Melatonin improves post‐thaw sperm quality after mild testicular heat stress in rams
Bibliographic record
Abstract
The objective was to determine effects of slow-release melatonin on post-thaw sperm quality in rams exposed to mild testicular heat stress (HS; scrotal neck insulation). Twelve yearling Dorset rams were randomly and equally allocated to receive either 36 mg melatonin in 1 ml corn oil or 1 ml corn oil injected subcutaneously (SQ); 15 day later, all rams had HS for 96 h (start of HS = start of Week 0). Semen was collected before HS and once weekly from Weeks 1 to 7, extended in Steridyl CSS One Step, held at 5°C for ~3 h, loaded into 0.5 ml straws, held 5 cm above liquid nitrogen for 10 min and then plunged. Computer assisted semen analysis (CASA) was conducted on frozen-thawed sperm. There were group and week effects for total and progressive motility (p < .001), plus group and week effects and group*week interactions (p < .001) for post-thaw total abnormalities, acrosome integrity, post-thaw sperm DNA fragmentation index (DFI) and high mitochondrial membrane potential (HMMP). Post-thaw sperm total and progressive motility, acrosome integrity and HMMP were higher (p < .05) in melatonin versus control groups from Weeks 1 to 7, and the melatonin group reached baseline level (pre-heat stress) at Week 7 (75.79 ± 0.96, 65.48 ± 1.51, 75.00 ± 0.89 and 67.00 ± 1.06, respectively; mean ± SEM). Conversely, post-thaw sperm total abnormalities and DFI were lower (p < .05) in melatonin versus control, and both reached baseline at Week 7 in the melatonin group (26.00 ± 0.57 and 5.66 ± 0.17, respectively). Coiled tails, distal midpiece reflexes, distal cytoplasmic droplets, ruffled acrosomes, bowed midpieces, pyriform heads and knobbed acrosomes were the most common abnormalities in both groups, with lower percentages in melatonin-treated rams. Results supported our hypothesis that HS reduces post-thaw sperm quality, and that melatonin lessens those reductions, manifested by significantly better total and progressive motility, acrosome integrity and HMMP, and fewer sperm total abnormalities and DFI.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.001 |
| 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 teacher head, 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".