Effects of chlortetracycline and Synovex-S<sup>®</sup> on growth rate and on plasma growth hormone and thyroid hormone concentrations following administration of thyrotropin-releasing hormone and GH-releasing hormone in beef steers
Bibliographic record
Abstract
Twenty-four Angus steers (365 kg ± 4) were assigned randomly to a 2 × 2 factorial arrangement of treatments of either 0 or 350 mg chlortetracycline d-1, with or without Synovex-S to test the effects of chlortetracycline (CTC) and estrogenic implant on release of growth hormone (GH) and thyroid hormones. Steers received ad libitum a concentrate-forage diet over a 112-d feeding study, and growth and carcass characteristics were determined. On days 30, 56, and 106, steers received an injection, via jugular catheter, of 1.0 µg kg-1 BW thyrotropin-releasing hormone (TRH) + 0.1 µg kg-1 BW GH-releasing hormone (GHRH) and blood was collected from -30 to 360 min post-injection. Overall, compared with non-implanted steers, Synovex-S increased (P ≤ 0.009) rate and efficiency of gain, decreased (P = 0.05) time to peak for GH concentrations, whereas baseline concentrations of thyroid-stimulating hormone (TSH) were increased (P = 0.03). Additionally, the TSH response curve (P ≤ 0.05) and magnitude of triiodothyronine (T3; P = 0.01) response were greater following TRH + GHRH challenge for implanted versus nonimplanted steers. There were no main effects of CTC; however, CTC attenuated (P ≤ 0.05) the effects of implant on T3 release, slaughter weight, and carcass composition. In conclusion, Synovex-S alone increased BW gain and enhanced the response of GH, TSH, and T3 to a TRH + GHRH challenge, whereas CTC alone did not affect rate and composition of gain or release of pituitary and thyroid hormones. However, CTC appeared to mitigate the effects of implant on T3 release and carcass composition. Key words: Growth hormone, thyroid, estrogen, chlortetracycline, bovine, growth
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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 | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 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".