Maximising embryo production in endangered sheep breeds: in vitro procedures that complement in vivo techniques

Abstract

This study investigated the use of previously superovulated ovaries as a source of oocytes, assessing the competence of them for in vitro embryo production. Two superovulatory treatments were performed: equine Chorionic Gonadotrophin (eCG) plus porcine Follicle-Stimulating Hormone (pFSH) in a single dose or the conventional protocol of six decreasing doses of pFSH. Thirty donor ewes of the endangered Ojalada breed were given either the simplified (group S; n 015) or the decreasing-dose (group D; n 015) treatments three times at intervals of ]50 days. Ovaries were recovered on day 7 after the oestrus following the third treatment, just after embryo flushing, and the oocytes were collected to assess in vitro maturation, fertilisation and development to the blastocyst stage. The two superovulatory treatments did not differ in the mean number of oocytes selected for maturation (7.191.2 and 8.591.5 per ewe in the D and S groups, respectively). The oocytes recovered from ewes in Group D (87.5%) had a significantly (p B0.05) higher maturation rate than did those recovered from ewes in group S (75%), but no differences were found in fertilisation rate (94% and 94.6% in the D and S groups, respectively); both groups did not differ in their blastocyst rates and the total number of cells in in vitro-produced blastocysts. In the two experimental groups, 1.7 (D) and 1.8 (S) in vitro-produced blastocysts were generated per ewe, which indicate that it is feasible to combine in vivo and in vitro techniques to maximise embryo production in endangered sheep breeds.

The effect of periconceptional undernutrition of sheep on the cognitive/emotional response and oocyte quality of offspring at 30 days of age

“…After fertilization, cleaved embryos were placed in a culture medium for 8 days. Media used for oocyte collection and IVM, IVF and embryo culture have been previously described 23 …”

Periconceptional undernutrition increases quantity and quality of oocyte population, but not cognitive or emotional response of 60‐day‐old lambs

“…After fertilization, cleaved embryos were placed in a culture medium for 8 days. Media used for oocyte collection and IVM, IVF and embryo culture have been previously described (Forcada et al., ).…”

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

“…In Rasa Aragonesa ewes superovulated with FSH, Alberio et al (2002) obtained 3.7-6.2 oocytes per ewe and 85% to fertilize, and Hammami (2008) reported 6.6-11.1 oocytes per ewe and 90% selected for fertilization. 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).…”

“…Thus, after the third embryo collection, ewes are euthanized and their ovaries collected to recover their oocytes to be maturated and fertilized in vitro. Forcada et al (2011b) obtained about 16 embryos per ewe when combining in vivo and in vitro techniques. However, it was observed that the competence of the oocytes recovered at day 7 after oestrus, immediately after embryo flushing from previously superovulated ewes, was lower in those treated with a single dose of eCG plus pFSH than in those ewes treated with the standard pFSH treatment.…”

“…After fertilisation, cleaved embryos were placed in a culture medium for 8 days. Media used for oocyte collection and IVM, IVF and embryo culture have been described by Forcada et al (2011b).…”