Yucca schidigera extract can promote rabbit fecundity and ovarian progesterone release

The aim of the present in vivo study was to determine the effects of yucca powder extract added to the rabbit females feed mixtures on kindling and conception rate. Rabbit does of the experimental groups were fed with the standard diet enriched with supplement of yucca dry extract at doses of 5 g/100 kg feed (E1 group) or 20 g/100 kg feed (E2 group) for 50 days. In our preliminary in vivo results we shown, that conception rate was significantly higher in both experimental E1 and E2 groups (82.4% and 100.0%, respectively) than in control group (47.1%). The kindling rate was also significantly higher in the experimental groups (70.6% and 100.0%, respectively) than in the control group (41.2%). The differences between control and yucca treated groups in the number of liveborn, stillborn and weaned pups per doe were not statistically significant. To understand possible endocrine mechanisms of yucca action on fertility rate, we have examined the influence of yucca extract additions on the release of steroid hormones by isolated and cultured rabbit ovarian fragments. Yucca additions promoted release of progesterone (at dose 1 μg.ml-1, but not at doses 10 and 100 μg.ml-1). Yucca addition at these doses did not affect testosterone or estradiol release. Our observations demonstrate the stimulatory effect of yucca consumption on rabbit fecundity, which can be due to its direct stimulatory influence on ovarian progesterone, but not testosterone or estradiol output.