Pathogenesis and mitigation of the deleterious effects of heat stress on bull reproduction
Bibliographic record
Abstract
Bull testes must be 2 to 6 0 C below body temperature for morphologically normal, motile and fertile sperm.Scrotal/testicular thermoregulation is complex, including a coiled testicular artery, surrounded by the venous pampiniform plexus comprising the testicular vascular cone, a counter-current heat exchanger.In addition, heat radiation from the scrotum, sweating, complementary arterial blood supplies, and temperature gradients in the scrotum and testes all contribute to testicular cooling.Despite a long-standing paradigm that mammalian testes are close to hypoxia and blood flow does not increase in response to testicular heating, in recent studies in mice, rams and bulls, warming the testes stimulated increased blood flow, with no indications of testicular hypoxia.Furthermore, hypoxia did not replicate the changes and hyperoxia did not provide protection.Therefore, we concluded that testicular hyperthermia and not secondary hypoxia affects spermatogenesis and sperm quality.Increasing testicular temperature causes many cellular and subcellular changes.As testicular temperature increases, the proportion of defective sperm increases; recovery is dependent upon the nature and duration of the thermal insult.Environmental control of temperature (shade, sprinklers, air conditioning) and some chemical approaches (e.g., melatonin and L-arginine) have promise in reducing the effects of heat stress on bull reproduction.
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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".