Antimicrobial Use, Resistance, and Farm Management Practices in Calves on Canadian Dairy Farms
Bibliographic record
Abstract
This thesis describes antimicrobial use and antimicrobial resistance in dairy calves, as well as an exploration of studies evaluating colostrum management practices. A scoping review was conducted to investigate the current literature on colostrum management practices and failed transfer of passive immunity in dairy calves. A total of 256 studies were included in data synthesis with 195 being controlled trials. Thirty controlled studies investigated the effect of colostral quantity at first feeding to calves, where studies were comparable with each other. Only 4 controlled trials were found on bacterial load in colostrum in relationship of transfer of passive immunity. A knowledge gap remains considering optimal colostrum management practices and calf health. \nAn observational study investigated the temporal trend of antimicrobial susceptibility in E. coli and Salmonella isolates obtained from calves ≤ 2 months old in Ontario. Among the total of 1,291 isolates, small differences were noted over 2007 - 2020; however, calves aged ≥ 2 weeks old had higher odds of resistance than younger calves. A cross-sectional study investigated treatment decisions by Canadian dairy producers when using antimicrobials for pre-weaned dairy calves. Questionnaires were distributed to 142 dairy producers, where 96% and 74% of them used antimicrobials to treat a respiratory case and a diarrhea case, respectively. Several combinations of clinical signs were used when making the treatment decision for each respiratory and diarrheic case. Producers who had a written treatment protocol for a respiratory disease had 3 times the odds of using antimicrobials by considering at least 3 respiratory signs compared to those without a protocol for calf respiratory disease. Producers who had a written treatment protocol for calf diarrhea had 7 times the odds of using antimicrobials by considering one of the systemic signs for diarrhea compared to those without a protocol for calf diarrhea. \nA cross-sectional study investigated antimicrobial use and its association with calf management practices in heifers ≤ 60 d of age on Canadian dairy farms. Among the 74 dairy farms included, 7,307 antimicrobial treatment records were collected. Florfenicol was most commonly used, with lower numbers in fluoroquinolone and ceftiofur. Farms that fed transition milk to calves had less than half the number of antimicrobial treatments/calf-year than those who did not feed transition milk.
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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 | 0.003 | 0.009 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.003 | 0.007 |
| Science and technology studies | 0.001 | 0.001 |
| Scholarly communication | 0.002 | 0.001 |
| Open science | 0.001 | 0.001 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 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".