title: Relationships among estrous behavior, superovulatory response and grade 1 embryo sex ratio in superovulated Holstein heifers.
abstract: In this study, we first attempted to determine whether the timing of artificial insemination affects the sex ratio of seven-day-old embryos in superovulated Holstein heifers. The superovulatory treatment consisted of eight decreasing doses of FSH for 4 days and 2 doses of PGF(2alpha) given with the last two doses of FSH. The superovulated heifers were given a GnRH analogue 48 h after the first PGF(2alpha) treatment and were artificially inseminated 48 h (n=10) or 56 h (n=8) after the first PGF(2alpha) treatment. There were no significant differences in the percentages of unfertilized ova and transferable embryos (grades 1 to 3) between the two groups. The proportions of female grade 1 embryos did not significantly differ from the expected ratio of 50:50 (49.3% at 48 h and 52.5% at 56 h). We then compared the estrous behavior and superovulatory responses of the heifers with a proportion of female embryos of 50% or less (n=7, Low group) to those of the heifers with a proportion of female embryos of more than 50% (n=9, High group). The Low group had a longer duration of estrus and a higher superovulatory response than the High group. These findings offer little encouragement for prediction of the population of female embryos collected from superovulated heifers. Further studies are necessary to evaluate to what degree maternal hormone levels are related to estrus duration and sex ratio.
authors.affiliation: Zen-noh Embryo Transfer Center, Kamishihoro, Hokkaido, Japan. ideta-atsushi@zennoh.or.jp
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ideta
authors.forename: Koh
authors.initials: K
authors.lastname: Hayama
authors.forename: Manami
authors.initials: M
authors.lastname: Urakawa
authors.forename: Yeon Gil
authors.initials: YG
authors.lastname: Jung
authors.forename: Kwang Taek
authors.initials: KT
authors.lastname: Lim
authors.forename: Won You
authors.initials: WY
authors.lastname: Lee
authors.forename: Hae Bum
authors.initials: HB
authors.lastname: Song
authors.forename: Yoshito
authors.initials: Y
authors.lastname: Aoyagi
mesh_terms: D000818:Animals; D002417:Cattle; D004622:Embryo, Mammalian; D004971:Estrus / Q000502:physiology*; D005260:Female; D007315:Insemination, Artificial; D012744:Sex Ratio; D012726:Sexual Behavior, Animal; D013480:Superovulation