The effect of different FSH administration before ovum pick up on superstimulation response and oocyte yield

This study aims to evaluate the effect of synchronization and different superstimulation protocols on oocyte yield before ovum‐pick up (OPU) to provide a homogeneous follicle population. Animals in all study groups except the control group applied a synchronization protocol including modified ovsynch+progesterone and dominant follicle ablation (DFA, on the 6th day following synchronization). In group 1, oocytes were retrieved by ultrasonography only on the 4th day after DFA. In group 2, 250 μg pFSH (100 μg IM, 150 μg SC) was administered as a single dose on the 2nd day following DFA, and oocytes were retrieved on the 2nd day following this injection. In group 3, 250 μg pFSH was administered IM in four equal doses 12 h apart on the 1st and 2nd days following DFA, and oocytes were retrieved 2 days after the last FSH injection. In group 4, 250 μg pFSH (IM) dissolved in Montanide ISA 206 adjuvant was administered as a single dose on the 2nd day following DFA, and oocytes were retrieved 2 days after this treatment. In the control group (group 5), oocytes were retrieved from animals without any hormonal treatment on a random day of the oestrus cycle. In order to assess the follicle population in the ovary on the day of OPU, the number of follicles according to their diameter was determined by ultrasonography in all groups. The ratio of medium‐sized follicles (3–8 mm) was higher in the synchronized groups (Groups 1, 2, 3 and 4) than in the control group (Group 5) (p