Endocrine profiles during doe-litter separation and the subsequent pregnancy in rabbits

This study was carried ut to determine the effects of a transient doe-litte r separation on plasma prolactin, LH, FSH, estradiol-17 beta and progestero ne concentrations before artificial insemination and during the subsequent pregnancy. Control does (n=12) had free access to nursing, whereas separate d does (n=12) were kept away from their litters for 48 hours before artific ial insemination. Both groups were inseminated on day 11 after parturition. Teat stimulation by suckling caused a high increase in prolactin concentra tions in separated does (p<0.0001). Basal prolactin concentrations were obs erved in both groups on days 8 and 18 of pregnancy. No effect of the treatm ent was detected on LH and FSH concentrations during the sampling period. A rise of estradiol-17<beta> concentrations was observed 48 hours after doe- litter separation, compared to control does and to previous values (p<0.003 ). Both groups showed low progesterone concentrations before artificial ins emination. Pregnant rabbits in both groups showed increased progesterone co ncentrations on days 8 and 18 of pregnancy. Lower estradiol-17<beta> concen trations were observed in control does on day 18 of pregnancy compared with separated rabbits (p<0.003). The results suggest that a transient separati on of nursing does from their litters before artificial insemination may pr omote high follicular steroidogenesis activity leading to increased estradi ol-17<beta> concentrations. This hormonal change could be a result of sever al stimulatory actions probably triggered by the absence of suckling episod es and may affect the luteotrophic function during the subsequent pregnancy .