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Bedding materials are aimed at providing a safe and comfortable resting environment for cows. Control of pathogen proliferation in these substrates is crucial to prevent intramammary infections in dairy cows, as these can significantly impact milk quality, cow health, and farm productivity. This is particularly relevant in the case of organic bedding substrates, including manure-derived materials. This study aimed to evaluate the in vitro effect of a lime-based conditioner (LBC), composed of CaCO3MgCO3 and Ca(OH) 2 * Mg(OH)2, at increasing concentrations on the physical-chemical characteristics and bacterial counts of untreated anaerobically digested manure solids (ADMS) and separated raw manure solids (SRMS). Unused ADMS and SRMS were evaluated at four LBC weight-based concentrations: 0 (as untreated control), 10, 15, and 20% of LBC inclusion. The bedding materials were assessed immediately after LBC addition (0 h) and after 24, 72, and 168 h of storage at 28°C. The dry matter content (DM), and pH were measured for all the time points. Standard microbiological methods were used to assess total bacterial counts (TBC), other Gram-negative bacteria, coliforms, Escherichia coli, and streptococci and streptococci-like organism (SSLO). It was observed a linear increase in both DM and pH with increasing concentrations of LBC. Specifically, for each percentage unit increase of LBC, the DM of ADMS and SRMS increased by 0.73 and 0.71%, respectively. Similarly, for each percentage unit of LBC, the pH of ADMS and SRMS increased by 0.15 and 0.19, respectively. Conversely, a linear decrease in TBC, Gram-negative bacteria, coliforms, E. coli, and SSLO was observed with increasing concentrations of the LBC. Manure-derived materials without the inclusion of the LBC had bacterial counts that tended to remain high or increase over time. Otherwise, bedding materials with LBC application had reduced bacterial counts. Based on the results of the present study, it was observed that the higher the concentration of LBC, the more significant the reduction of bacterial counts. Specifically, bacterial recovery was lower when higher concentrations of LBC were applied. Our findings underscore the potential of LBC in effectively controlling environmental bacteria and improving the physical-chemical characteristics of manure-derived bedding materials to improve cow health and welfare.

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Covered anaerobic lagoons (CALs) are Latin America's main livestock waste treatment systems. Mexico has 680 CALs that present low biogas yields (0.05 m3 m-3 digester d-1) and low COD removal rates (< 60%). This work focused on diagnosing CAL´s low performance in dairy farms by determining and analyzing operational parameters. Seven CALs located in the main dairy basin of Mexico were analyzed. The sampling areas for each CAL were the supernatant, the active zone, settled sludge, and digester inlet and outlet. The variation of the process parameter values corroborated that CALs appeared stratified and not working as expected. The sludge zone, comprising 50-58% of total solids content and 1-15% of total CALs volume, showed an elemental compounds content suitable for organic fertilizer (340, 48, and 5 kg t-1 of C, N, and S, respectively). However, this zone contained, at least, 85% of the slowly hydrolysable material; the methanogenic potential was less than 87 mL CH4 g VS-1, and the C/N ratio ranged from 4.9 to 17, outside of the optimal range. The biogas produced did not exceed 60% of methane content and more than 3000 ppm of H2S. The sludge zone significantly influences the lagoon's dynamics since it is a nutrient sink. Furthermore, the lack of agitation is the leading cause for the low energy yield and the low removal of organic matter rate. This work provides valuable information to address the operational problems within the CALs improving our understanding that shall allow proposing reactivation alternatives.

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Cow dung (CD) is a material that has been used for millennia by humanity as a stabilizer in earth building techniques in vernacular architecture. However, this stabilization has been little addressed scientifically. In this study, the effect of CD additions was assessed on earth mortars produced with one type of earth from Brazil and two other types from Portugal (from Monsaraz and Caparica). The effect of two volumetric proportions of CD additions were assessed: 10% and 20% of earth + sand. The German standard DIN 18947 was used to perform the physical and mechanical tests, and classify the mortars. In comparison to the reference mortars without CD, the additions reduced linear shrinkage and cracking. An increase in flexural and compressive strengths was not observed only in mortars produced with earth from Monsaraz. In mortars produced with the earth from Caparica, the addition of 10% of CD increased flexural strength by 15% and compressive strength by 34%. For mortars produced with the earth from Brazil, the addition of 10% of CD increased these mechanical strengths by 40%. The increase in adhesive strength and water resistance promoted by the CD additions was observed in mortars produced with all three types of earth. Applied on ceramic brick, the proportion of 10% of CD increased the adherence by 100% for the three types of earth. Applied on adobe, the same proportion of CD also increased it more than 50%. For the water immersion test, the CD additions made possible for the mortar specimens not to disintegrate after a 30 min immersion, with the 20% proportion being more efficient. The effects of the CD on mechanical performance, including adhesion, were more significant on the tropical earth mortars but the effects on water resistance were more significant on the Mediterranean earthen mortars. CD has shown its positive effects and potential for both tropical and Mediterranean earthen plasters and renders tested, justifying being further studied as an eco-efficient bio-stabilizer.

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Escherichia coli is one of the key bacteria responsible for a variety of diseases in humans and livestock-associated infections around the globe. It is the leading cause of mortality in neonatal and weaned piglets in pig husbandry, causing diarrhea and significant harm to the industry. Furthermore, the frequent and intensive use of antimicrobials for the prevention of diseases, particularly gastrointestinal diseases, may promote the selection of multidrug-resistant (MDR) strains. These resistant genotypes can be transmitted through the excrement of animals, including swine. It is common practice to use porcine manure processed by biodigesters as fertilizer. This study aimed to examine the antimicrobial susceptibility, the presence of virulence genes frequently associated with pathotypes of intestinal pathogenic E. coli (InPEC), and antimicrobial resistance genes (ARGs) of 28 E. coli isolates collected from swine manure fertilizers. In addition, the enterobacterial repetitive intergenic consensus-PCR (ERIC-PCR) technique was used to investigate the genetic relationship among the strains. Using disk diffusion, the antimicrobial susceptibility profiles of the strains were determined. Using polymerase chain reaction (PCR), 14 distinct virulence genes associated with the most prevalent diarrhea and intestinal pathogenic E. coli (DEC/InPEC) and five ARGs were analyzed. All isolates tested positive for multidrug resistance. There was no detection of any of the 14 virulence genes associated with InPECs, indicating the presence of an avirulent commensal microbiota. Molecular classification by ERIC-PCR revealed that the majority of isolates (27 isolates) coalesced into a larger cluster with a genetic similarity of 47.7%; only one strain did not cluster in this cluster, indicating a high level of genetic diversity among the analyzed isolates. Thus, it is of the utmost importance to conduct epidemiological surveillance of animal breeding facilities in order to determine their microbiota and formulate plans to reduce the use of antimicrobials and improve animal welfare.

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The knowledge of nutrient flow in dairy farms has to be explored to find optimized strategies for efficient nutrient conversion to milk. This study aims to improve the understanding of variances in nitrogen and phosphorus balance and efficiency indicators between dairy farm systems. The study analyzed 67 dairy cattle farms located in the watershed Lajeado Tacongava, Rio Grande do Sul State, Brazil. Selected dairy farms represented three production systems: confined (3 farms); semi-confined (7 farms); pasture-based (57 farms). Input-output nutrient balances were calculated at the dairy system level for nitrogen and phosphorus over a year. Inputs are feed and fertilizer and outputs are milk and meat. The main nitrogen and phosphorus input on the all farms resulted from the feed. The average N and P surplus on pasture-based farms were 352 and 49 kg ha-1 year-1, respectively. In semi-confined systems were 508 and 63 kg ha-1 year-1 and in confined systems were 786 and 70 kg ha-1 year-1. When considering the monetary value of the total N surplus, the averages were US$ 2.615, 4.950, and 12.171 for pasture-based, semi-confined and confined systems respectively. Monetary values of P surplus were US$ 346, 588, and 1119 for pasture-based, semi-confined and confined. The productive aspects that most determined the values of N and P surplus were the total number of lactating cows and the farm area. Results indicate that surplus can partially replace chemical nitrogen fertilizer, except in the confined system, and fully replace phosphorus fertilizer. Confined farms presented values to use surplus as fertilizer greater than the crop demand. For the other production systems, it happens only for phosphorus. Large variability between dairy farms of the same production system and between different production systems was observed. It reflects the inherent productive, economic, and environmental conditions of each farm and system.

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This study explores the relationship between poultry farming's antibiotic administration practices and residual antibiotic levels in the litter before its application onto agricultural soils. Twenty-three antibiotics were performed across 19 Argentinean farms representing diverse antibiotic management practices. Analysis revealed up to 20 antibiotics from eight chemical classes in poultry litter samples, with tylosin, enrofloxacin, and salinomycin being the most relevant drugs. Farms with restricted antibiotic use in feed exhibited lower residual concentrations. A self-heating treatment was tested to reduce litter antibiotic levels. Although a 60 % reduction of antibiotics was found after treatment, prevalent compounds persisted at residual levels. Regulatory measures and comprehensive litter treatments pre-application are crucial to mitigate environmental risks. This is the first study that provides insight on the occurrence of >20 drugs in real poultry production scenarios from Latin America and demonstrates how relatively simple treatments can be readily applied to decrease the associated environmental risks.

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Brazil stands as a prominent beef producer and exporter, witnessing major transformations and expansions in its production chain over the past 20 years. These changes have prompted concerns regarding waste generation and environmental pressure. This study employs material flow analysis (MFA) to quantify nitrogen flows throughout the cattle slaughter process and subsequent beef consumption in Brazil, spanning from 2011 to 2021. The analysis encompasses co-production streams like leather, tallow, viscera, and blood. Nitrogen use efficiency (NUE) and the nitrogen cascade indicator (NCI) were used to evaluate efficiency and nitrogen accumulation in the production chain. Nitrogen inputs in the system increased by 8.47 %, while beef production rose by 7.29 %. In contrast, per capita beef consumption decreased by 1.29 kg, despite an overall consumption increase of 2.84 %, attributed to population growth in Brazil. Beef exports witnessed a notable surge of 86.03 %. Conversely, human excreta and food waste losses experienced increments of 10.88 % and 2.84 %, respectively. Examining NUE reveals the highest values during the slaughter phase (90 %), followed by processing, transportation, and storage stages (79-88 %). The consumption phase exhibited the lowest NUE values (29-34 %). Regarding the cumulative nitrogen effect, the NCI varied between 77 % and 82 % throughout the study period. This highlights opportunities for enhancing nitrogen use efficiency, particularly by addressing food waste at the consumer level. Notably, the study observes nitrogen accumulation across the Brazilian beef production chain, potentially contributing to the nitrogen cascade effect and heightening environmental pressure. Recognizing these dynamics provides avenues for targeted improvements, emphasizing the need to address nitrogen-related challenges and enhance sustainability in the beef production and consumption landscape.

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Livestock farming has exerted intense environmental pressure on our planet. The high emissions to the environment and the high demands of resources for the production process have encouraged the search for decarbonization and circularity in the livestock sector. In this context, the objective of this study was to evaluate and compare the environmental performance of two different uses for biogas generated in the anaerobic digestion of animal waste, either for electricity generation or biomethane. For this purpose, a life cycle assessment approach was applied to evaluate the potential of anaerobic digestion as a management technology for three different livestock wastes, related to beef cattle, dairy, and sheep in the Brazilian animal production context. The results suggest that the treatment scenarios focusing on biomethane generation were able to mitigate the highest percentage of damages (77 to 108%) in the global warming category when compared to the scenarios without the use of anaerobic digestion (3.00·102 to 3.71·103 kgCO2 eq) or in the perspective of electricity generation (mitigation of 74 to 96%). In terms of freshwater eutrophication, the generation of electricity (- 2.17·10-2 to 2.31·10-3 kg P eq) is more favorable than the purification of biogas to biomethane (- 1.73·10-2 to 2.44·10-3 kg P eq), due to the loss of methane in the upgrading process. In terms of terrestrial ecotoxicity, all scenarios are very similar, with negative values (- 1.19·101 to - 7.17·102 kg 1,4-DCB) due to the benefit of nutrient recovery, especially nitrogen, associated with the use of digestate as fertilizer, which was one of the critical points in all scenarios. Based on these results, it is evident that proper management of all stages of the treatment life cycle is the key to decarbonization and circularity in livestock waste management. The biogas use does not present different effects on the environmental performance of the scenarios studied, demonstrating that the purpose should be chosen according to the needs of each plant or management system.

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Antimicrobial resistance (AMR) poses a significant threat to humans and animals as well as the environment. Within agricultural settings, the utilization of antimicrobial agents in animal husbandry can lead to the emergence of antimicrobial resistance. In Chile, the widespread use of animal-derived organic amendments, including manure and compost, requires an examination of the potential emergence of AMR resulting from their application. The aim of this research was to identify and compare AMR genes found in fertilized soils and manure in Los Andes city, Chile. Soil samples were collected from an agricultural field, comprising unamended soils, amended soils, and manure used for crop fertilization. The selected genes (n = 28) included genes associated with resistance to beta-lactams, tetracyclines, sulfonamides, polymyxins, macrolides, quinolones, aminoglycosides, as well as mobile genetic elements and multidrug resistance genes. Twenty genes were successfully identified in the samples. Tetracycline resistance genes displayed the highest prevalence, followed by MGE and sulfonamides, while quinolone resistance genes were comparatively less abundant. Notably, blaOXA, sulA, tetO, tetW, tetM, aac (6) ib., and intI1, exhibited higher frequencies in unamended soils, indicating their potential persistence within the soil microbiome and contribution to the perpetuation of AMR over time. Given the complex nature of AMR, it is crucial to adopt an integrated surveillance framework that embraces the One Health approach, involving multiple sectors, to effectively address this challenge. This study represents the first investigation of antimicrobial resistance genes in agricultural soils in Chile, shedding light on the presence and dynamics of AMR in this context.

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Anaerobic digestion (AD) of swine waste allows obtaining renewable energy, biofertilizer and the reduction of environmental impacts. However, the low C:N ratio of pig manure generates high concentrations of ammonia nitrogen in the digestion process, reducing methane production. Zeolite is an effective ammonia adsorbent; thus, in this research the ammonia adsorption capacity of natural Ecuadorian zeolite was studied under different operating conditions. Subsequently, its effect on methane production from swine waste was evaluated using three doses of zeolite, 1.0, 4.0 and 8.0 g, in 1 L batch bioreactors. The results showed that the Ecuadorian natural zeolite has an adsorption capacity of around 19 mgNH3-N gZ-1 when using ammonium chloride solution and, an adsorption capacity between 37 and 65 mgNH3-N gZ-1 using swine waste. On the other hand, the addition of zeolite had a significant effect on methane production (p < 0.01). The zeolite doses that provided the highest methane production were 4.0 and 8.0 g L-1, which led to values of 0.375 and 0.365 Nm3CH4 kgVS-1, compared to the values of 0.350 and 0.343 Nm3CH4 kgVS-1 that were obtained for the treatments without addition of zeolite and using a dose of 1.0 g L-1, respectively. Addition of natural Ecuadorian zeolite meant not only a significant increase on methane production in the AD of swine waste, but also a better quality of the biogas with higher percentages of methane and lower concentrations of H2S.

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