109 In vitro embryo production in Bos indicus donors super-stimulated with equine chorionic gonadotrophin or FSH prior to ovum pickup

An experiment was designed to evaluate a single equine chorionic gonadotrophin (eCG) or FSH administration before ovum pickup (OPU) on in vitro embryo production in Bos indicus donors. Purebred, mature, nonlactating, cycling, Gyr donor cows (n = 54), with a body condition score between 3 and 4 (scale 1–5) were randomly allocated in one of three treatment groups and treated three times, with a 21-day interval, in a crossover design (all donors received three treatments which were represented equally in each replicate). Donors in the EB + P4 + FSH and EB + P4 + eCG group received a single injection with 150 mg of progesterone (P4; Sincrogest, Ourofino, Brasil), plus 2 mg of oestradiol benzoate (EB, Gonadiol, Zoetis) intramuscularly (IM) on Day 0 and a single IM injection of 105 IU FSH (3 mL, Folltropin, Vetoquinol, USA) or 600 IU eCG (3 mL, Novormon 5000, Zoetis) on Day 4. On Day 6 in the afternoon (i.e. 36 h after FSH or eCG) cows were submitted to an OPU, performed by a single operator. Cows in the control group did not receive any hormonal treatment and were OPU at the same time as those in the FSH and eCG groups. Recovered cumulus–oocyte complexes (COCs) were classified, matured, and fertilized and presumptive zygotes were cultured in vitro for 7 days using a commercial in vitro embryo production system (Vitrogen, YVF Biotech, Brazil). Frozen/thawed semen from a single Gyr bull was used. Data were analysed using the generalized linear and mixed model procedure using treatment and replicate as fixed variables and cow as a random variable. Although the mean (±s.e.m.) of total number of COCs and viable COCs did not differ among treatment groups (P = 0.39), the number of viable (IETS grade 1 plus grade 2) blastocysts and grade 1 blastocysts (P < 0.05) were greater in cows given either FSH or eCG compared to that in untreated control cows (Table 1). No differences were detected between donors treated with either FSH or eCG. In summary, the synchronization of follicle wave emergence plus the administration of a single IM injection of FSH or eCG prior OPU increases the production of in vitro viable embryos in dairy Bos indicus (Gyr) donors.