228 DOMINANT FOLLICLE ABLATION IMPROVES SUPEROVULATORY RESPONSE AND EMBRYO YIELD IN BUFFALOES SUBJECTED TO INTEGRATED SINGLE-OVULATION EMBRYO TRANSFER–MULTIPLE-OVULATION EMBRYO TRANSFER PROGRAM

Abstract

Effect of the removal of inhibitory consequences of a dominant follicle (DF) on the recruitment, growth and ovulation of follicles in cyclic buffaloes induced to superovulate, was evaluated. Eight elite, multiparous, donor Murrah buffaloes, 80 to 120 days postpartum, were included in an integrated single-ovulation embryo transfer–multiple-ovulation embryo transfer (SOET-MOET) schedule. Superovulation with FSH (Folltropin^® NIH-FSH-P1, Bioniche Animal Health, Belleville, ON, Canada) was preceded by nonsurgical single embryo (SOET) recovery on Day 5 or 6 after prostaglandin F_2α (Lutalyse^®, Pfizer, Madison, NJ, USA)-induced oestrus and AI (Day 0). For MOET, Folltropin was administered from Day 9 p.m. through to Day 13 p.m. in a twice-daily descending dose schedule (0–5, 5–4, 4–3, 3–2, 2–1 mL; total dose of 580 mg of NIH-FSH-P1). A dose of 25 mg of Lutalyse was administered on Day 12 a.m. and p.m. Donors were inseminated with proven semen on Day 14 a.m. and p.m. and Day 15 a.m. Nonsurgical embryo collection was carried out on Day 19 or 20 followed by administration of Lutalyse on Day 25. Following sexual rest for one complete oestrous cycle, Day 5 or 6 SOET was repeated. On Day 9, ultrasound-guided follicle aspiration was used to ablate the DF and the second MOET treatment was initiated at the same time. Mean diameter of DF at the start of superovulation treatment on Day 9 was similar between the first (12.5 ± 0.66 mm) and second (12.2 ± 0.33 mm) MOET cycles. At AI, mean number (9.6 ± 1.43 vs 13.4 ± 1.87) of follicles >9 mm were higher (P < 0.05) in the second (ablation) MOET cycle, though their mean diameters were similar (11.7 ± 0.21 vs 12.3 ± 0.21 mm; P = 0.17). On the day of ova/embryo collection, almost similar numbers of large follicles (4.1 ± 0.93 and 4.4 ± 0.84), with mean diameters of 12.9 ± 0.74 and 13.4 ± 0.83 mm, were observed for the first and second MOET, respectively. Mean (± SEM) numbers of corpora lutea (3.9 ± 0.81 and 4.9 ± 0.61; P = 0.19) and transferable quality embryos (0.6 ± 0.37 and 1.6 ± 0.37; P = 0.077) were counted in the first and second (ablation) MOET cycles, respectively. These preliminary findings suggest that ablation of DF before start of superovulatory treatment may be beneficial in improving the yield of transferable embryos in a buffalo MOET program.

Director, CIRB, is acknowledged for the experimental facilities.