Simplified superovulatory treatments in Corriedale ewes

Does supplemental LH changes rate and time to ovulation and embryo yield in Santa Ines ewes treated for superovulation with FSH plus eCG?

“…In a previous study, the interval between sponge removal and the preovulatory LH surge was 37.2±0.7h (ranging from 24 to 48h), whereas the mean time for the onset of ovulation was 65.4±0.7h (ranging from 47 to 79h) in ewes subjected to SOV using only FSH (VEIGA-LOPEZ et al, 2008). According to SIMONETTI et al (2008), the preovulatory LH peak occurs approximately 47.4±1.9h after sponge removal when FSH is administered during four days without the use of eCG. The same authors reported the occurrence of a delayed preovulatory LH surge when eCG was not administrated.…”

“…The effects of this procedure are still unclear and may differ between different genotypes (COGNIÉ et al, 1986;PICAZO et al, 1996). The literature shows that breed differences in follicle growth, ovulation rate and fluctuations of FSH and LH lead to differential responses to exogenous gonadotrophins (AMMOUN et al, 2006;SIMONETTI et al, 2008), emphasizing the need for specific treatments for each breed. The breed factor accounted for approximately 30% of the variability in the embryo yields obtained in response to FSH treatments (VIVANCO et al, 1994).…”

Short communication. In vitro embryo production can be modified by the previous ovarian response to a superovulatory treatment in sheep

“…In this context, results obtained in the present study by those ewes which did not respond to the superovulatory treatment are especially remarkable, since 20-30% of the animals present a lack of response to FSH-based superovulatory protocols (Forcada et al, 2000(Forcada et al, , 2011b(Forcada et al, , 2012. In fact, early luteal regression is assumed as a failed response to superovulation and has also been reported by our group in both Rasa Aragonesa and Ojalada breeds (Forcada et al, 2000(Forcada et al, , 2006(Forcada et al, , 2011a, although always associated with multiple FSH injection protocols, not including eCG (Simonetti et al, 2008;Forcada et al, 2011b). This regression after superovulatory treatments seems to be related with a lack of progesterone priming before treatment, so that its incidence should be higher during anestrus (Ryan et al 1991).…”

“…However, a reduced eCG dose in combination with FSH could be enough to support follicular growth and avoid premature CL regression. Thus, previous results of our group applying the same treatment in Corriedale (Simonetti et al, 2008) or Ojalada ewes (Forcada et al 2011a) presented a low percentage of CL regression. The low maturation and fertilization rates exhibited by the oocytes recovered from ewes that only produced oocytes after superovulation and natural mating, clearly show that the ewes superovulated with fertilization problems in vivo cannot be used as oocyte donors.…”

Induction of follicular luteinization by equine chorionic gonadotropin in cyclic guinea pigs

“…As reported, the dosage of gonadotropin to induce superovulation should be based on body weight (Rahman et al, 2014). Superovulation can be induced by 5-10 IU eCG in female mice (Kanter et al, 2004;Wei et al, 2014), 500-600 IU eCG in ewes (Leoni et al, 2001;Simonetti et al, 2008;Forcada et al, 2011), and 2000-3000 IU eCG in cows (Bó and Mapletoft, 2014). During the biphasic follicular growth in guinea pigs, the first phase culminates on cycle Days 10-11 (Bland, 1980;Hutz et al, 1990), and the dominant follicle is transformed on cycle Day 12 (Shi et al, 2000).…”