Analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern Chile
Waste milk (WM), a byproduct of dairy production, is often used as a cost-effective feed for calves, but it can contain pathogens and antimicrobial residues, which pose health risks. This study examined the microbiological quality and the presence of antimicrobial residues in WM from 36 dairy farms...
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Frontiers Media S.A.
2025-08-01
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| Series: | Frontiers in Veterinary Science |
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| Online Access: | https://www.frontiersin.org/articles/10.3389/fvets.2025.1613185/full |
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| author | Fernando Ulloa Fernando Ulloa Martina Penati José M. Hernández-Agudelo José M. Hernández-Agudelo Carlos Tejeda Pamela Steuer María Filippa Addis Armin Mella Nivia Canales Juan Pablo Soto Miguel Salgado |
| author_facet | Fernando Ulloa Fernando Ulloa Martina Penati José M. Hernández-Agudelo José M. Hernández-Agudelo Carlos Tejeda Pamela Steuer María Filippa Addis Armin Mella Nivia Canales Juan Pablo Soto Miguel Salgado |
| author_sort | Fernando Ulloa |
| collection | DOAJ |
| description | Waste milk (WM), a byproduct of dairy production, is often used as a cost-effective feed for calves, but it can contain pathogens and antimicrobial residues, which pose health risks. This study examined the microbiological quality and the presence of antimicrobial residues in WM from 36 dairy farms in southern Chile. In a cross-sectional study, WM samples were collected, and farm management data were gathered through a questionnaire. The samples were analyzed for total bacterial load, coliforms, staphylococci, streptococci/streptococci-like organisms (SSLOs), Salmonella spp., Mycobacterium avium subsp. paratuberculosis (MAP), Mycobacterium bovis, Mycoplasma spp., Prototheca spp., methicillin-resistant Staphylococcus aureus (MRSA), and extended-spectrum beta-lactamase (ESBL)-producing E. coli. Antimicrobial residues were detected using a commercial test. A high average bacterial load (7.63 × 106 CFU/mL) and significant levels of staphylococci, SSLOs, and coliform were found. In addition, S. aureus (33.3%), MAP (11.1%), and Salmonella spp. (2.8%) were detected. ESBL-E. coli was found on five farms, with blaCTX-M being the predominant gene. Antimicrobial residues, mainly beta-lactams, were present in 55.6% of samples. These results show that WM in this region frequently contains pathogens, antimicrobial residues, and resistant bacteria. Current farm practices, such as feeding untreated WM to calves, may contribute to the spread of antimicrobial resistance and compromise calf health. |
| format | Article |
| id | doaj-art-6c6d15235ac64a2cba24bbce0e478fbc |
| institution | DOAJ |
| issn | 2297-1769 |
| language | English |
| publishDate | 2025-08-01 |
| publisher | Frontiers Media S.A. |
| record_format | Article |
| series | Frontiers in Veterinary Science |
| spelling | doaj-art-6c6d15235ac64a2cba24bbce0e478fbc2025-08-20T02:47:47ZengFrontiers Media S.A.Frontiers in Veterinary Science2297-17692025-08-011210.3389/fvets.2025.16131851613185Analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern ChileFernando Ulloa0Fernando Ulloa1Martina Penati2José M. Hernández-Agudelo3José M. Hernández-Agudelo4Carlos Tejeda5Pamela Steuer6María Filippa Addis7Armin Mella8Nivia Canales9Juan Pablo Soto10Miguel Salgado11Facultad de Ciencias Veterinarias, Instituto de Medicina Preventiva Veterinaria, Universidad Austral de Chile, Valdivia, ChileEscuela de Graduados, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, ChileDepartment of Veterinary Medicine and Animal Sciences, University of Milan, Lodi, ItalyFacultad de Ciencias Veterinarias, Instituto de Medicina Preventiva Veterinaria, Universidad Austral de Chile, Valdivia, ChileEscuela de Graduados, Facultad de Ciencias Veterinarias, Universidad Austral de Chile, Valdivia, ChileFacultad de Ciencias Veterinarias, Instituto de Medicina Preventiva Veterinaria, Universidad Austral de Chile, Valdivia, ChileFacultad de Ciencias Veterinarias, Instituto de Medicina Preventiva Veterinaria, Universidad Austral de Chile, Valdivia, ChileDepartment of Veterinary Medicine and Animal Sciences, University of Milan, Lodi, ItalyFacultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, ChileFacultad de Ciencias, Instituto de Bioquímica y Microbiología, Universidad Austral de Chile, Valdivia, ChileProlesur Los Lagos, Los Lagos, ChileFacultad de Ciencias Veterinarias, Instituto de Medicina Preventiva Veterinaria, Universidad Austral de Chile, Valdivia, ChileWaste milk (WM), a byproduct of dairy production, is often used as a cost-effective feed for calves, but it can contain pathogens and antimicrobial residues, which pose health risks. This study examined the microbiological quality and the presence of antimicrobial residues in WM from 36 dairy farms in southern Chile. In a cross-sectional study, WM samples were collected, and farm management data were gathered through a questionnaire. The samples were analyzed for total bacterial load, coliforms, staphylococci, streptococci/streptococci-like organisms (SSLOs), Salmonella spp., Mycobacterium avium subsp. paratuberculosis (MAP), Mycobacterium bovis, Mycoplasma spp., Prototheca spp., methicillin-resistant Staphylococcus aureus (MRSA), and extended-spectrum beta-lactamase (ESBL)-producing E. coli. Antimicrobial residues were detected using a commercial test. A high average bacterial load (7.63 × 106 CFU/mL) and significant levels of staphylococci, SSLOs, and coliform were found. In addition, S. aureus (33.3%), MAP (11.1%), and Salmonella spp. (2.8%) were detected. ESBL-E. coli was found on five farms, with blaCTX-M being the predominant gene. Antimicrobial residues, mainly beta-lactams, were present in 55.6% of samples. These results show that WM in this region frequently contains pathogens, antimicrobial residues, and resistant bacteria. Current farm practices, such as feeding untreated WM to calves, may contribute to the spread of antimicrobial resistance and compromise calf health.https://www.frontiersin.org/articles/10.3389/fvets.2025.1613185/fullantimicrobial resistancecalvescalf diseasegrazingESBL |
| spellingShingle | Fernando Ulloa Fernando Ulloa Martina Penati José M. Hernández-Agudelo José M. Hernández-Agudelo Carlos Tejeda Pamela Steuer María Filippa Addis Armin Mella Nivia Canales Juan Pablo Soto Miguel Salgado Analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern Chile Frontiers in Veterinary Science antimicrobial resistance calves calf disease grazing ESBL |
| title | Analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern Chile |
| title_full | Analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern Chile |
| title_fullStr | Analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern Chile |
| title_full_unstemmed | Analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern Chile |
| title_short | Analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern Chile |
| title_sort | analysis of pathogenic bacteria and antimicrobial residues in bovine waste milk on dairy farms in southern chile |
| topic | antimicrobial resistance calves calf disease grazing ESBL |
| url | https://www.frontiersin.org/articles/10.3389/fvets.2025.1613185/full |
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