Notice bibliographique
Résumé
Nutrition is the single most important factor affecting reproductive development in most livestock species. The objective of this thesis was to investigate nutritional modulation of testis development at cellular and molecular level, and sperm function in bulls. In that regard, I investigated impacts of residual feed intake (RFI)- a measure of feed efficiency, early pre-natal diet and pre-pubertal diet on reproductive potential of bulls. In my first study, I investigated impacts of selection for RFI (based on sire and dam) on the reproductive potential of bull calves. Diets of pregnant cows were modulated during early gestation to determine the individual effects of diverse genetic background for RFI and pre-natal diet and the potential interaction between these variables on reproductive potential of bull calves born to them. Selection for RFI negatively impacted reproductive development of bull calves. However, there was no interaction between pre-natal diet and RFI on the reproductive development (age at puberty, SC, sperm production potential and sperm function) of bull calves. On investigating the testes of bulls with varying RFI, I found a possible role of IGF-I signaling in modulating the differences induced by RFI (age at puberty, SC and motility). To further elucidate IGF-I signaling, puberty and its associated testicular change in bulls, I utilized tissues from a differential pre-pubertal feeding study where the pre-pubertal bulls had exhibited elevated IGF-I levels and early puberty when fed a high nutrition diet (energy and protein) from 2-32 wk of life. On evaluating the testes of pre-pubertal bulls fed high vs low diet, I detected enhanced testicular cholesterol biosynthesis and Sertoli cell maturation in the high diet bulls at 16 and 24 wk respectively, with an indirect interaction between the cholesterol biosynthesis genes and the IGF-I receptor. These results suggested that IGF-I signaling is involved in Sertoli cell function. Using a cell culture model, I successfully tested this theory and was able to prove its role in promoting cholesterol biosynthesis. When evaluating the post-pubertal testes of bulls fed differential pre-pubertal nutrition, I detected upregulated mitochondrial function both in the testes and sperm of high diet fed bulls and proposed this as a mechanism to support their greater sperm motility, sperm production potential and enhanced cholesterol biosynthesis. Considering impacts of our dietary modulation on mitochondrial function and its potential involvement in epigenetic regulation, I evaluated the sperm epigenome and detected differential methylation mainly in genes implicated in spermatogenesis, sperm function and early embryo development. To conclude, the results of my thesis offer further confirmation to the AI industry about the benefits of allocating higher nutrition to bulls during their early post-natal life. Nutritional modulation has also been validated as an effective model to study male reproductive development.
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 machine sur la base complète
Imitation des enseignantsNi prévalence calibrée, ni vérité terrain. Validation humaine à venir. Le volet Gemma est une étiquette directe du modèle pour chaque travail de la base, lue sur la notice réduite au titre. Le volet Codex est un classifieur appris des 10 348 étiquettes directes de Codex et calibré sur les taux pondérés de l'échantillon; les champs sans appui suffisant ne portent aucun appel Codex. Le mode candidate est l'union des deux volets; le consensus est leur intersection. Ces sorties portent le statut machine_predicted_unvalidated et ne sont pas des étiquettes humaines.
Scores du classifieur distillé par catégorie (deux têtes)
| 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 | 0,000 |
| Études des sciences et des technologies | 0,000 | 0,000 |
| Communication savante | 0,000 | 0,000 |
| Science ouverte | 0,000 | 0,000 |
| Intégrité de la recherche | 0,000 | 0,000 |
| Charge utile insuffisante (le modèle a refusé de juger) | 0,001 | 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 source (Gemma direct ou Codex distillé), 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 ».