190 Assessment of porcine follicle-stimulating hormone delivery mode before ovum pickup and in vitro embryo production in pregnant heifers

Administration of porcine follicle-stimulating hormone (pFSH) before ovum pickup (OPU) in cattle enhances ovarian response and in vitro embryo production (IVEP). Owing to its short half-life, multiple administrations of pFSH are commonly used. A single administration of pFSH diluted in hyaluronan, however, has been utilised as a simpler approach. The aim of this study, therefore, was to evaluate the effect of pFSH delivery mode before OPU on ovarian response and embryo yield. Pregnant Holstein heifers (n = 65) at 58 ± 13 days of gestation with moderate body condition score were assigned in a 3-treatment crossover design to one of the following groups based on the delivery mode of 200 mg of pFSH (Folltropin-V, Vetoquinol): four 50-mg administrations (12 h apart) of pFSH in 0.9% sodium chloride (multiple), single administration of pFSH in 0.5% hyaluronan (MAP-5), or single administration of pFSH diluted in 0.9% sodium chloride (saline). A 14-day washout period was applied between sessions. Follicular wave emergence was synchronized using follicle ablation and pFSH treatments initiated 36 h later. Ovum pickup was performed 40 or 50 h after the last pFSH injection for the multiple and single (MAP-5 and saline) groups, respectively. Cumulus–oocyte complexes (COCs) were subjected to standard IVEP. Ultrasonography was performed before OPU, and follicles classified as small (<6 mm), medium (6–10 mm), and large (>10 mm). Data were analysed using generalized linear mixed models and results are shown in Table 1. Although total follicles were not different (P = 0.3), multiple heifers had greater (P < 0.05) number of medium and large follicles than saline heifers, whereas MAP-5 heifers were intermediate. Recovery (COCs/follicles) was less (P < 0.01) for saline (71.4% ± 4.5) than for multiple heifers (77.7% ± 3.8), whereas MAP-5 heifers were intermediate (73.5% ± 4.3). Number of COCs was greater (P < 0.05) for multiple than for saline and MAP-5 heifers. Viable COC (%) was greater (P < 0.05) for multiple than saline heifers, whereas MAP-5 heifers were intermediate. Cleavage (%) was greater (P < 0.05) for multiple than both saline and MAP-5 heifers. Embryo (%) was greater (P < 0.05) for both multiple and MAP-5 heifers than for those in the saline group. Heifers in the multiple group yielded 2.1 and 1.2 additional (P < 0.05) embryos than those in the saline or MAP-5 group, respectively. In conclusion, use of multiple pFSH administrations enhances ovarian response and oocyte developmental competence, leading to greater embryo yield. Nevertheless, use of a single pFSH administration in hyaluronan improves oocyte competence and embryo yield compared with a single administration in saline.