Investigation into an ongoing dilemma: undefined welfare implications challenging the use of β-adrenergic agonists in beef production
Bibliographic record
Abstract
Beta-adrenergic agonists (βAA) are administered during the final weeks of the beef production system to improve efficiency and increase meat yield.Welfare concerns linked to the administration of βAA have garnered significant attention in recent years due to anecdotal reports of increased mortality during βAA feeding periods and cattle without obvious disease or injury having difficulty walking at abattoirs being overrepresented in cattle fed βAA.Thomson et al. (2015) reported 2 events where cattle were distressed, became non-responsive to handling, sloughed hoof walls and were euthanized while in lairage at the abattoir.Consistent blood abnormalities in euthanized cattle included elevated blood lactate (25.6 mmol/L; ref. range: < 4-5) and creatine kinase (CK; 6,890 U/L, ref. range: 159-332).Although no causal relationship had been established, dialogues among groups of packers, animal scientists, and welfare experts implicating the βAA zilpaterol hydrochloride (ZIL; Zilmax ® , Merck Animal Health, Desoto, KS) as one possible etiology resulted in a major beef packer announcing plans to stop accepting cattle fed ZIL.Consequently, Merck announced a self-imposed suspension of ZIL sales in U.S. and Canadian markets until further research could be conducted to investigate the manner.Utilization of technologies such as βAA are imperative to meeting the demands of a growing world population and verdicts regarding such technologies, including their impact on animal welfare, should be based on scientific merit.The first objective of this research was to evaluate the effect of shade on performance and animal well-being in cattle fed ZIL.The second objective was to characterize the clinical description and hematological profile of fatigued cattle presented to abattoirs.The third objective was to evaluate the effects of handling intensity during shipment for slaughter in cattle fed a βAA.The fourth objective was to evaluate the effects of βAA administration on performance and physiological response to different handling intensities during shipping for slaughter.Shade provision reduced open-mouth breathing and increased dry matter intake and dressing percentage.Fatigued cattle observed at abattoirs had increased respiratory rates and muscle tremors, although blood parameters were relatively normal compared to their cohorts.Metabolic acidosis, a precursor for Fatigued Cattle Syndrome, was observed in cattle exposed to aggressive handling regardless of βAA status.This research confirms the improved growth performance of cattle fed βAA and highlights the improvement of animal welfare through shade provision and low-stress handling in heavy-weight feedlot cattle.
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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 | 0.036 | 0.059 |
| Meta-epidemiology (narrow) | 0.001 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.001 |
| Bibliometrics | 0.001 | 0.001 |
| Science and technology studies | 0.007 | 0.013 |
| Scholarly communication | 0.010 | 0.009 |
| Open science | 0.004 | 0.005 |
| Research integrity | 0.012 | 0.015 |
| Insufficient payload (model declined to judge) | 0.009 | 0.002 |
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".