Comparison of two different times period of FSH therapy on developmental competence of bovine oocytes collected through Transvaginal aspiration

Oocyte quality is one of the most important factors in embryo production through in vitro fertilization (IVF). Developmental competence of an oocyte is highly depended on the follicular microenvironment. In this study, the effect of ? hormonal superstimulation regimes (? doses and ? doses of FSH) on developmental competence of oocytes, obtained by ovum pick up (OPU) procedure, was evaluated in cattle species. One hundred and twenty Holstein heifers with an average age of ?? months were divided into ? groups of ?? animals. The animals in each group received either ? or ? equal doses of FSH (each dose= ?? mg) at ??h interval. The FSH treatment was started ? days after dominant follicle ablation. The ablation of dominant follicle (s) was done ? days after synchronized estrous. After OPU, ?? h after the end of FSH therapy, the aspirated oocytes were evaluated morphologically and considered for in vitro maturation, IVF, and subsequent embryo culture. In days ? and ?, cleavage and blastocyst rates were evaluated. The mean numbers of aspirated follicles, ?.??±?.? and ??.?±?.?, and retrieved oocytes, ?.?? ± ?.? and ?.?? ± ?.?, in treated animal with ? and ? doses of FSH respectively, were significantly different. The difference in percentage of grade A oocytes in ? and ? doses of FSH groups was insignificant. The rate of cleavage in animals treated with ? and ? doses of FSH was ??.?? ± ?.?? and ??.?? ± ?.??, respectively, which was not significant. Blastocyst rate in ? dose FSH group, ??.?±.?, was significantly higher than that of ? dose FSH group, ??.? ± ?.??.This study showed that in cattle, the long-term administration of FSH (three days compared to one day) prior to OPU resulted in more follicles with the higher developmentally competent oocytes, compared to the short term FSH therapy.