The potential to use a GnRH agonist bioimplant and injection of exogenous LH to control the time of ovulation in a multiple ovulation and embryo transfer (MOET) protocol was examined in buffalo. Mixed-parity buffalo (Bubalus bubalis; 4–15-year-old; 529±13kg LW) were randomly assigned to one of five groups (n=6): Group 1, conventional MOET protocol; Group 2, conventional MOET with 12h delay in injection of PGF2α; Group 3, implanted with GnRH agonist to block the pre-ovulatory surge release of LH; Group 4, implanted with GnRH agonist and injected with exogenous LH (Lutropin®, 25mg) 24h after 4 days of superstimulation with FSH; Group 5, implanted with GnRH agonist and injected with LH 36h after superstimulation with FSH. Ovarian follicular growth in all buffaloes was stimulated by treatment with FSH (Folltropin-V®, 200mg) administered over 4 days, and was monitored by ovarian ultrasonography. At the time of estrus, the number of follicles ≥8mm was greater (P<0.05) for buffaloes in Group 2 (12.8) than for buffaloes in Groups 1 (8.5), 3 (7.3), 4 (6.1) and 5 (6.8), which did not differ. All buffaloes were mated by AI after spontaneous (Groups 1–3) or induced (Groups 4 and 5) ovulation. The respective number of buffalo that ovulated, number of corpora lutea, ovulation rate (%), and embryos+oocytes recovered were: Group 1 (2, 1.8±1.6, 18.0±13.6, 0.2±0.2); Group 2 (4, 6.1±2.9, 40.5±17.5, 3.7±2.1); Group 3 (0, 0, 0, 0); Group 4 (6, 4.3±1.2, 69.3±14.2, 2.0±0.9); and Group 5 (1, 2.5±2.5, 15.5±15.5, 2.1±2.1). All buffaloes in Group 4 ovulated after injection of LH and had a relatively high ovulation rate (69%) and embryo recovery (46%). It has been shown that the GnRH agonist-LH protocol can be used to improve the efficiency of MOET in buffalo.
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