198 Superovulatory response in cows undergoing aromatase inhibitor treatment
Notice bibliographique
Résumé
The aromatase inhibitor letrozole has been used in the treatment of infertility in women by inducing mild ovarian superstimulation or augmenting the ovarian response to FSH treatment. The effect has been attributed to an apparent up-regulation of FSH receptors on granulosa cells as a result of increased androgens (Weil et al. 1999 J. Clin. Endocrinol. Metab. 84, 2951-2956). The objective of this study was to determine whether letrozole will augment the superstimulatory response in FSH-treated cattle. Mature, non-lactating Holstein cows (n = 30) were given 2 luteolytic doses of PGF2a 12 h apart and scanned daily by transrectal ultrasonography to detect ovulation. Transvaginal ultrasound-guided ablation of follicles =5 mm was performed in all cows as a group, at 5 to 8 days after ovulation. On the day of ablation, cows were assigned randomly to 2 groups (n = 15 per group) and given either an intravaginal letrozole-releasing device or a blank device for 5 days. Coinciding with expected wave emergence (Day 0), cows in both groups were given 8 doses of 50 mg of pFSH (Folltropin; Vetoquinol, Lure, France) IM at 12-h intervals, and PGF2a on Days 3 and 3.5. At the time of the second PGF2a, vaginal devices were removed and paint was applied to the tailhead to facilitate detection of oestrus. On Day 5, cows were given gonadotropin-releasing hormone (100 mg gonadorelin) IM and artificially inseminated 12 and 24 h later. Ova/embryos were collected by transcervical uterine flush on Day 12. The ovaries were examined by ultrasonography on Day 0, 3.5, 5, 6.5, and 12 to record the follicular and luteal response. Nominal data were compared between groups by t-test and by ANOVA for repeated-measures and are expressed as mean ± s.e.m. Binomial data were compared by chi-squared test. The number of follicles at wave emergence did not differ between letrozole and control groups (24.6 ± 3.1 and 26.5 ± 3.3 respectively; P = 0.68). There was no treatment effect or treatment × day interaction in the number of follicles >8 mm on Day 3.5, 5, and 6.5. Letrozole-treated cows exhibited oestrus later than controls (50.3 ± 1.1 h v. 40.7 ± 2.0 h after first PGF2a; P < 0.001) and had less variance in interval to oestrus (residuals, 3.1 ± 0.48 h v. 6.7 ± 0.87 h; P < 0.01). The number of CL on Day 6.5 was lower in the letrozole group than in the control group (9.1 ± 1.1 v. 12.3 ± 1.1; P = 0.05). The proportion of ovulations (number of CL on Day 12 over number of follicles =3 mm on Day 0) was lower in the letrozole group than in the control group (0.65 ± 0.05 v. 0.82 ± 0.08; P = 0.02). The total number of ova/embryos collected per cow did not differ between letrozole and control groups (5.0 ± 1.9 v. 5.4 ± 1.8; P = 0.75), nor did the number of transferable embryos differ (3.0 ± 1.2 v. 4.3 ± 1.5; P = 0.56). In conclusion, treatment with a letrozole-releasing device during ovarian superstimulation did not improve the superovulatory response or embryo collection rate in mature Holstein cows, but letrozole treatment resulted in more synchronous oestrus, which may be used in the design of a fixed-time AI protocol following superstimulatory treatment in cattle. This research was supported by the Alberta Livestock and Meat Agency.
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 | 0,001 | 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) | 0,000 | 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 ».