INVESTIGATION OF THE SUBCLINICAL TOXICOLOGICAL EFFECTS OF ERGOT ALKALOID MYCOTOXIN (Claviceps purpurea) EXPOSURE IN BEEF COWS AND BULLS
Notice bibliographique
Résumé
In my dissertation, I examine the effects of ergot alkaloid mycotoxins on vascular and reproductive systems in beef cows and bulls. Ergot alkaloids are toxic secondary metabolites produced by the pathogenic plant fungus Claviceps purpurea. Ergot alkaloids are commonly occurring adulterating toxins in livestock feed and constitute a great concern for the health of animals that consume such feeds. Consumption of these toxins can cause a broad suite of pathophysiological effects. Relevant and up-to-date scientific information on ergotism in livestock is largely unavailable to address this growing issue. The purpose of this research was to better characterize and understand the effects of ergot alkaloids in Canadian beef cattle and to ascertain concentrations at which these effects may occur.\nIn my first two chapters, beef cows were fed increasing concentrations of ergot alkaloids over a short-term (Chapter 2) and long-term (Chapter 3) basis. As ergot alkaloids have a well-known vasoactive effect, hemodynamics of different arteries were evaluated with ultrasonography (B-mode and Doppler). In both studies, concentration-dependent, subclinical physiological changes in hemodynamics were observed in the caudal artery. These results are significant as a common end-stage manifestation of ergot alkaloid mycotoxicosis is the ischemic necrosis of the tail of exposed cattle. Further, these results indicate that subclinical changes occur at concentrations below current Canadian permissible values. Therefore, vascular changes appear to be the more sensitive indicator of ergot exposure than plasma prolactin changes in cows. Plasma or serum prolactin concentration is an accepted biomarker of ergot alkaloid exposure in livestock. \n To address the lack of pharmacokinetic information available on ergot alkaloids in cattle, I conducted two oral pharmacokinetics studies and attempted to develop an analytical method to detect ergot alkaloids in bovine plasma (Chapter 4). Although the method was promising for spiked plasma, ergot alkaloids were not detected in plasma samples collected from ergot-exposed cows. Likely, low oral bioavailability explained the lack of detection of ergot alkaloids in plasma from ergot-exposed cattle. An important practical conclusion of this work is that blood samples from suspected poisoning cases will not be clinically useful. \n In my last research chapter (Chapter 5), adult beef bulls were fed diets containing ergot alkaloids for one spermatogenic cycle (i.e., 61 days) to assess the potential negative effects of ergot exposure on sperm production or function. Results of this study indicated that ergot exposure had, at most, a subtle effect on bull sperm endpoints. However, plasma prolactin was affected by treatment. Spermatogenesis is not a sensitive endpoint for ergot exposure in adult bulls. Overall, this work answered questions related to ergot alkaloid exposure that are practically important. This work will enable policy makers to make scientifically-based decisions on guidelines for ergot alkaloids in cattle feed; will bolster the working knowledge of clinicians diagnosing and treating ergot-exposed cattle in the field; and will provide the much sought after information for producers working with ergot-contaminated grain or ergot exposed animals.
Récupéré en direct depuis OpenAlex et désinversé. Les résumés ne sont pas conservés dans cette base de données : les index inversés représentent 8,6 Go des 9,3 Go de texte de la base, et le serveur dispose de 13 Go libres.
Comment cette classification a été obtenuedéplier
Prédiction distillée sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Apprise à partir de 10 348 étiquettes directes de Codex et de 10 348 étiquettes directes de Gemma. Le mode candidate est l'union des têtes enseignantes seuillées; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont ni des étiquettes humaines ni des étiquettes directes de modèles de pointe.
Scores Codex et Gemma par catégorie
| Catégorie | Codex | Gemma |
|---|---|---|
| Métarecherche | 0,000 | 0,000 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,000 | 0,001 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,001 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,000 | 0,000 |
Scores machine (provisoires)
Les deux têtes enseignantes du modèle étudiant, lues sur ce travail. Un score ordonne la base pour la relecture; il n'affirme jamais une catégorie, et le statut de validation accompagne chaque rangée tel quel.
Scores de référence d'un modèle non mature (critères de maturité non atteints, 7 itérations). Un score ordonne; il n'affirme jamais une catégorie.
score_only:v0-immature-baseline · tel quel depuis la passe de notation : score_only signifie que le nombre peut ordonner les travaux, et qu'aucune étiquette de catégorie n'en découleClassification
machine, non validéePrédiction automatique; un appel candidat d’une seule tête enseignante, pas un consensus.
Le détail, modèle par modèle et score par score, se trouve en fin de page sous « Comment cette classification a été obtenue ».