Relationships among Estrous Behavior, Superovulatory Response and Grade 1 Embryo Sex Ratio in Superovulated Holstein Heifers

摘要: In this study, we first attempted to determine whether the timing of artificial insemination affects sex ratio seven-day-old embryos in superovulated Holstein heifers. The superovulatory treatment consisted eight decreasing doses FSH for 4 days and 2 PGF(2alpha) given with last two FSH. heifers were a GnRH analogue 48 h after artificially inseminated (n=10) or 56 (n=8) treatment. There no significant differences percentages unfertilized ova transferable (grades 1 3) between groups. proportions female grade did not significantly differ from expected 50:50 (49.3% at 52.5% h). We then compared estrous behavior responses proportion 50% less (n=7, Low group) those more than (n=9, High group). group had longer duration estrus higher response group. These findings offer little encouragement prediction population collected Further studies are necessary evaluate what degree maternal hormone levels related ratio.