INFLUENCE OF AGE, STIMULATION BY PMSG OR FLUSHING ON THE OVARIAN RESPONSE TO LHRHa IN YOUNG RABBIT FEMALES

[EN] Fifty young Californian rabbit females have been used to study the effect of age (14 or 17 weeks) and ovarian stimulation (nutritional flushing or PMSG) on the ovarian response to LHRHa injection. Stimulation by nutritional flushing showed, in the 14 and 17 week-old animals, a positive effect on live weight after 8 days, ovulation rate was satisfactory in females aged 17 weeks but not in the 14 week-old group, nevertheless 14 weeks old does showed an increase in the number of follicles larger than 0.6 mm (P<0.05). Stimulation by PMSG (100 IU) provoked a six folds increase in the number of follicles larger than 0.6 mm (90.6 vs 15.1; P<0.001), but failed to in crease the proportion of ovulating females, thus suggesting that a too high dose had been used. These results indicate that introduction of rabbit females to reproduction can be advanced to 17 week-old, provided that previous ovarian stimulation by nutritional flushing is done[FR] Cinquante jeunes tapines de race californienne ont été utilisées pour étudier l'effet de l'age (14 et 17 semaines) et de la stimulation ovarienne (par suralimentation ou PMSG) sur la réponse de l'ovaire a l'injection de LHRHa. La stimulation par suralimentation pour les animaux agés de 14 ou 17 semaines a un effet positif sur le poids vif, apres B jours ; le taux d'ovulation était satisfaisant pour les feme/les agées de 17 semaines mais pas pour ce/les agées de 14 semaines, bien que les feme/les agées de 14 semaines montraient une augmentation du nombre de follicules d'une taille supérieure a 0,6 mm (P<0.05). La stimulation par PMSG (100 U./.) multipliait par 6 le nombre de follicules de taille superieure a 0.6 mm (90.6vs 15.1; P