Physical and Functional Markers of Fertility in Holstein Bulls.
Notice bibliographique
Résumé
Dairy bull semen often has wide variations in fertility, despite meeting minimum standards for quality. The objectives of this study were to compare testicular physical characteristics and sperm characteristics of Holstein bulls to identify fertility markers. Ten mature Holstein bulls (4-5 y old) were selected and classified as either low- or high-fertility (n=5 each) based on adjusted 56-d non-return rates. Scrotal measurements (scrotal circumference, scrotal neck circumference, scrotal neck length) and testicular dimensions, scrotal infrared thermograms, and testicular ultrasonographic data were recorded. Among all of these testicular physical characteristics, only testicular width was significantly lower for low- vs high-fertility bulls. Four ejaculates were collected from each bull and cryopreserved; frozen-thawed sperm from these samples were evaluated for viability, motion characteristics, ability to fertilize oocytes in vitro, and the developmental competence of resulting embryos. Flow cytometry-based analysis of sperm stained with SYBR14/PI demonstrated that low- and high-fertility bulls differed in sperm viability. The proportion of moribund sperm was higher in sperm from low- vs high-fertility bulls, and the proportion of moribund sperm were correlated with non-return rates. Based on a higher proportion of moribund sperm, expressed as a percentage of viable sperm in low- vs high-fertility bulls, we concluded that the rate of conversion of viable sperm to a moribund state was higher in low-fertility bulls, and that viability of sperm from low-fertility bulls was inherently compromised. Several sperm kinematic parameters were significantly correlated with non-return rates. Moreover, whereas post-thaw sperm from low-fertility bulls had a forward progressive motility pattern, sperm from high-fertility bulls were in transition to hyperactivated motility (based on linearity, curve line velocity and amplitude of lateral head displacement). Accordingly, a significantly lower percentage of hyperactivated sperm were present in the post-thaw semen of low- vs high-fertility bulls. Similarly, sperm selected through a sodium-hyaluronate swim-up medium (provided capacitating conditions) demonstrated that sperm from high-fertility bulls had a higher tendency to undergo hyperactivated motility. Following in vitro fertilization, the percentage of cleaved embryos were significantly lower in low- vs high-fertility bulls. In addition, 8-cell embryos, morulae, blastocysts, and hatched blastocysts (expressed as a percentage of cleaved embryos) were significantly lower in low- vs high-fertility bulls. In conclusion, testicular physical characteristics were not predictive of fertility in bulls producing semen with acceptable standards. However, proportion of moribund sperm present in frozen-thawed sperm, rate of conversion of viable sperm to a moribund state, CASA parameters, ability of sperm to undergo hyperactivation, ability of sperm to fertilize in vitro, and developmental competence of resulting embryos, were all predictive of fertility. This study received funding support from NSERC; L'Alliance Boviteq Inc., Saint-Hyacinthe, QC; Westgen, Milner, BC; Alberta Livestock and Meat Agency; and Agriculture & Food Council, AB. (poster)
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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 | 0,001 | 0,001 |
| Méta-épidémiologie (sens strict) | 0,000 | 0,000 |
| Méta-épidémiologie (sens large) | 0,000 | 0,000 |
| Bibliométrie | 0,001 | 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 ».