Lack of Efect of Short-term Lupin Grain Feeding on Ovulation Rate in Non-prolific Polish Mountain Ewes during the Breeding Season: Ultrasonographic and Endoscopic Assessment of Ovarian Activity

The specific changes in antral follicle numbers and wavelike development have remained unrevealed in cyclic ewes fed highprotein, highenergy lupin grain for 6 days during the luteal phase of the estrous cycle (i.e., shortterm nutritional flushing). This study was mainly conducted to determine ovarian effects of the 6day lupin grain feeding in nonprolific Polish Mountain ewes, using transrectal ovarian ultrasonography and abdominal videoendoscopy. Estrus and ovulations were synchronized in 24 ewes with progestinreleasing intravaginal sponges for 12 days during the middle portion of the breeding season (September-October; 50.0458°N, 19.8406°E). Twentyfour ewes were assigned to three equal groups (n=8 each), including the Control group being fed the maintenance diet (i.e., hayonly), Treatment 1 receiving 500 g of lupin grain once a day, and Treatment 2 receiving 250 g of lupin grain twice a day, from days 914 of the synchronized estrous cycle (day 0=first ovulation of the interovulatory period studied). No differences were observed in the mean ovulation rate among the three groups of Polish Mountain ewes (P 0.05). Ovarian antral follicles emerging in the penultimate wave of the estrous cycle in Treatment 2 ewes had a longer growth phase (P 0.05) and attained a greater diameter (P 0.05) before ovulation, in comparison to those in the other two groups. A final wave of the interovulatory interval emerged ~1 day earlier in Treatment 2 than in Treatment 1 ewes (P 0.05). Nutritional supplementation with lupin grain increased the number of 3mm follicles in Treatment 2 ewes (P 0.05). The results of this study indicated that shortterm nutritional flushing with lupin grain from mid to late luteal phase did not consistently enhance ovulatory responses in nonprolific genotypes of ewes. Although the administration of lupins altered the timing of wave emergence, ovulatory follicle diameter, or duration of different stages of the follicular lifespan, it failed to increase the number of ovulatory follicles emerging in the penultimate and final waves of the estrous cycle in non-prolific Polish Mountain sheep.