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Comparison of duplicate and single quarter milk samples for the identification of intramammary infections
1Department of Veterinary Science, Pennsylvania State University, University Park 16802.
Abstract:
Results of bacteriological culture of 5426 pairs of duplicate quarter milk samples collected were analyzed for agreement. Overall, the percentage of agreeing pairs was 98.1%. The percentage agreement by infection type was greater for the contagious pathogens, Streptococcus agalactiae (96.4%) and Staphylococcus aureus (94.2%), than for other Streptococcus spp. (81.6%) and coliform organisms (55.6%). Single quarter samples may be adequate for determining status of quarter infection with Strep. agalactiae and Staph. aureus.
Insights
Bacteriological culture of duplicate milk samples showed high agreement (98.1%). Single quarter samples are reliable for detecting contagious mastitis pathogens like Streptococcus agalactiae and Staphylococcus aureus.
Area of Science:
- Veterinary Microbiology
- Dairy Science
- Animal Health
Background:
- Mastitis is a significant disease in dairy cattle, impacting milk production and quality.
- Accurate diagnosis of mastitis relies on reliable microbiological testing of milk samples.
- Evaluating the efficacy of different sampling strategies is crucial for efficient disease surveillance.
Purpose of the Study:
- To assess the agreement between duplicate quarter milk samples in bacteriological culture.
- To determine the reliability of single quarter samples for mastitis diagnosis.
- To compare diagnostic agreement for different mastitis-causing pathogens.
Main Methods:
- Bacteriological culture was performed on 5426 pairs of duplicate quarter milk samples.
- Percentage agreement was calculated for overall results and by specific pathogen type.
- Analysis focused on contagious pathogens (Streptococcus agalactiae, Staphylococcus aureus) and other bacteria (Streptococcus spp., coliforms).
Main Results:
- Overall agreement between duplicate milk samples was high at 98.1%.
- Higher agreement was observed for contagious pathogens: Streptococcus agalactiae (96.4%) and Staphylococcus aureus (94.2%).
- Lower agreement was found for Streptococcus spp. (81.6%) and coliform organisms (55.6%).
Conclusions:
- Single quarter milk samples demonstrate adequate reliability for detecting infections with Streptococcus agalactiae and Staphylococcus aureus.
- The findings support the potential use of single quarter samples in mastitis screening programs for specific contagious pathogens.
- Diagnostic accuracy varies by pathogen, highlighting the importance of considering pathogen type in sampling strategies.