244 DEVELOPMENT OF SUPEROVULATORY STRATEGIES IN ALPACAS

Abstract

The objective of the present study was to determine the ovarian response of alpacas to different treatments for follicular development and superovulation. Twenty-nine mature, lactating alpacas, between 31 and 56 days postpartum, managed in the Peruvian highlands (altitude = 4100 m) were randomly distributed into 4 experimental groups. Groups 1 (n = 7) and 3 (n = 8) received a homemade intravaginal sponge containing 60 mg of medroxyprogesterone acetate (MAP; Sigma Chemical Co., St Louis, MO, USA) plus 2 mL of PGF_2α (IM; Illiren^®; Intervet International, Boxmeer, The Netherlands) on Day 0. Groups 2 (n = 7) and 4 (n = 7) received 2 mL of PGF_2α (IM) on Day 0, but did not receive a MAP sponge. All groups received 6 injections (IM) of FSH (Folltropin V^®; Bioniche Animal Health, Beltsville, Ontario, Canada) in decreasing dosages of 50, 50, 30, 30, 20, and 20 mg, respectively, every 12 h (at 0700 and 1900 h each day), plus 300 IU of eCG (IM; Folligon^®; Intervet International) at the time of the last FSH treatment, with the aim of increasing LH levels. The FSH treatments started on Days 7, 5, 9, and 7 (from Day 0) in groups 1–4, respectively. MAP sponges were removed at the time of the last FSH treatment in groups 1 and 3. All alpacas were naturally mated twice at 12 and 24 h after the last FSH treatment. Alpacas in groups 1 and 2 received 3000 IU of hCG (IM; Corulon^®; Intervet International) and alpacas of groups 3 and 4 received 2.5 mL of GnRH (IM; Conceptal^®; Intervet International) immediately after the first mating. Seven days after the first mating, ovaries of all alpacas were examined by transvaginal ultrasonography. Ovarian response was estimated by determining the number of CL present on each ovary. The numbers of follicles that were at least 8 mm in diameter were also counted. Data were analyzed as a complete randomized design with 4 treatments. The average number of CL per alpaca was 1.3, 1.00, 1.00, and 0.9 for groups 1 to 4, respectively (P > 0.05). The average number of follicles that were at least 8 mm in diameter per alpaca was 9.4, 20.4, 0.9, and 3.9 for groups 1 to 4, respectively (P ≤ 0.05) with females in group 2 showing the highest response. We conclude that progestin treatment did not affect ovulatory response of lactating alpacas to exogenous gonadotropins. An effective ovarian stimulation strategy for achieving superovulation in alpacas remains to be developed.