153 THE EFFECT OF CONTINUOUS EXOGENOUS GONADOTROPIN TREATMENT ON OVARIAN ACTIVITY IN TIGERS (PANTHERA TIGRIS SPP.)
Notice bibliographique
Résumé
Tigers are seasonally polyestrus, induced ovulators and can show breeding behavior for 7 days or more. The aim of this study was to determine the optimal time to trigger ovulation to induce a normal luteal phase. Previously, naturally cycling tigresses (n = 5) were observed for estrus and treated with gonadotropin-releasing hormone (GnRH) agonist. It appeared from ovarian laparoscopic examinations, fecal estrogen, and progesterone measurements, that Day 4 of estrus was optimal for timing the ovulation trigger. One of the tigresses had three 10 to 12 mm follicles and three ovulation sites on her ovaries and produced a live cub after intra-uterine laparoscopic artificial insemination using fresh semen. To control the cycle and further pinpoint the timing for ovulation, a study was conducted on three tigresses using purified pFSH, previously shown to be effective in tigers (Crichton et al. 2003 Biol. Reprod. 68, 105–113) delivered in an implantable osmotic pump (Alzet, Palo Alto, CA, USA) and GnRH agonist delivered on Day 4 of estrus. None of the females ovulated as determined by fecal progesterone measurements, which is consistent with previous anecdotal reports that GnRH agonists are effective in natural cycles but not in stimulated cycles in felids. To overcome this problem, a study was conducted on 6 tigresses (n = 11 cycles) using 210 mg pFSH (Folltropin-V, Bioniche, Belleville, ON, Canada) delivered at 1.25 U pFSH/h and the tigresses were treated on Day 4 of estrus (7 days after pFSH implantation) with 50 µg GnRH agonist (Cystorelin, Merial, Victoriaville, QC, Canada) in addition to 10 000 IU of hCG (Profasi, Serono, Rockland, MA, USA), the latter previously shown to be effective in felids (Donoghue et al. 1993 J. Zoo Wild. Med. 24, 185–189). Fecal samples were collected and analyzed for estradiol and progesterone and ovarian responses were examined laparoscopically. Results were compared using Student’s t-tests. Discrepancies in reported sample numbers were due to limited sample availability. Concentrations of fecal estradiol were similar (P > 0.05) between females treated with pFSH and natural cycles (172.5 ± 14.9 ng g–1, n = 8 v. 204.8 ± 4.1 ng g–1, n = 4; respectively). Females responded to hormonal stimulation with a significant increase (P < 0.05) in the number of large follicles (>9 mm) to CL stages compared to naturally cycling females (11.8 ± 1.9, n = 11 v. 4.0 ± 0.1, n = 5; respectively). There was no difference (P > 0.05) in the average duration of the luteal phase between stimulated and natural cycles (32.9 ± 0.1d, n = 7 v. 33.3 ± 1.4d, n = 3; respectively). Luteal phase progesterone concentrations were significantly higher (P < 0.05) after GnRH and hCG treatments than in naturally ovulating tigresses (6.3 ± 1.0 µg g–1, n = 10 v. 2.8 ± 0.6 µg g–1, n = 4; respectively). In summary, while follicular development was increased, exogenous hormone administration resulted in fecal estradiol concentrations and luteal phase duration similar to that of naturally cycling tigresses. Nevertheless, progesterone concentrations were significantly higher and follicular phase duration tended to be longer in the stimulated cycles.
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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 | 0,000 |
| 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 ».