Publicação
Safebed : improving safety and sustainability of recycled manure solids as bedding material for dairy cows
| Resumo: | ABSTRACT - SAFEBED: IMPROVING SAFETY AND SUSTAINABILITY OF RECYCLED MANURE SOLIDS AS BEDDING MATERIAL FOR DAIRY COWS - Antimicrobial resistance (AMR) and the environmental impact of livestock production pose significant challenges to sustainable dairy farming. The use of recycled manure solids (RMS) as bedding material offers economic and environmental benefits but raises concerns regarding microbial safety, including the persistence of antimicrobial-resistant bacteria and potential pathogens. This study evaluated the effects of biochar supplementation in RMS to mitigate AMR risks, enhance microbial safety, and reduce environmental emissions. Fresh RMS samples were collected from a commercial dairy farm and divided into five treatments: non-supplemented RMS (C-), acidified RMS (C+), and RMS supplemented with 2.5%, 5%, or 10% biochar. Samples were incubated for 30 days at ambient temperature, with assessments on Days 0, 5, 15, and 30. Two assays were conducted: one in a humid period (April–May) and another in a dry period (June–July). Microbial analyses included bacterial quantification, Escherichia coli and Enterococcus spp. isolation, AMR and virulence profiling, and 16S rDNA sequencing for microbial community shifts. In parallel, the environmental study examined RMS characteristics, nutrient retention, and greenhouse gas (GHG) emissions. Results from the bacterial quantification revealed no statistically significant reduction in E. coli and Enterococcus spp. counts with biochar supplementation. However, trends suggested a potential decrease in AMR and virulence factors, with reductions observed in oxytetracycline resistance and biofilm formation. In contrast, the microbiome analysis demonstrated a significant reduction in bacterial loads, with 5% biochar leading to a 59.50% decrease under humid conditions. However, Brucella spp. and Pseudomonas spp. increased in biochar amended RMS. Environmentally, the supplementation with 10% biochar significantly reduced CO₂ (32%) and N₂O (47%) emissions, stabilized nitrogen, and minimized volatilization losses. However, methane emissions were largely unaffected. Addicionally, Biochar supplementation increased micronutrient and heavy metal concentrations (except for molybdenum), as well as potassium and magnesium levels, while decreasing sodium, phosphorus, and total organic carbon content. This study highlights biochar’s potential for improving microbial safety and environmental sustainability in dairy farming. Further research should optimize biochar concentrations, assess long-term effects, and evaluate field-scale applications to fully harness its role in sustainable manure management |
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| Autores principais: | Pires, Ana José de Oliveira Nunes |
| Assunto: | Biochar Recycled manure solids Antimicrobial resistance Microbiome modulation Environmental sustainability Greenhouse gas emissions One Health Biochar Sólidos de estrume reciclado Resistência antimicrobiana Modulação do microbioma Sustentabilidade ambiental Emissões de gases com efeito de estufa Uma-só-saúde |
| Ano: | 2025 |
| País: | Portugal |
| Tipo de documento: | tese de doutoramento |
| Tipo de acesso: | acesso aberto |
| Instituição associada: | Universidade de Lisboa |
| Idioma: | inglês |
| Origem: | Repositório da Universidade de Lisboa |
| Resumo: | ABSTRACT - SAFEBED: IMPROVING SAFETY AND SUSTAINABILITY OF RECYCLED MANURE SOLIDS AS BEDDING MATERIAL FOR DAIRY COWS - Antimicrobial resistance (AMR) and the environmental impact of livestock production pose significant challenges to sustainable dairy farming. The use of recycled manure solids (RMS) as bedding material offers economic and environmental benefits but raises concerns regarding microbial safety, including the persistence of antimicrobial-resistant bacteria and potential pathogens. This study evaluated the effects of biochar supplementation in RMS to mitigate AMR risks, enhance microbial safety, and reduce environmental emissions. Fresh RMS samples were collected from a commercial dairy farm and divided into five treatments: non-supplemented RMS (C-), acidified RMS (C+), and RMS supplemented with 2.5%, 5%, or 10% biochar. Samples were incubated for 30 days at ambient temperature, with assessments on Days 0, 5, 15, and 30. Two assays were conducted: one in a humid period (April–May) and another in a dry period (June–July). Microbial analyses included bacterial quantification, Escherichia coli and Enterococcus spp. isolation, AMR and virulence profiling, and 16S rDNA sequencing for microbial community shifts. In parallel, the environmental study examined RMS characteristics, nutrient retention, and greenhouse gas (GHG) emissions. Results from the bacterial quantification revealed no statistically significant reduction in E. coli and Enterococcus spp. counts with biochar supplementation. However, trends suggested a potential decrease in AMR and virulence factors, with reductions observed in oxytetracycline resistance and biofilm formation. In contrast, the microbiome analysis demonstrated a significant reduction in bacterial loads, with 5% biochar leading to a 59.50% decrease under humid conditions. However, Brucella spp. and Pseudomonas spp. increased in biochar amended RMS. Environmentally, the supplementation with 10% biochar significantly reduced CO₂ (32%) and N₂O (47%) emissions, stabilized nitrogen, and minimized volatilization losses. However, methane emissions were largely unaffected. Addicionally, Biochar supplementation increased micronutrient and heavy metal concentrations (except for molybdenum), as well as potassium and magnesium levels, while decreasing sodium, phosphorus, and total organic carbon content. This study highlights biochar’s potential for improving microbial safety and environmental sustainability in dairy farming. Further research should optimize biochar concentrations, assess long-term effects, and evaluate field-scale applications to fully harness its role in sustainable manure management |
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