SUPEROVULATORY RESPONSES TO ECG IN LLAMAS (LAMA-GLAMA)

Llamas are copulation-induced single-ovulators, and multiple ovulation and embryo transfer (MOET) methods have not yet been developed for th is species. Superovulatory responses to eCG given during an induced (G roup A) or simulated (Group B) luteal phase were investigated using ul trasound to observe ovarian follicles and corpora lutea (CLs) and plas ma progesterone was used to assess luteal function. Embryos were recov ered nonsurgically. Group A (n=19) : donors were given 8 mu g, im GnRH analogue (Day 0) to induce ovulation of a mature follicle, 1000 IU, i m eCG (Day 7), and 250 mu g PGF(2 alpha) analogue (Day 9). Group B (n= 17): donors were given a subcutaneous progestagen implant (3 mg Norges tomet) at Days 0 to 7) and 1000 IU, im eCG (Day 5). When most (>65%;) of the follicles in both Groups A and B had matured at 5 to 11 d post eCG, the donors were given 8 mu g, im GnRH and mated once (n=26) or tw ice within a 24-h interval (n=10); embryos were recovered 6 to 9 d pos t ovulation. More follicles and corpora lutea were induced in Group B than in Group A, but a similar mean number of embryos were recovered ( 1.3 vs 1.6), and a similar proportion of donors yielded multiple embry os (35 vs 32%). The embryo recovery rate was similar for Groups A and B (39 and 37%), but it was higher (P<0.001) with 2 (72%) rather than 1 (22%) mating, and it was negatively correlated with CL number (P<0.05 ). Overall, 80% of the llamas had a precocious CL and elevated plasma progesterone concentrations when multiple follicles reached maturity. This was associated with increased subsequent superovulation and embry o recovery (P<0.01). Peak plasma progesterone was positively correlate d with the CL number (P<0.05). From these results we conclude that sup erovulation may be achieved with eCG given during either an induced or a simulated luteal phase, that embryo recovery is improved following 2 matings rather than 1, and that MOET may indeed be feasible for use in the llama.