accumulation in Haplic Fluvisols, although CM is often considered as an environmentally friendly fertilizer.

Influence of the ultrasound pretreatment on anaerobic digestion of cattle manure, food waste and crude glycerine

To increase the production of methane, when cattle manure (CM) is digested, pretreatments can be applied and/or the manure can be co-digested with other wastes. In this research work, a mixture of CM, food waste (FW) and raw glycerine (Gly) in a proportion in weight of 87% CM, 10% FW and 3% Gly was digested, (a) without pretreatment and (b) with pretreatment by ultrasound, applying a sonication energy of 1040 kJ/kg total solids. Specific methane production was 290 L CH₄/kg volatile solids (VS) without pretreatment and 520 L CH₄/kg VS with pretreatment. With respect to the volumetric methane production, 1.07 L CH₄/L_reactor.day was produced in the first case, and in the second case, 1.98 L CH₄/L_reactor.day. We can conclude that the application of ultrasound pretreatment significantly improved the production of biogas.

Modelling anaerobic digestion in an industrial biogas digester: Application of lactate-including ADM1 model (Part II)

A modified Anaerobic Digestion Model No. 1 (ADM1xp) including lactate was applied to a full-scale biogas plant. This model considers monosaccharides to degrade through lactic acid, which further degrades majorly into acetate followed by propionate and butyrate. Experimental data were derived from the previous works in the same laboratory, and the proposed parameters were validated against batch experiments. After successful validation, the biogas plant bearing a fermenter size of 7 dam³ and operated with food waste and cattle manure was simulated. The biogas production and methane content were reliably simulated, and a good fit could be obtained against the experimental data with an average difference of less than 1%. When compared to the original ADM1 model, the performance of the lactate-incorporated model was found to be improved. Inclusion of lactate as a parameter in the ADM1xp model is recommended for an increased sensitivity and enhanced prediction principally for systems dealing with high carbohydrate and lactate loads.

An Overview of the Control of Bacterial Pathogens in Cattle Manure

Cattle manure harbors microbial constituents that make it a potential source of pollution in the environment and infections in humans. Knowledge of, and microbial assessment of, manure is crucial in a bid to prevent public health and environmental hazards through the development of better management practices and policies that should govern manure handling. Physical, chemical and biological methods to reduce pathogen population in manure do exist, but are faced with challenges such as cost, odor pollution, green house gas emission, etc. Consequently, anaerobic digestion of animal manure is currently one of the most widely used treatment method that can help to salvage the above-mentioned adverse effects and in addition, produces biogas that can serve as an alternative/complementary source of energy. However, this method has to be monitored closely as it could be fraught with challenges during operation, caused by the inherent characteristics of the manure. In addition, to further reduce bacterial pathogens to a significant level, anaerobic digestion can be combined with other methods such as thermal, aerobic and physical methods. In this paper, we review the bacterial composition of cattle manure as well as methods engaged in the control of pathogenic microbes present in manure and recommendations that need to be respected and implemented in order to prevent microbial contamination of the environment, animals and humans.

Characterization of tet(Y)-carrying LowGC plasmids exogenously captured from cow manure at a conventional dairy farm

Manure from dairy farms has been shown to contain diverse tetracycline resistance genes that are transferable to soil. Here, we focus on conjugative plasmids that may spread tetracycline resistance at a conventional dairy farm. We performed exogenous plasmid isolation from cattle feces using chlortetracycline for transconjugant selection. The transconjugants obtained harbored LowGC-type plasmids and tet(Y). A representative plasmid (pFK2-7) was fully sequenced and this was compared with previously described LowGC plasmids from piggery manure-treated soil and a GenBank record from Acinetobacter nosocomialis that we also identified as a LowGC plasmid. The pFK2-7 plasmid had the conservative backbone typical of LowGC plasmids, though this region was interrupted with an insert containing the tet(Y)-tet(R) tetracycline resistance genes and the strA-strB streptomycin resistance genes. Despite Acinetobacter populations being considered natural hosts of LowGC plasmids, these plasmids were not found in three Acinetobacter isolates from the study farm. The isolates harbored tet(Y)-tet(R) genes in identical genetic surroundings as pFK2-7, however, suggesting genetic exchange between Acinetobacter and LowGC plasmids. Abundance of LowGC plasmids and tet(Y) was correlated in manure and soil samples from the farm, indicating that LowGC plasmids may be involved in the spread of tet(Y) in the environment.

Emission and control of N2O and composition of ash derived from cattle manure combustion using a pilot-scale fluidized bed incinerator

This study investigates the emission of nitrous oxide (N₂O) and discusses the reduction of N₂O emissions during the 24-h combustion of cattle manure using a pilot-scale fluidized bed incinerator under various experimental conditions. The results of these experiments were then validated against previously reported data. In addition, the characteristics of cattle manure incineration ash and their changes under different combustion conditions were estimated. In incineration experiments with composted cattle manure, N₂O concentrations using multi-stage combustion were 75% lower than the concentrations resulting from normal combustion without additional auxiliary fuel, since N₂O could be decomposed in the high-temperature zone formed by the inlet of the secondary combustion air. The N₂O emission factor under normal combustion conditions (800°C) was 6.0% g-N₂O-N/g-N. This result is similar to the values found in previous studies at the same temperature. The N₂O emission factor was decreased to 1.6% g-N₂O-N/g-N using a multi-stage combustion procedure. The current Japanese N₂O emission factor of 0.1% g-N₂O-N/g-N is an underestimate for some conditions and should be uniquely specified for each condition. Finally, cattle manure ash contains ample fertilizer elements, little Fe, Al and Zn, but abundant Cl. Therefore if Cl could be removed by some kind of pretreatment, cattle manure ash could be used as a favourable fertilizer.

Assessment of a composting process for the treatment of beef cattle manure

The intensive breeding of beef cattle in Juncosa de les Garrigues (Catalonia, Spain) leads to the production of a large volume of manure that needs appropriate management. Land application in the area at agronomic rates is not enough to ensure good management practices, making necessary extended on-farm storage and the export of part of the production to long distances. In this context, the implementation of a collective treatment based on composting could help in enhancing the handling of manure. We assessed a full-scale composting process based on turned windrows (W), and involving treatment of beef cattle manure (CM) alone (two typologies were considered according to carbon-to-nitrogen ratios of ~25 (CM1, W1) and ~14 (CM2, W2)), or mixed with bulking agent (CM2/BA, W3) and dewatered digested sewage sludge (CM2/BA/DDSS, W4). Composting significantly improved the transportability of nutrients (final volumes were 40-54% of the initial volume). Temperature >55°C was reached in all the treatments but following different time patterns. Under the applied conditions of turning and rewetting, 14 weeks of processing did not ensure the production of stable, and mature, compost. Thus, only compost from W1 attained the maximum degree of stability as well as concentration of ammonium-N < 0.01% (with ammonium-N/nitrate-N ratio of 0.2) and low phytotoxicity. However, high pH, salinity, and heavy metal contents (Cu and Zn) may limit its final use. Addition of BA was advised to be kept to minimum, whereas use of DDSS as a co-substrate was not recommended in agreement to the higher loss of N and levels of heavy metals in the final compost.

The influence of earthworms on nutrient dynamics during the process of vermicomposting

In the present study the potential of the earthworm Eisenia andrei to modify chemical and microbiological properties, with a special focus on the nutrient content of fresh organic matter, was evaluated during 16 weeks of vermicomposting of cattle manure and sewage sludge. Samples were periodically collected in order to determine the changes in inorganic nitrogen (N), in total microbial biomass and activity, as well as in the total and available content of macro- and micronutrients. An optimal moisture level, ranging from 75% to 88%, was maintained throughout the process. The content of organic matter decreased over time, but no changes were found in this parameter as a result of earthworm activity. The carbon/N ratio rapidly decreased, but only in the manure, reflecting rapid decomposition and mineralisation of the organic matter by the earthworms. An increase in N mineralisation was also attributable to the presence of earthworms, although in the manure this effect was hardly detectable before the eighth week of vermicomposting. Earthworm activity also enhanced the total content of potassium, calcium and iron together with an increase in the availability of phosphorus and zinc. We did not detect a significant earthworm effect on microbial respiration, but their activity increased greatly microbial biomass nitrogen in sewage sludge.