Transfer Of Sheep Research Articles

Embryo transfer in sheep (Ovis aries), efficient and consistent framework in superovulation treatment

Embryo transfer in sheep (Ovis aries), efficient and consistent framework in superovulation treatment

PSIV-1 Effects of Poor Maternal Nutrition During Gestation on F0 and F1 Ewe Colostrum and Milk Composition and Colostrum Igg

Abstract High-quality colostrum and milk are critical for proper neonatal growth and immune system development. Immunoglobulin G (IgG) is the predominant antibody class in colostrum and is vital for passive immune transfer in sheep. There is limited understanding of how poor maternal nutrition during gestation (restricted- and over-feeding) might influence colostrum and milk composition and colostrum IgG concentrations and how F1 offspring colostrum and milk are impacted as a result of F0 maternal diet. The objective of this experiment was to determine if poor maternal nutrition during gestation impacts F0 and F1 colostrum and milk composition, including IgG concentrations. We hypothesized that maternal restricted-feeding would decrease, and maternal over-feeding would increase total solids, fat, and protein during early and transitional lactation and that restricted-feeding would increase IgG concentrations and over-feeding would decrease IgG concentrations in F0 and F1 ewe colostrum. Multiparous Dorset ewes pregnant (n = 46) with twins were fed 100% (control; n = 13), 60% (restricted; n = 17) or 140% (over; n = 16) of National Research Council (NRC) requirements. After birth and during lactation, dams were fed 100% NRC for lactating ewes, so the nutritional insult only occurred during gestation. Resulting ewe offspring (n = 32) were raised on control diets and were bred between 16 and 19 mo of age. Colostrum samples were collected within 24 h of parturition and milk samples were collected at d 3 and d 21 postpartum. Colostrum and milk composition were evaluated using Brix Refractometry (total solids, g/dL) and spectrophotometry (crude fat, %; crude protein, %). Additionally, a radial immunodiffusion assay was used to determine IgG concentrations (mg/dL) in colostrum. A treatment by time interaction was observed for F0 colostrum crude fat where restricted-fed ewes had less fat than control-fed ewes (P ≤ 0.024). No interaction was detected for all other F0 and F1 composition variables (P ≥ 0.16). We did not detect a main effect of diet on F0 or F1 total solids, crude fat, and crude protein of colostrum nor milk (P ≥ 0.24). A main effect of time was observed for all variables where colostrum had greater total solids, crude fat, and crude protein compared with milk at d 3 and d 21 (P ≤ 0.0001). No effect of maternal diet on IgG concentrations were detected in F0 or F1 ewe colostrum (P ≥ 0.46). These data indicate that poor maternal diet has minimal effects on F0 and F1 ewe colostrum composition and IgG concentrations, and d 3 and d 21 milk composition. In addition, the impact of F0 diet on colostrum fat composition did not persist into the F1 generation.

Small ruminant neonatal nutrition

Loss of preweaned lambs and kids is a significant economic burden on small ruminant enterprises. Nutrition is an impor­tant factor impacting neonatal losses. Four critical nutritional phases can impact neonatal viability: maternal gestational diet adequacy, colostrum feeding, milk feeding and rumen develop­ment, and post-weaning feeding practices. As with any farm animal, consumption of adequate amounts of high-quality co­lostrum is the single most critical event in the life of a small ruminant. In contrast to dairy cattle, no guidelines defining volume and immunoglobulin (Ig) content for sheep and goat co­lostrum to ensure adequate passive transfer are available. Simi­larly, there are no well-defined criteria for determining success or failure of passive transfer in sheep and goats. The second most critical event of the neonatal small ruminant is adequate rumen development to facilitate a smooth transition during the weaning process. This presentation will address these 4 nutri­tional phases with emphasis on colostrum management prac­tices and rumen development as methods to improve neonatal survivability and viability.

Multiple ovulation and embryo transfer in sheep: Effects of embryo developmental stage and quality on viability in vivo under farm conditions.

Multiple ovulation and embryo transfer (MOET) technologies are integral to genetic improvement programs in the sheep industries. Despite the protocols being well established, previous findings regarding the effects of embryo properties on MOET success remain contradictory. The objective of this study was to determine the effects of embryo developmental stage and quality on embryo viability following transfer to recipient ewes. Data including details of 377 embryos collected from 45 Merino donor ewes were obtained from MOET trials conducted on three separate farms on day 6 after laparoscopic artificial insemination (AI). A total of 270 embryos were classified as being of transferrable grade (grade 1: n = 233; grade 2: n = 37). One or two transferrable grade embryos were transferred to each of 256 synchronised recipient ewes and pregnancy diagnosis was performed on day 36 after embryo transfer. Embryos at the hatched blastocyst stage tended to have greater viability in vivo compared to embryos at the late morula stage (59.0 ± 10.6% vs. 36.2 ± 9.7%; P = 0.083). The viability of grade 1 embryos was greater than that of grade 2 embryos (53.6 ± 7.8% vs. 35.9 ± 10.2%; P < 0.05). The results suggest that the success of the MOET trials was influenced by the transfer of embryos at the late morula stage, almost half of which were classified as grade 2 embryos. These findings highlight the importance of following strict embryo quality grading criteria to inform the most economical management of recipient ewes and maximize pregnancy outcomes.

Towards Improving the Outcomes of Multiple Ovulation and Embryo Transfer in Sheep, with Particular Focus on Donor Superovulation.

Considerable improvements in sheep multiple ovulation and embryo transfer (MOET)protocols have been made; however, unlike for cattle, MOET is poorly developed in sheep, and thus has not been broadly applicable as a routine procedure. The tightly folded nature of the ewe cervix, the inconsistent ovarian response to various superovulatory treatments, and the requirement of labor to handle animals, particularly during large-scale production, has limited the implementation of successful MOET in sheep. Moreover, several extrinsic factors (e.g., sources, the purity of gonadotrophins and their administration) and intrinsic factors (e.g., breed, age, nutrition, reproductive status) severely limit the practicability of MOET in sheep and other domestic animals. In this review, we summarize the effects of different superovulatory protocols, and their respective ovarian responses, in terms of ovulation rate, and embryo recovery and transfer. Furthermore, various strategies, such as inhibin immunization, conventional superovulation protocols, and melatonin implants for improving the ovarian response, are discussed in detail. Other reproductive techniques and their relative advantages and disadvantages, such as artificial insemination (AI), and donor embryo recovery and transfer to the recipient through different procedures, which must be taken into consideration for achieving satisfactory results during any MOET program in sheep, are also summarized in this article.

Use of oxytocin to attain cervical dilation for transcervical embryo transfer in sheep.

The aim of this work was to determine whether a cervical dilation protocol (CDP) composed of only oxytocin can be used to perform transcervical (non-surgical) embryo transfer in sheep (NSET) without affecting the viability of the corpus luteum (CL). Likewise, we evaluated whether a cervical transposing test with a Hegar dilator (CT Hegar test), performed at oestrous time, could be used to screen ewes for NSET (greater or lower chances to transpose the cervix). For that, oestrous and ovulation synchronization was performed in 25 Santa Inês ewes to induce the dioestrous condition. Animals went through the following CDP in a crossover design: E+OX, oestradiol benzoate (100µg intravenously [IV]) and oxytocin (100IU IV); OX, oxytocin (100IU IV); and SAL, saline solution (IV). Using a Hegar dilator, cervical transposing attempts were performed at oestrous (D0) and dioestrous time (D8). The viability of the CL (morphology, luteal blood flow and progesterone values) was evaluated by ultrasonography (colour Doppler and B-mode) and by serum progesterone measurement from D7 to D13. The cervical transposing rate was lower for the SAL group (64%; 16/25; p<.05) and did not differ between the E+OX (88%; 22/25, p>.05) and OX (84%; 21/25, p>.05) groups. No treatment affected the CL viability. The CT Hegar test showed a high sensitivity (85.7%-93.3%), satisfactory accuracy (72%-84%), low false-negative rate (6.7%-14.6%), but high false-positive rate (46%-66.7%). In conclusion, a CDP protocol composed exclusively of oxytocin can lead to good cervical transposing rates and does not affect the viability of the CL. In addition, a screening test (CT Hegar) performed at oestrus can identify ewes for which cervical transposing will likely not occur at NSET.

PSI-30 Identification of fetal microchimerism in older ewes using qPCR

Abstract The presence of a male co-twin during pregnancy has been found to impact lifetime reproductive performance in the sibling ewe. XY chimerism, thought to originate from a male co-twin, has been observed in ewes, and may be associated with the rare development of freemartins. Fetal ram DNA has been observed in the maternal circulation during pregnancy, but it is unknown if this chimerism persists after parturition. The objective of this study was to determine if fetal male cells were present in soft tissues of older ewes and if so, does the occurrence differ with lifetime offspring sex ratio. Eight ewes approximately 7-years-old and having given birth to at least 71% female (n = 4) or 82% males (n = 4) were tested. DNA was extracted from 10 different tissues from each ewe (n = 80). In triplicate, real-time PCR (qPCR) was used to identify the presence of the SRY gene in each sample. Using the SRY primer pair, male DNA was identified in the brain (between 1.25 ng / µL and 125 pg / µL) and liver (between 125 and 12.5 pg / µL) from a ewe that had given birth to two males during her lifetime. If any additional male fetal DNA was present, it was below the detectable limits. In addition to giving birth to two males, this ewe was also born with two male co-siblings, thus the origin (sibling or offspring) of the male DNA is not known. These data suggest fetal cell transfer in sheep is possible and the frequency of fetal microchimerism is not associated with sex ratio of lifetime offspring.

Effects of serum starvation and ionomycin activation on the development of somatic cell nuclear transfer embryos in sheep

Synchronization of donor cells and activation of the reconstructed oocytes are important factors affecting the success rate in somatic cell cloning. In this study, it was aimed to investigate the effects of serum starvation in donor cell synchronization and ionomycin treatment in the activation of reconstructed oocytes after somatic cell nuclear transfer in Kivircik sheep. Cumulus cells were obtained from a slaughtered sheep ovaries and used as donor cells after serum starvation for 4 days (0.5% FCS; SS) or without serum starvation (10% FCS; S). After reconstruction, oocytes were activated by ionomycin for 5 min plus 6-dimethylaminopurine for 3 h (I+) or only with 6-dimethylaminopurine for 3 h (I-). All cleaved embryos (n= 44) at the second day of in vitro culture were transferred into synchronized recipient ewes (n= 10). Cleavage rates of the embryos were 37.3, 44.1, 34.6 and 44.7% in SS/I+, S/I+, SS/I- and S/Igroups, respectively. Recipient ewes had serum progesterone levels >1 ng/ml at 18 th day were 33.3, 50.0, 50.0 and 100.0%, respectively. Only one pregnancy in the S/I- group continued after 40 days however the cloned lamb (7.1%, regarding to embryos transferred) died 10 days before term due to a maternal problem (uterine torsion). The results of this study reveal that somatic cell synchronization by serum starvation and ionomycin treatment for the activation of oocytes can be omitted for the success of somatic cell nuclear transfer in sheep

84 Effect of Embryo Stage and Cryopreservation Method on Pregnancy Rates Obtained Following the Transfer of In Vivo-Derived Ovine Embryos on Small-Scale Farms in Thailand

Assisted reproductive technologies including superovulation, laparoscopic AI (LAI), and embryo transfer (ET) are important tools for genetic improvement in the sheep industry. The present study aimed to determine the effects of embryo stage and cryopreservation method on field trial outcomes of embryo transfer on small-scale farms in Thailand. Black Dorper ewes (n = 16) were used as donors and mixed breed ewes (n = 21) were used as recipients. Donors were superovulated as previously described (Tríbulo et al. 2012 Theriogenology 77, 1679-1685, 10.1016/j.theriogenology.2011.12.013) and inseminated by LAI within 22 to 24 h after standing heat (Day 0). Donors females were flushed on Day 2 to recover 2- to 8-cell embryos (n = 8) or on Day 6 to recover blastocyst-stage embryos (n = 8). Recovered embryos were randomly cryopreserved by either slow freezing or vitrification methods. Into 21 recipients was inserted an intravaginal device impregnated with CIDR® that was left in place for 10 days. Those received 300 IU of pregnant mare serum gonadotropin (PMSG) on Day 9 and randomly assigned to receive embryos on either Day 2 or 6 after oestrus. Two- to 8-cell embryos were thawed and transferred into the ipsilateral oviduct (n = 1-5 embryos/recipient) on Day 2. Five recipients received 15 slow-frozen embryos and 5 received 13 vitrified embryos. Blastocyst stage embryos were thawed and transferred into the ipsilateral uterine horn (n = 1-4 embryos/recipient) on Day 6. Five recipients received 11 slow-frozen embryos and 4 received 7 embryos. Pregnancy diagnosis was determined by ultrasonography 45 days after embryo transfer. Pregnancy rate was calculated as the proportion of ewes with at least one pregnancy out of the total number of ewes that received embryos. Chi-squared analysis was used to determine the effects of embryo freezing technique and embryo stage on pregnancy rate (SAS 9.2, SAS Institute Inc., Cary, NC, USA). All donor ewes responded to the superovulation program (donor had 3 to 6 corpora lutea). The mean number of viable embryos recovered was 4.3 ± 2.4 and 3.1 ± 3.7 for Day 2 and Day 6, respectively. Nineteen of the 21 recipient ewes responded to the synchronization program and received embryos in the study. There was no effect (P &gt; 0.05) of embryo stage (5/10 = 50% v. 3/9 = 33.3% for 2- to 8-cell v. blastocyst, respectively) or cryopreservation method (4/10 = 40% v. 4/9 = 44.4% for slow-freezing and vitrification, respectively) on pregnancy rate following embryo transfer. Results of the present study suggest that similar pregnancy rates following embryo transfer in sheep under tropical conditions in Thailand can be obtained using either 2- to 8-cell embryos or blastocyst-stage embryos and with embryos that have been cryopreserved by slow-freezing or vitrification. Further research with larger numbers of animals is necessary to confirm the preliminary results of the present study.

Role of catecholamines in maternal-fetal stress transfer in sheep

We sought to evaluate whether in addition to cortisol, catecholamines also transfer psychosocial stress indirectly to the fetus by decreasing uterine blood flow (UBF) and increasing fetal anaerobic metabolism and stress hormones. Seven pregnant sheep chronically instrumented with uterine ultrasound flow probes and catheters at 0.77 gestation underwent 2 hours of psychosocial stress by isolation. We used adrenergic blockade with labetalol to examine whether decreased UBF is catecholamine mediated and to determine to what extent stress transfer from mother to fetus is catecholamine dependent. Stress induced transient increases in maternal cortisol and norepinephrine (NE). Maximum fetal plasma cortisol concentrations were 8.1 ± 2.1% of those in the mother suggesting its maternal origin. In parallel to the maternal NE increase, UBF decreased by maximum 22% for 30 minutes (P < .05). Fetal NE remained elevated for >2 hours accompanied by a prolonged blood pressure increase (P < .05). Fetuses developed a delayed and prolonged shift toward anaerobic metabolism in the presence of an unaltered oxygen supply. Adrenergic blockade prevented the stress-induced UBF decrease and, consequently, the fetal NE and blood pressure increase and the shift toward anaerobic metabolism. We conclude that catecholamine-induced decrease of UBF is a mechanism of maternal-fetal stress transfer. It may explain the influence of maternal stress on fetal development and on programming of adverse health outcomes in later life especially during early pregnancy when fetal glucocorticoid receptor expression is limited.

Recombinant Adeno-Associated Virus-Mediated In Utero Gene Transfer Gives Therapeutic Transgene Expression in the Sheep

Somatic in utero gene therapy aims to treat congenital diseases where pathology develops in perinatal life, thereby preventing permanent damage. The aim of this study was to determine whether delivery of self-complementary (sc) adeno-associated virus (AAV) vector in utero would provide therapeutic long-term transgene expression in a large animal model. We performed ultrasound-guided intraperitoneal injection of scAAV2/8-LP1-human Factor IX (hFIX)co (1 × 10(12) vector genomes/kg) in early (n = 4) or late (n = 2) gestation fetal sheep. The highest mean hFIX levels were detected 3 weeks after injection in late gestation (2,055 and 1,687.5 ng/ml, n = 2) and 3 days after injection in early gestation (435 ng/ml, n = 1). Plasma hFIX levels then dropped as fetal liver and lamb weights increased, although low levels were detected 6 months after late gestation injection (75 and 52.5 ng/ml, n = 2). The highest vector levels were detected in the fetal liver and other peritoneal organs; no vector was present in fetal gonads. hFIX mRNA was detectable only in hepatic tissues after early and late gestation injection. Liver function tests and bile acid levels were normal up to a year postnatal; there was no evidence of liver pathology. No functional antibodies to hFIX protein or AAV vector were detectable, although lambs mounted an antibody response after injection of hFIX protein and Freund's adjuvant. In conclusion, hFIX expression is detectable up to 6 months after delivery of scAAV vector to the fetal sheep using a clinically applicable method. This is the first study to show therapeutic long-term hFIX transgene expression after in utero gene transfer in a large animal model.

Multiple Factors Affecting Superovulation in Poll Dorset in China

To expand the breeding flock of Poll Dorset sheep in China, multiple ovulation and embryo transfer breeding program was applied to the limited number of imported Australian Poll Dorset sheep. This study investigated the effects of FSH from three different manufacturers, parity (nulliparous vs multiparous), repeated superovulation, oestrus induction, corpus luteum regression and oestrus delay on Poll Dorset superovulation. The results showed that gonadotropin FSH from Canada Folltropin-V (Ca-FSH) was successfully used for superovulatory treatment with 160 mg-200 mg dosage per ewe and recovered 12.91 ± 7.80 embryos. Multiparous ewes for superovulation treatment were significantly better nulliparous ewes (p<0.05). The successive superovalution treatment reduced significantly embryo collection but did not affect transferable embryo number. Ewes with natural oestrus resulted in significantly higher number of embryos (13.83 ± 4.64) and of transferable embryos (12.00 ± 5.76) than ewes with induced oestrus (7.00 ± 4.92; 4.22 ± 3.42) and unknown oestrus cycle (5.94 ± 3.38; 3.19 ± 2.56, p<0.05). The delayed oestrus ewes at 24 h after superovulatory treatment produced significantly fewer embryos and transferable embryos (0.92 ± 1.51 vs 0.42 ± 0.90) than those with normal oestrus (p<0.01). Furthermore, the more transferable embryos were recovered from ewes with normal corpus luteum than those with corpus luteum regression (5.88 ± 5.09 vs 3.59 ± 4.30 and 8.83 ± 5.75 vs. 6.66 ± 5.41, p<0.01). These results suggest that in our farm practice, a comprehensive treatment method by using the Canadian FSH (Folltropin-V), plus choosing multiparous and natural oestrus ewes with normal corpus luteum might obtain an optimum embryo collection and embryos transfer in sheep.

92 CRYOTIPS: A SIMPLE VITRIFICATION TECHNIQUE FOR SHEEP AND GOAT EMBRYOS

Vitrification procedure for embryos has not been used massively because there is not a standard protocol according to species. We evaluated reproductive efficiency of vitrified embryos in plastic tips of micropipettes. Estrous cycles of 36 Criolla goats (donors, n = 10; recipients, n = 26) and 48 Merino sheep (donors, n = 10; recipients, n = 38) were synchronized by sponges containing 60mgof MAP (Progespon®). At sponge removal (goats, Day 18; sheep, Day 14), recipients received 200 UI of eCG (Novormon®, Syntex, Argentina). Sheep and goat donors were superovulated with a total of 80 (igpFSH (Folltropin V®, Bioniche, Canada) every 12 h in 6 decreasing doses (18, 18, 14, 14, 8, 8) during the last 3 days of progestagen treatment. A dose of eCG (200 UI, Novormon®) was applied at progestagen removal. Donors of both species were inseminated by laparoscopy with frozen/thawed semen (200 × 106 spz) 12 to 14h after the onset of estrus. Embryo recovery was done by surgical prepubic laparotomy, and uterine horns were flushed with PBS + 10% SFB at Day 8 after sponge withdrawal. Before vitrification, embryos were kept in commercial embryo holding medium (Syngro, Bioniche, USA) at 25°C. Vitrification solutions were prepared using holding solution (HS) contents, PBS + 20% FBS. Embryos were maintained at 25°C and processed according to the following procedures: (1) HS + 10% glycerol (G) for 5 min, (2) HS +10% G + 20% ethylene glycol (EG) for 5 min, and (3) HS + 25% G + 25% EG for 30 s. Embryos were aspirated in 1 μL of solution 3, into the center of a plastic micropipette tip (0.36 mm inner diameter), and plunged into a cryotube filled with liquid nitrogen. Before embryo transfer, tips were warmed with fingers for 10 s and immersed in 4 dilution steps during 5 min each with 2.5 mL of HS containing (1) 12.5% G+ 12.5% EG+ 0.5 M of sucrose (S), (2) 0.5 M S, (3) 0.25 M S, and (4) HS alone at 25°C. In both species, at Day 8 after sponge withdrawal, 2 embryos of similar stage were transferred. Under laparoscopy view, the tip of the uterine horn was exteriorized by a nontraumatic clamp, through a 1-cm-long midline incision. The embryos were placed into the uterine lumen after punction and the uterine horn was allowed to return to the abdomen (semi-laparoscopic technique). Pregnancy was diagnosed by ultrasonography (Aloka 500) at Day 28 after being transferred. Reproduction efficiency in both species is shown in Table 1. This technique proves to be simple and efficient for both ovine embryo stages but only for goat blastocysts and can be used by veterinarians in field conditions at a very low cost. Differences of morulae survival between species require further study. Table 1.Reproductive efficiency after vitrified/warmed embryo transfer in sheep and goats according to the embryo stage

Factors Determining the Risk of Inadvertent Retroviral Transduction of Male Germ Cells AfterIn UteroGene Transfer in Sheep

The possibility of permanent genetic changes to the germline is central to the bioethics of in utero gene therapy (IUGT) because of the concern of inadvertent potentially deleterious alterations to the gene pool. Despite presumed protection of the male germline due to early germ cell (GC) compartmentalization, we reported that GCs within the developing ovine testes are transduced at low levels after retrovirus-mediated IUGT, thus underscoring the need for a thorough understanding of GC development in clinically predictive models to determine the optimal time to perform IUGT and avoid germline modification. In the present studies, we used the fetal sheep model to analyze GCs for phenotype, location, proliferation, and incidence of transduction after IUGT at various fetal ages to learn when during development the nascent germline is likely to be at greatest risk of retrovirus-mediated alteration. Our studies show that although GCs were transduced at all injection ages, the levels of transduction varied by nearly 700-fold as a function of the age at transfer. After remaining largely quiescent as they migrated to/settled within nascent sex cords, GCs began active cycling before cord closure was complete, suggesting this is likely the point at which they would be most susceptible to retroviral transduction.Furthermore, we observed that compartmentalization of GCs continued into early postnatal life, suggesting the male germline may be vulnerable to low-level inadvertent retroviral vector modification throughout fetal life, but that this risk can be minimized by performing IUGT later in gestation.

Factors Determining the Risk of Inadvertent Retroviral Transduction of Male Germ Cells Following in Utero Gene Transfer in Sheep

Factors Determining the Risk of Inadvertent Retroviral Transduction of Male Germ Cells Following in Utero Gene Transfer in Sheep

Large-Scale Field Practice of Juvenile In Vitro Embryo Transfer in Sheep.

Large-Scale Field Practice of Juvenile In Vitro Embryo Transfer in Sheep.

Early Pregnancy Diagnosis by Serum Progesterone and Ultrasound in Sheep Carrying Somatic Cell Nuclear Transfer‐Derived Pregnancies

Early pregnancy diagnosis and monitoring play an important role following embryo transfer in sheep. The aims of the current study were to investigate (i) the pattern of serum progesterone profiles in sheep carrying somatic cell nuclear transfer (SCNT)-derived (clone) pregnancies, and (ii) the frequency of pregnancy loss during development following SCNT embryo transfer. Sheep SCNT embryos were made using standard nuclear transfer techniques. Day 7 embryos were surgically transferred to oestrus-synchronized recipients (n = 27). As a control, normal fertile ewes (n = 12) were bred by natural breeding. Serum was collected from all the ewes on the day of estrus (day 0 sample), 7 days post-estrus (day 7 sample) and 19 days post-estrus (day 19 sample) and every 10 days thereafter until lambing or pregnancy loss occurred. Serum progesterone (P4) was assessed using enzyme immunoassay. Pregnancy was confirmed by ultrasound scanning on day 35 of pregnancy followed by subsequent scanning every 10 days. In control ewes, pregnancy rate on day 35 was 83.3% (10/12), whereas in the ewes that received SCNT embryos, it was 22.2% (6/27; p < 0.05). The day 45 pregnancy rate in the control ewes was 83.3%, whereas in the SCNT embryo recipients it was 11.0% (p < 0.05). Hormone analysis revealed that SCNT embryo recipients exhibited a significantly lower P4 profiles at different time points in pregnancy compared to controls (p < 0.05). This study highlights the use of serum progesterone in combination with ultrasound for the investigation of embryo loss and crucial times during development of normal and SCNT embryos in sheep. Further, the serum P4 levels directly reflect the degree of placental development in these two groups.

Features of follicle-stimulating hormone–stimulated follicles in a sheep model: keys to elucidate embryo failure in assisted reproductive technique cycles

To evaluate the individual functionality of gonadotropin-stimulated preovulatory follicles, for understanding embryo failure in assisted reproductive technique cycles, in a sheep model. Observational, model study. Public research unit. Fifteen adult Manchega ewes. Synchronization of the estrous cycle with intravaginal progestagens and ovarian stimulation with FSH; evaluation of reproductive activity, plasma sampling, ovarian ultrasonography, and ovariectomies. Determination of estrus behavior, plasma and intrafollicular concentrations of E(2) and inhibin A, number and size of ovarian follicles, and developmental competence of oocytes. These results support the usefulness of serial measurements of plasma inhibin A for assessment of follicular growth during the FSH treatment, rather than of E(2) assays commonly used. Functionality of FSH-stimulated preovulatory follicles is clearly disturbed, as confirmed by a negative correlation between follicular size and intrafollicular concentrations of inhibin A and E(2) in preovulatory follicles after individual dissection; moreover, the ability of their oocytes to resume meiosis was diminished. Functionality of follicles in controlled ovarian stimulation (COS), and developmental competence of their oocytes, is disturbed by the high doses of gonadotropin supplied and finally determined by follicular sizes at starting FSH treatment.

Outbreak of sheep scab on two adjacent common alpine pastures in the canton of Schwyz (Switzerland)

Sheep scab, which is caused by the mite Psoroptes ovis, is a notifiable disease in Switzerland. In the framework of an epidemiological study in the canton of Schwyz, a sheep scab outbreak on 2 adjacent alpine pastures with 62 flocks (1770 sheep) was followed up clinically, parasitologically and serologically. No mass treatment of the flocks with organophosphates or avermectins had been undertaken before the flocks were taken up to the alpine pastures, but they were treated according to their serological status. Supervised treatment of seropositive judged flocks (at least one seropositive or at least 2 serologically equivocal animals per flock) with Doramectin was undertaken, whilst seronegative judged flocks remained untreated. Sheep returned from the summer pastures in early September 2001 and within three months scab infestation was diagnosed in 53 flocks (85.5%). These infested flocks were scattered all over the canton. Furthermore, the transfer of sheep from 6 infested flocks resulted in the transmission of the disease to 10 new flocks. Infested flocks were kept in quarantine and sanitized. The complexity of the traditional use of shared alpine pastures and the intense, uncontrolled trading with animals render the control of sheep scab difficult.

Multiple factors affecting the efficiency of multiple ovulation and embryo transfer in sheep and goats

This review offers an overview of the basic characteristics of in vivo embryo technologies, their current status, the main findings and the advances gained in recent years, and the outstanding subjects for increasing their efficiency. The use of superovulation and embryo transfer procedures remains affected by a high variability in the ovulatory response to hormonal treatment and by a low and variable number of transferable embryos and offspring obtained. This variability has been classically identified with both extrinsic (source, purity of gonadotrophins and protocol of administration) and intrinsic factors (breed, age, nutrition and reproductive status), which are reviewed in this paper. However, emerging data indicate that the main causes of variability are related to endocrine and ovarian factors, and so the number of studies and procedures addressing a better understanding and control of these factors may be increased in the future. The accomplishment of this objective, the improvement of procedures for embryo conservation and for the selection and management of recipient females, will allow further development and application of this technology.