Biomedical subjects

Y Cognié

Publications and source records attributed to Y Cognié.

At least 19 recordsLinked to original sources

PubMed2006

Laparoscopic ovum pick-up and in vitro production of sika deer embryos: effect of season and culture conditions.

Amongst the 200 deer subspecies worldwide, more than 40 are considered as endangered. In vitro embryo production may represent an efficient way to produce and disseminate offspring from sparse remaining individuals in these species. With a view to establishing a method of in vitro embryo production, we assessed the ovarian response after hormonal stimulation (oFSH), oocyte yield following laporoscopic ovum pick-up (LOPU) and oocyte developmental competence according to seasonal reproductive status in sika deer (Cervus nippon nippon). Twelve adult sika deer hinds were allocated between two groups and submitted weekly to oFSH follicular growth stimulation followed by LOPU. Hinds in Group A (n=6) were treated first during the breeding season (5 weeks), and then during the non-breeding season (3 weeks). Hinds in Group B (n=6) were submitted to similar procedures but in the reverse order (treated first during the non-breeding season). Cumulus-oocytes complexes (COC) recovered from Group B were allowed to mature in vitro for 24 h in TCM-199 medium supplemented with oFSH, goat follicular fluid and 100 microM cysteamine. In vitro fertilization was performed with frozen/thawed semen in SOFaa medium supplemented with 20% estrous sheep serum and presumptive zygotes were cultured in the presence or absence of ovine oviductal epithelial cell monolayer (oOEC) in SOFaa-BSA medium. Mean number of follicles aspirated per hind per session decreased significantly between breeding and non-breeding season in Group A (9.8+/-0.7 versus 3.2+/-0.7, mean+/-S.E.M., respectively, P<0.001) but did not change between the non-breeding and the subsequent breeding season in Group B (5.3+/-0.7 and 5.7+/-0.7, respectively, P>0.05). Irrespective of the season, good quality COC with complete and compact cumulus investments were recovered allowing a high cleavage rate after in vitro maturation and fertilization. Whereas development to the blastocyst stage did not occur in SOF medium alone, high development rates to the blastocyst stage were observed in oOEC co-culture regardless of season (22% and 34% of total oocytes in co-culture during non-breeding and breeding season, respectively).

Animals↗

PubMed2006

Improved vitrification method allowing direct transfer of goat embryos.

The aim of this study was to design a vitrification method suited to field embryo transfer experiments in goat. In a first experiment, a standard vitrification protocol, previously designed for sheep embryos was compared to slow freezing of goat embryos. No significant difference was observed on kidding rate (48% versus 69%, respectively), nor on embryo survival rate (35% versus 45%). Second experiment: all embryos were vitrified. After warming, embryos were either transferred directly (direct transfer), or after in vitro dilution of the cryoprotectants (conventional transfer). The kidding rate was not affected by the transfer method (38% versus 23%, respectively). However, embryo survival rate tended to be higher after direct transfer (26% versus 14%). Third experiment: OPS vitrification was compared to standard vitrification. The kidding rate was not affected (22% versus 39%, respectively), but the embryo survival rate was lower after OPS (14% versus 28%). Fourth experiment: 0.4M sucrose was added with cryoprotectants in vitrification. The kidding rate after direct transfer was significantly enhanced after addition of sucrose (56% versus 27%, respectively), whereas embryo survival rate was not significantly affected (32% versus 18%). Fifth experiment: vitrification with sucrose supplementation was compared to slow freezing. No significant difference was observed after direct transfer on kidding rate (52% versus 31%, respectively), but embryo survival rate tended to be higher after vitrification (34% versus 21%). In conclusion, our results indicate that addition of 0.4M sucrose in association with direct transfer improves significantly the viability of goat vitrified embryos.

Animals↗

PubMed2005

Successful use of oviduct epithelial cell coculture for in vitro production of viable red deer (Cervus elaphus) embryos.

Techniques for in vitro production (IVP) of viable embryos have been thoroughly developed in several domestic species in view to improve breeding efficiency. When applied to wild life, these techniques may also help the maintenance of biodiversity through amplification of sparse animals offspring and facilitation of genetic material exchange. During the successive steps of IVP, i.e. oocyte in vitro maturation (IVM), fertilization (IVF) and early embryo development (IVD) to the blastocyst stage, gametes and embryos are faced with unusual environment, including oxidative stress, known to be detrimental to their survival. In the present study, starting from methods developed in domestic species, we have adapted IVP to produce viable red deer embryos. In a first experiment, cumulus cells were removed from in vitro matured oocytes either before or after IVF. The presence of cumulus cells during IVF did not affect final cleavage or development rates. In a second experiment, in vitro matured oocytes were fertilized in the presence of cumulus cells and cultured in SOFaaBSA medium alone or in the presence of ovine oviduct epithelial cell (oOEC) monolayer. Whereas, oviduct cells did not improve the cleavage rate, they significantly increased the rate of embryos reaching the blastocyst stage (from 3 to 25% of total oocytes). Ten blastocysts from oOEC coculture were transferred after freezing and thawing to five recipient hinds and gave rise to three pregnancies. The three pregnant hinds gave birth to three live and normal calves.

Animals↗

PubMed2003

Experimental infection of Black Belly and INRA 401 straight and crossbred sheep with trichostrongyle nematode parasites.

Compared to INRA 401 lambs reared in France, Black Belly (BB) lambs reared in Guadeloupe (F.W.I.) were highly resistant to both primary and secondary experimental infection with Haemonchus contortus. To investigate this huge inter-breed difference, a nucleus flock of BB was constituted, and experiments were conducted to: (i) confirm this difference in lambs born in France, (ii) check whether it was similar for Trichostrongylus colubriformis and Teladorsagia circumcincta, and (iii) find out whether this difference was age-related. Forty BB lambs, 84 F1 lambs (BB siresxINRA 401 ewes) and 88 INRA 401 lambs born in two cohorts were used in an experimental design involving three host breeds, both genders and two age-groups (3.5- and 7-month-old when first infected). The limited availability of BB lambs made the study incomplete. Infection consisted of the administration of two doses of 10,000 infective larvae of one of the nematode species, separated by an anthelmintic treatment and an interval of 1 week before the second dose was administered. Fecal egg counts (FECs) were done on Days 28 and 35 after each infection; ewe lambs of the INRA 401 and F1 breeds were necropsied, the worm burden was established, the length of the female worms measured and the eggs in utero counted. For H. contortus and T. colubriformis, the FEC was lower in the BB than in the INRA 401 lambs, and the FEC found for the F1 lambs was intermediate. For T. circumcincta, only data for the F1 and INRA 401 lambs were available, and the FECs for these breeds were the same. In all three breeds, the FEC determined after the second dose was significantly lower than that found after the first dose in the ewe lambs, but not in the ram lambs. Infecting the lambs when they were 7- instead of 3.5-month-old significantly lowered egg excretion of both parasites in the F1 (P<0.0001), but not the INRA 401 lambs. Worm numbers in the F1 and in the INRA 401 ewe lambs confirmed the FEC data, many F1 lambs being free of T. colubriformis. The H. contortus female worms were shorter and had fewer eggs in utero in the F1 than in the INRA 401 lambs. A higher proportion of T. circumcincta was at the fourth larval stage in the F1 lambs. In conclusion, the BB breed is much more resistant than INRA 401 to H. contortus, with the F1 lambs being more like the BBs after the second dose. This difference was also found for T. colubriformis and, to a lesser extent, for T. circumcincta.

Age Factors↗

PubMed2003

Current status of embryo technologies in sheep and goat.

This review presents an overview of the technical bases of in vivo and in vitro embryo production in sheep and goat. The current limitations of in vivo production, such as variability of response to the hormonal treatment, fertilization failure in females showing a high ovulatory response, and the importance of premature regressed CL in the goat, are described along with possibilities for improvement. The new prospects offered by in vitro embryo production, by repeated ovum pick-up from live females and by juvenile breeding, are presented along with their limiting steps and research priorities. The recent improvements of embryo production and freezing technologies could be used for constitution of flocks without risks of disease transmission and will allow wider propagation of valuable genes in small ruminants populations in the future.

Animals↗

PubMed2001

Successful direct transfer of vitrified sheep embryos.

The use of a simple cryopreservation method, adapted to direct transfer of thawed embryos may help to reduce the costs of embryo transfer in sheep and increase the use of this technique genetic improvement of this species. Two experiments were made to test a vitrification method that is easy to apply in field conditions. All embryos were collected at Day 7 of the estrous cycle of FSH-stimulated donor ewes and were assessed morphologically, washed in modified PBS and incubated for 5 min in 10% glycerol, for 5 min in 10% glycerol and 20% ethylene glycol and were transferred into the vitrification solution (25% glycerol and 25% ethylene glycol). All solutions were based on mPBS. Embryos were loaded in straws (1 cm central part, the remaining parts being filled with 0.8 M galactose in mPBS) and plunged into liquid N2 within 30 sec of contact with the vitrification solution. The straws were thawed (10 sec at 20 degrees C) and the embryos were either transferred directly or after 5 min of incubation in the content of the straw (followed by washing in PBS) into the uterus of a recipient ewe. In Trial 1, the pregnancy rates at term (72 vs. 72%) as well as the embryo survival rates (60 vs 50% respectively) were not different between fresh (n = 48 embryos) and vitrified (n = 50) embryos. In a second trial no difference was observed between vitrified embryos transferred after in vitro removal of the cryoprotectant (n = 86 embryos) or directly after thawing (n = 72) both in terms of lambing rate (67 vs. 75%, respectively) and embryo survival rate (lambs born/embryos transferred; 49 vs. 53%). This method of sheep embryo cryopreservation provided high pregnancy and embryo survival, even after direct transfer of the embryos.

Animals↗

PubMed2001

Mutation in bone morphogenetic protein receptor-IB is associated with increased ovulation rate in Booroola Mérino ewes.

Ewes from the Booroola strain of Australian Mérino sheep are characterized by high ovulation rate and litter size. This phenotype is due to the action of the FecB(B) allele of a major gene named FecB, as determined by statistical analysis of phenotypic data. By genetic analysis of 31 informative half-sib families from heterozygous sires, we showed that the FecB locus is situated in the region of ovine chromosome 6 corresponding to the human chromosome 4q22-23 that contains the bone morphogenetic protein receptor IB (BMPR-IB) gene encoding a member of the transforming growth factor-beta (TGF-beta) receptor family. A nonconservative substitution (Q249R) in the BMPR-IB coding sequence was found to be associated fully with the hyperprolificacy phenotype of Booroola ewes. In vitro, ovarian granulosa cells from FecB(B)/FecB(B) ewes were less responsive than granulosa cells from FecB(+)/FecB(+) ewes to the inhibitory effect on steroidogenesis of GDF-5 and BMP-4, natural ligands of BMPR-IB. It is suggested that in FecB(B)/FecB(B) ewes, BMPR-IB would be inactivated partially, leading to an advanced differentiation of granulosa cells and an advanced maturation of ovulatory follicles.

Amino Acid Sequence↗

PubMed2001

Successful in vitro production of embryos in the red deer (Cervus elaphus) and the sika deer (Cervus nippon).

The aim of our study was to define the conditions for IVM and IVF of oocytes in 2 common deer species as models for endangered related subspecies. Immature oocytes were recovered during the breeding season from postmortem ovaries (red deer) or by repeated laparoscopic follicular aspiration (sika deer). Oocytes were cultured for 24 h in IVM medium supplemented with EGF or FSH and follicular fluid. Stag semen was collected by electroejaculation (both species) or by epididymal flushing (red deer) and cryopreserved. For IVF, oocytes were exposed to different concentrations of thawed spermatozoa in a modified Tyrode albumin lactate pyruvate medium supplemented with 20% (v/v) estrus sheep serum for 18 h. After IVF, presumptive zygotes were allowed to develop in vitro for 7 days in synthetic oviduct fluid (SOF) supplemented with fetal calf serum (10%, v/v). In both species, the presence of ovine FSH and follicular fluid improved the in vitro maturation rate. In the sika deer, the optimal sperm concentration for IVF was 10(6)/mL and some fertilized oocytes reached the early morula stage (20 to 25 cells). In the red deer, after IVF with ejaculated or epididymal spermatozoa (2.0 x 10(6)/mL), 20% of zygotes developed to the blastocyst stage (50 to 80 cells).

Animals↗

PubMed2000

Effect of growth factors, EGF and IGF-I, and estradiol on in vitro maturation of sheep oocytes.

The objective of these experiments was to determine the effect of exogenous addition of insulin-like growth factor-I (IGF-I, 100 ng/mL), epidermal growth factor (EGF, 10 ng/mL) and estradiol (E2, 100 ng/mL) to the maturation medium of sheep oocytes on their subsequent development in vitro. Addition of IGF-I to the maturation medium did not improve nuclear or cytoplasmic maturation of sheep oocytes at the concentration tested. However, EGF improved significantly the resumption of meiosis (84% oocytes in metaphase II stage after IVM vs. 59% in medium alone). Cleavage rate and blastocyst development rates were improved (P<0.01) after addition of EGF (60% and 29%, respectively), as compared with maturation in TCM 199 alone (39% and 19%, respectively), but remained lower than rates observed after maturation in complete medium containing follicular fluid (FF, 10%) and FSH (81% and 35%, respectively). No additive effect of EGF over FSH was observed during these experiments. Addition of FF to FSH containing maturation medium improved significantly both cleavage (P<0.001) and blastocyst rates (P<0.05). Addition of E2 to the IVM medium is not required when medium already contains FF. However, in defined conditions supplementation of maturation medium with E2 had a positive effect. These results suggest that EGF, FSH and E2 may play an important role in the nuclear and cytoplasmic maturation of sheep oocytes in vitro.

Animals↗

PubMed2000

Effects of the Booroola Fec gene on ovarian follicular populations in superovulated Romanov ewes pretreated with a GnRH antagonist.

Endocrine control of follicular growth was studied in mature Romanov ewes carrying (RF+) or not carrying (R+2) the Booroola Fec gene during an oestrous cycle after gonadotrophin-dependent follicles were suppressed by treatment with an antagonist of GnRH (Antarelix, 0.5 mg per day) and superovulatory treatment was administered. The left ovary was removed after 10 days of treatment (saline or Antarelix) and the right ovary was removed at the end of the superovulatory treatment. Ewes of both genotypes treated with Antarelix had lower plasma LH concentrations than did controls from day 0 to day 10. The inhibitory effect of Antarelix on LH concentration increased with day of treatment. The variability in FSH concentrations during the initial 10 days was reduced by Antarelix treatment in both genotypes. Plasma FSH concentrations were higher in RF+ ewes than in R+2 ewes. In both genotypes, FSH concentrations varied significantly with day of treatment, with the lowest concentrations at day 8 and the highest concentrations at day 5. RF+ ewes had a greater total and atretic number of antral follicles 0.62-1.12, 1.12-2.00 and 2.00-3.00 mm in diameter (classes 2, 3 and 4) than did R+2 ewes before and after superovulatory treatment. After superovulatory treatment, the total number of atretic and non-atretic follicles > 3.00 mm in diameter (class 5) increased in both genotypes. Superovulatory treatment also increased the number of total and atretic class 4 follicles in RF+ only. Conversely, superovulatory treatment decreased the mean number of class 3 follicles in both genotypes, while the number of atretic follicles was decreased only in R+2 ewes. Antarelix treatment significantly reduced the percentage of follicles > 2.00 mm in diameter in RF+ but not in R+2 ewes. Antarelix treatment before superovulatory treatment increased the total number of class 4 follicles in both genotypes but the increase was more significant in RF+ than in R+2 ewes. These results indicate that Antarelix pretreatment favours a greater superovulatory response in Romanov ewes carrying the Fec gene because ovulatory follicles are recruited from a wider range of follicular size classes.

Animals↗

PubMed1999

Aspects of follicular and oocyte maturation that affect the developmental potential of embryos.

The ability to mature, be fertilized and finally to develop into a viable embryo is acquired gradually by the oocyte during progressive differentiation throughout folliculogenesis. This process starts with oocyte growth during the first steps of follicular development. As the oocyte is close to its final size, other modifications occur, less spectacular but at least as important in determining the resulting ability of the oocyte to accomplish its reproductive purpose (developmental competence). These modifications, referred to as 'oocyte capacitation', are probably influenced by the follicle. The proportion of developmentally competent oocytes increases with follicular size. However, the relationship between follicular growth and oocyte competence is not very strict, since a given oocyte may acquire its competence at any stage of follicular growth and since some examples of functional disjunction between follicular size and oocyte competence are described. Follicular atresia may impair the acquisition of oocyte competence, as evidenced by the parallel study of follicular characteristics and of the developmental potential of their oocytes treated individually through in vitro maturation, fertilization and development. However, when atresia is experimentally induced in large preovulatory follicles, oocytes remain competent, indicating that once competence is acquired, it is no longer sensitive to atresia. Oocyte maturation represents only the end of this long and progressive process and validates the preparation of the oocyte by conferring its final developmental ability. As evidenced by recent cloning experiments, the cytoplasmic aspects of oocyte maturation are crucial for the acquisition of developmental competence. This cytoplasmic maturation may be activated in vitro by the use of complex media supplement (serum, follicular fluid) but the use of defined media for maturation allowed the identification of some active factors (such as epidermal growth factor, growth hormone, inhibin and activin). The study of some differential models of oocyte competence (follicular size and atresia, Booroola gene, prepubertal oocytes) will provide a better understanding of oocyte capacitation and maturation, and allow the improvement of in vitro methods for oocyte maturation, which represent the most limiting step of in vitro production of embryos in large mammals.

Animals↗

PubMed1996

The ovarian secretion of androstenedione and oestradiol during late pregnancy and the early postpartum period in sheep with an autotransplanted ovary.

During late pregnancy in the ewe, ovarian function is suppressed by placental steroids and following parturition ovarian function is restored. This experiment determined the ovarian secretion of oestradiol and androstenedione during late pregnancy and the early postpartum period in ewes. Six ewes with ovarian autotransplants were transplanted with three day 6 embryos and three gave birth on day 147. Ovarian and jugular blood sampled were collected on three different occasions. On each occasion a 4 h period of sampling was followed by a 6 or 8 h period during which the ewes were challenged with 150 ng of gonadotropin-releasing hormone (GnRH). Basal secretion of oestradiol and androstenedione was 0.3 +/- 0.1 and 10.5 +/- 3.0 ng min-1, respectively, on day 120 of pregnancy. Oestradiol secretion remained low on days 7 and 21 postpartum (0.4 +/- 0.3 and 0.3 +/- 0.1 ng min-1, respectively). Androstenedione secretion (ng min-1) on days 7 and 21 postpartum was 2.5 +/- 0.5 and 4.1 +/- 1.8, respectively. The injection of GnRH on day 121 of pregnancy produced luteinizing hormone (LH) release with a peak concentration of 0.6 +/- 0.1 ng mL-1, that did not stimulate steroid secretion. On day 8 postpartum GnRH injection induced LH release with a peak concentration of 3.9 +/- 1.1 ng mL-1 that stimulated secretion of oestradiol (0.2 +/- 0.1 to 2.1 +/- 0.9 ng min-1; P < 0.01) and androstenedione (2.3 +/- 0.6 to 17.1 +/- 6.9 ng min-1; P < 0.001). Similar effects were seen on day 22 postpartum; GnRH injection induced LH release with a peak concentration of 4.7 +/- 1.4 ng mL-1 that stimulated secretion of oestradiol (0.2 +/- 0.1 to 3.7 +/- 1.1 ng min-1; P < 0.001) and androstenedione (4.2 +/- 2.6 to 29.5 +/- 9.2 ng min-1; P < 0.01). These results suggest that the suppression of ovarian function during late pregnancy in the ewe is reversed by 7 days postpartum.

Androstenedione↗

PubMed1995

[Effect of progesterone on ovulation length and duration of the ovarian cycle induced by the male effect in the Barbarine ewe and the local Tunisian goat].

Two experiments were conducted on 30 Barbarine ewes (Exp 1) and 40 local Tunisian goats (Exp 2) in seasonal anoestrus (May). In both experiments, half of the females received 20 mg of progesterone intramuscularly just before male introduction (day 0). Blood samples were taken at 4 h intervals from the time of introduction of the ram, for the determination of the time of the preovulatory LH surge in response to the 'ram effect' (Exp 1) and once a day from days 1 to 8 to determine plasmatic progesterone concentrations (Exp 1, Exp 2). The ovulation rate was determined by coelioscopy at days 4 and 9, and oestrus behaviour was monitored twice daily in each experiment. In the ewe, progesterone delayed the time of the preovulatory LH surge (58.8 +/- 10.1 vs 20.5 +/- 10.7 h, P < 0.001), and suppressed hypofunctional corpora lutea (0/15 vs 7/14, P < 0.001). The induced ovulation rate was not significantly different between control and treated females (1.50 +/- 0.52 vs 1.26 +/- 0.46 respectively). Only 1 female in the control group and 2 in the treated group showed oestrus behaviour at the induced ovulation. Suppression of short cycles by progesterone treatment allowed synchronization of oestrus between days 17 and 20 compared to days 14 and 23 in the control group (P < 0.001). In the goat, all induced ovulations in the control group were followed by a short cycle. In the progesterone-treated group, 3 out of 20 goats developed abnormal induced corpora lutea (P < 0.001). First oestrus occurred between days 1 and 8 in control group and between days 2 and 3 in treated goats. Treatment with progesterone increased the percentage of females showing oestrus at induced ovulation (100 vs 35%, P < 0.001). The ovulation rate at first oestrus was increased in treated goats (1.85 vs 1.35, P < 0.001). In conclusion, 20 mg progesterone administered at day 0 is efficient at preventing the occurrence of short ovarian cycles. After ovulation induced by the male effect, the percentage of females in oestrus, and the induced ovulation rate are increased by progesterone treatment.

Anestrus↗

PubMed1993

[Control of terminal follicular maturation during the follicular phase in domestic mammals].

Terminal follicular maturation in the ovine and the bovine species involves growth and differentiation processes in follicles between 1-2 mm diameter and the preovulatory stage. During this maturation, the follicle acquires the ability to ovulate and the oocyte becomes able to be fertilized and to develop after fertilization. Selection of ovulatory follicles results from the integration of different parameters such as the circulating levels of gonadotropins, the structure of follicular populations and the sensitivity of the hypothalamo-pituitary axis to ovarian hormones. Differences between follicles for FSH and LH responsiveness can be amplified by paracrine intrafollicular regulations. These mechanisms are probably determinant for selection of ovulatory follicles.

Animals↗

PubMed1992

In vitro maturation and fertilization of goat oocytes.

Follicular cumulus-enclosed goat oocytes were matured in vitro in the presence of granulosa cells, follicle stimulating hormone (FSH), luteinizing hormone (LH) and estradiol-17beta. While 86% of the oocytes from follicles 2 to 6 mm in diameter achieved meiotic maturation, only 24% of the oocytes from follicles 1 to 2 mm in diameter progressed to Metaphase II. Exposure of follicle-enclosed cumulus-oocyte complexes to 20 degrees C prior to culture resulted in 11.5% of the oocytes exhibiting abnormal meiotic spindle. This indicated that immature goat oocytes are particularly sensitive to temperature. Ejaculated spermatozoa were capacitated according to the technique previously proposed for ram sperm (1). The fertilization rates of ovulated and mechanically denuded in vitro-matured oocytes were 85 and 82.8%, respectively; 59.7% of ovulated and 57.1% of in vitro-matured oocytes were normally fertilized, as shown by the presence of both the female and the male pronucleus as well as by the remnants of the sperm tail in the ooplasm, 17 hours after insemination. Polyspermy was the main abnormality detected, and it affected almost 20% of the inseminated oocytes. The cleavage rate (two to fourcell stage) 41 hours after insemination of in vitro-matured and fertilized oocytes was 58%.

Journal Article↗

PubMed1990

Resumption of gonadotrophin release during the post-partum period in suckling and non-suckling ewes.

The post-partum secretion of LH, FSH and prolactin was monitored in 15 suckling and 6 non-suckling Préalpes du Sud ewes lambing during the breeding season by measuring plasma hormone concentrations daily at 6-h intervals and also weekly at 20-min intervals for 6 h from parturition to resumption of regular cyclic ovarian activity. There was a constant phenomenon in the resumption of normal patterns of FSH and LH secretion: there was a rise in FSH values culminating on average on Day 4 post partum and returning subsequently to values observed during the oestrous cycle, and concurrently an increase in the frequency and amplitude of LH pulses more progressive in suckling than in non-suckling ewes which led to an elevation of LH mean concentrations and occurrence of an LH surge. Since neither the FSH secretory pattern nor FSH mean values differed between suckling and non-suckling ewes, the results suggested that LH pulsatile pattern was a major limiting factor for the resumption of normal oestrous cycles. Before regular oestrous cycles resumed other changes in preovulatory LH surges also occurred: (i) they increased in duration and probably in amplitude; (ii) they were preceded by an acceleration in LH pulse frequency and a large decrease in FSH values as in normal cyclic ewes; and (iii) at least in non-suckling ewes they occurred concurrently with a prolactin surge.

Animals↗

PubMed1987

Transfer of superovulated sheep embryos obtained with different FSH-P.

Embryo transfer is one way of accelerating genetic improvement in sheep. One of the main obstacles has been the production of good-quality embryos. The use of progestagens and the stimulation of ovulation with follicle stimulating hormone pituitary extract (FSH-P) has permitted the superovulation of donor and recipient ewes and the synchronization of their cycles. The injection of 16 mg FSH-P at the end of progestin treatment gave means of 9 +/- 1.5, 12 +/- 1.5, and 19.5 +/- 2.6 corpora lutea per ewes in the Préalpes, Lacaune, and Romanov x Préalpes breeds respectively (this last breed is particularly prolific). Twenty Préalpes donor ewes produced 133 embryos that were recovered surgically at Day 6 of gestation; of these, 99 morulae were transferable. Forty-five morulae transferred surgically into 24 Préalpes recipient ewes yielded 16 pregnant ewes and 27 lambs (1.7 per ewe). Twenty-two Lacaune ewes yielded 204 embryos, of which 152 morulae were transferable. Of 76 recipients, 58 became pregnant and gave birth to 97 lambs (1.7 per ewe). During anoestrus, the mean ovulation rate decreased from 11.2 to 8.4; 40.6% of the embryos recovered were of transferable quality versus 74.5% during the normal breeding season. An improved superovulation technique, based on the use of FSH-P with a known follicle stimulating hormone to luteinizing hormonal (FSH/LH) ratio, provided us with good-quality embryos. This treatment must be adapted to the season.

Journal Article↗

PubMed1987

Lamb production using superovulation, embryo bisection, and transfer.

In this study, 39 embryos from donor ewes superovulated with follicle stimulating hormone-pituitary (FSH-P) were bisected to produce pairs of monozygotic twin lambs for experimentation. Each pair obtained by bisecting 8-, 9- or 10-day-old embryos was immediately transferred surgically into a recipient ewe at the same physiological stage. Of the 39 recipients which received a pair of half-embryos by transfer into the uterine horn ipsilateral to the corpus luteum, 28 (72%) lambed. Eighteen of 28 recipients lambing (64%) produced pairs, i.e., 7 male and 11 female pairs. Ten of 28 lambings produced a single lamb, i.e., six males and four females. Overall yield (the number of lambs produced in relation to the number of embryos used) was 118%. This percentage tended to increase, depending on the day of collection (Day 8, 100%; Day 9, 118%; and Day 10, 131%).

Journal Article↗