Milk Culture Results in a Large Norwegian Survey—Effects of Season, Parity, Days in Milk, Resistance, and Clustering
Bibliographic record
Abstract
A nationwide random computerized assignment survey that included 3,538 sets of 4 quarter milk samples from 2,834 dairy cows was conducted during 2000. Every fifth cow from every 50th herd was randomly selected for sampling and culture during each quarter of the year. Milk culture results of pathogens known to be related to mastitis were recorded regardless of whether mastitis had been indicated by any inflammatory measure or not. Farmers were blinded to all test results to minimize any potential interventions that might be prompted by the results. The most prevalent isolate was Staphylococcus aureus, which was identified in 8.2% of the quarter milk samples. More than 15 colony-forming units/0.01 mL of Staph. aureus were found in 4.3% of the quarter milk samples, whereas 3.5% had only 1 to 3 colony-forming units/0.01 mL. Streptococcus dysgalactiae, coagulase-negative staphylococci (CNS), and Streptococcus uberis were isolated from 1.2, 3.3, and 0.4% of quarter milk samples, respectively. No isolates were found in 76.6% of the quarter milk samples tested. Among individual cows, 22.2% had an isolate of Staph. aureus in > or = 1 quarter. Only Strep. dysgalactiae exhibited a higher prevalence with increased parity. Prevalence of Staph. aureus decreased throughout days in milk, but prevalence of Strep. dysgalactiae increased. There was a strong seasonal effect; the highest prevalence of Strep. dysgalactiae and CNS was observed during April and May (late indoor season), and the highest prevalence of Staph. aureus and Strep. uberis was observed during June and July (the outdoor season). A substantial within-cow clustering effect was found for Strep. dysgalactiae, Staph. aureus, and CNS. Additionally, a within-herd effect was found for Strep. uberis, penicillin-resistant Staph. aureus, total Staph. aureus, and CNS. No within-county cluster effect was found. Lastly, both Staph. aureus and CNS exhibited a surprisingly high seasonal effect regarding the prevalence of resistance to penicillin G. Penicillin resistance of Staph. aureus was likely due to higher prevalence of Staph. aureus as a whole, but for CNS, there was also an additional increase caused by a higher proportional rate of penicillin resistance during the late indoor season.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.002 | 0.006 |
| Meta-epidemiology (narrow) | 0.000 | 0.001 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.001 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".