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Epidermal growth factor (EGF) concentrations in the uterus show two peaks on days 2-4 and 13-14 during the estrous cycle in fertile cows. Loss of the two peaks has been linked to reduced fertility in repeat breeder cows. This study aimed to examine the effect of seminal plasma (SP) on normalizing endometrial EGF concentrations and restoring fertility in repeat breeder cows with low EGF concentrations on day 3. In study 1, we examined the effect of the deposition sites (the vagina and uterus) of SP on the endometrial EGF concentrations in repeat breeder cows. SP infusion into the vagina, but not uterus, on the first day of the estrus cycle (day 0) normalized the endometrial EGF concentrations (>= 4.7 ng/g tissue weight) on day 3. In study 2, the effect of SP volume (0.5 and 10 ml of SP and 0.5 ml of SP diluted to 10 ml) on EGF concentrations was examined. All groups with SP infusion had increased EGF concentrations on day 3, and cows with 10 ml of SP and 0.5 ml of SP diluted to 10 ml showed the highest levels of EGF concentrations. In study 3, we examined the effect of SP infusion on fertility. SP infusion normalized two peaks of endometrial EGF concentrations in about 60% of repeat breeder cows and produced more pregnancies than the controls (44.4 vs. 19.4%). Therefore, we concluded that SP may contain an activity to normalize the EGF profile and restore fertility in repeat breeder cows with altered EGF profiles.

The objective of the study was to compare the fertility after using sex-sorted or conventional semen either with oestrus detection (EST) or timed artificial insemination (TAI) in Holstein heifers. Holstein heifers were randomly assigned to one of the following treatments in a 2 × 2 factorial design. Heifers in the EST group were inseminated with sex-sorted (n = 114) or conventional semen (n = 100) after spontaneous or induced oestrus. Heifers in the TAI, subjected to the 5-day Cosynch+Progesterone protocol (GnRH+P4 insertion-5d-PGF2α +P4 removal-1d-PGF2α -2d-GnRH+TAI), were inseminated with sex-sorted (n = 113) or conventional semen (n = 88). Statistical analyses were performed using PROC GLIMMIX procedure of SAS 9.4 (SAS Institute Inc., Cary, NC). Overall P/AI was 60.7% for EST and 54.2% for TAI regardless of types of semen and 68.1% for conventional and 48.9% for sex-sorted semen regardless of insemination strategies. Fertility of heifers inseminated with either sex-sorted (53.5%; 44.2%) or conventional (69.0%; 67.0%) semen did not differ between EST and TAI respectively. Besides, the interaction between the semen type and the insemination strategy was not significant for P/AI. The embryonic loss was significantly greater with sex-sorted semen (17.1%) compared to conventional semen (1.6%). There was no sire effect with sex-sorted semen on P/AI (52.6% vs. 46.2%) and embryonic loss (16.4% vs. 18.0%). As expected, sex-sorted semen resulted in more female calves (89.8% vs. 51.6%) than conventional semen. Thus, sex-sorted semen can be used with 5-day Cosynch+Progesterone protocol to eliminate the inadequate oestrus detection and to increase female calves born in dairy heifers.

Zika virus (ZIKV) is an arthropod-borne virus (arbovirus) and is primarily transmitted byAedesspecies mosquitoes; however, ZIKV can also be sexually transmitted. During the initial epidemic and in places where ZIKV is now considered endemic, it is difficult to disentangle the risks and contributions of sexual versus vector-borne transmission to adverse pregnancy outcomes. To examine the potential impact of sexual transmission of ZIKV on pregnancy outcome, we challenged three rhesus macaques (Macaca mulatta) three times intravaginally with 1 x 107PFU of a low passage, African lineage ZIKV isolate (ZIKV-DAK) in the first trimester (~30 days gestational age). Samples were collected from all animals initially on days 3 through 10 post challenge, followed by twice, and then once weekly sample collection; ultrasound examinations were performed every 3-4 days then weekly as pregnancies progressed. All three dams had ZIKV RNA detectable in plasma on day 3 post-ZIKV challenge. At approximately 45 days gestation (17-18 days post-challenge), two of the three dams were found with nonviable embryos by ultrasound. Viral RNA was detected in recovered tissues and at the maternal-fetal interface (MFI) in both cases. The remaining viable pregnancy proceeded to near term (~155 days gestational age) and ZIKV RNA was detected at the MFI but not in fetal tissues. These results suggest that sexual transmission of ZIKV may represent an underappreciated risk of pregnancy loss during early gestation.

The embryonic mortality in cows is a growing concern for an ever-expanding dairy industry. The current study was an attempt to shorten the open period of dairy cows having suffered embryonic loss by diagnosing them at an earlier stage. The blood samples were collected from the Karan Fries (KF) cows on days 0 (day of AI/estrus), 4, 8, 12, 14, 16, 18, 21, 24, 28, 35 and 42 post insemination. The experimental animals were then categorized into pregnant (P), conception failure/early embryonic mortality (EEM) and late embryonic mortality cows (LEM), based on progesterone assay, ultrasonography and per-rectal palpation. There were 6 animals in each group. The plasma progesterone was higher in pregnant than EEM and LEM cows. Plasma Interferon-tau concentration was significantly (p0.05) lower in LEM than pregnant cows where it could be detected from day 14-21 but was non-detectable in EEM cows. The mRNA expression of ISG15, OAS1, MX1 and MX2 in blood neutrophils was significantly (p 0.05) higher from day 8-42 as against day 0 in pregnant cows. The highest expression was observed around day 18-21 in pregnant cows. The ISG15, OAS1, MX1 and MX2 mRNA expression was significantly (p 0.05) higher from day 4-42 as compared to day 0 in LEM cows, whereas in EEM cows the expression stayed close to that of day 0 (1.00 ± 0.00). The mRNA expression of ISG15, OAS1, MX1 and MX2 started to decline from day 24 onwards. The degree of expression of Interferon-tau stimulated genes was higher in pregnant and LEM cows than EEM cows. The study reveals that the Interferon tau stimulated gene expression in neutrophils can act as peripheral biomarkers for detecting the embryonic mortality in dairy cows.

The objective of this study was to elucidate the impact of parity on the efficiency of three different protocols to synchronize time of ovulation in Holstein cows. All cows enrolled in this trial were categorized into primiparous and multiparous (M 1 = 2–3 and M 2 ≥3 parities). Conception (P/AI at Day 28) and pregnancy (P/AI at Day 75) rates in the Presynch and CIDRsynch (31.7% and 35.5%; 26.3% and 28.4%, respectively) groups were significantly greater than that in spontaneous estrus (SE; 24.7 and 20.4%, respectively) group (P = 0.048 and 0.024; 0.041 and 0.011, respectively); however, no significant differences were detected between the SE and Ovsynch group for conception, pregnancy, and embryonic loss rates. Conception and pregnancy rates in the Presynch group decreased from 37.8% and 33.5%, respectively in primiparous cows to 29.6% and 23.1%, respectively in M 1 cows (P = 0.022 and 0.007, respectively). However, conception and pregnancy rates using the CIDRsynch regimen were increased from 31.1% and 23.8% in primiparous cows to 41.4% and 34.7% in M 1 cows (P = 0.017 and 0.008, respectively), and 40.9% and 33.6% in M 2 cows (P = 0.021 and 0.019, respectively). Embryonic loss rate using the CIDRsynch protocol was decreased from 22.9% in primiparous cows to 15.1% and 18.2% in M 1 and M 2 cows (P = 0.013 and 0.130, respectively). On the contrary, embryonic loss rate using the Ovsynch protocol was increased from 11.5% in primiparous cows to 22.1% and 21.8% in M 1 and M 2 cows (P = 0.001 and 0.003, respectively). The Cox proportional-hazards model of embryonic loss showed significant associations for parity and season of calving with the hazard of embryonic loss (P = 0.001 and 0.016, respectively). Multiparous cows (M1 and M2) had a higher risk of embryonic loss than primiparous cows (Hazard ratio = 1.32 and 1.89, respectively). Our results indicate that use of the CIDRsynch regimen may achieve satisfactory conception and pregnancy rates in multiparous Holstein cows. However, synchronizing time of ovulation in primiparous cows with use of the Presynch treatment increases the fertility indices.

BACKGROUND: In vitro embryo production (IVEP) is increasingly popular but data assessing the outcome of transferred embryos are scarce. OBJECTIVES: To determine the likelihood of pregnancy and embryonic loss after transfer of frozen-thawed IVP embryos and identify factors influencing success. STUDY DESIGN: Retrospective clinical study. METHODS: Blastocysts (n = 261) were produced from immature oocytes of Warmblood mares (n = 116) by Intracytoplasmic Sperm Injection (ICSI) and in vitro culture, and cryopreserved. Thawed IVP embryos were transferred into recipient mares on day 4, 5 or 6 after ovulation. The influence of donor mare (age, reproductive history), recipient mare (age, reproductive status, management; in-house versus outpatient, day post-ovulation), embryo (interval from ICSI to blastocyst formation) and management factors (season when Ovum Pick-Up was performed, year and method of transfer) on likelihood of pregnancy and embryonic loss was examined, and the developmental stage of the IVP embryo at the time of transfer was estimated. RESULTS: The percentage of mares pregnant 7-10, 23 and 37 days after transfer was 56% (147/261), 49% (129/261), and 48% (124/261), respectively. Development of IVP embryos after transfer equated to day 5 or 6 in vivo embryos. With the exception of year of transfer, none of the factors had an impact on the likelihood of pregnancy or embryonic loss. Nevertheless, the likelihood of pregnancy tended to be lower for IVP embryos from infertile mares or when embryos were transferred into recipient mares on day 6 after ovulation rather than on day 4 or 5. Finally, the diameter of the embryonic vesicle 7 days post transfer was lower for pregnancies that were lost compared to those that were maintained. MAIN LIMITATIONS: Small sample size in some of the donor and recipient mare categories. CONCLUSIONS: Cryopreserved IVP embryos should be transferred into recipient mares on day 4 or 5 after ovulation and a slower rate of post-transfer vesicle expansion indicates a higher risk of subsequent embryonic loss. This article is protected by copyright. All rights reserved.

After more than 20 years of use of preimplantation genetic tests for aneuploidies (PGS/PGT-A) there are still many problems related to the efficiency of this technique, most of them still without an adequate solution (Gleicher et al., 2018; Homer, 2019). From the clinical point of view, the benefits attributed to invasive PGT-A in the selection of euploid embryos remain controversial, especially due to the lack of scientific proof of its effectiveness in increasing live birth rates in various clinical situations, such as patients with advanced age, repeated implantation failures or recurrent miscarriages. In addition, evidence-based medicine also severely criticizes the rare randomized trials analyzing the clinical use of invasive PGT-A (Orvieto, 2016). If these criticisms were not enough, and undoubtedly one of the most important, it would be difficult to accurately assess the presence of embryonic mosaicism creating significant levels of false positive results, and worse, causing a real possibility of discarding healthy embryos. This makes the clinical application of PGT-A as a risky approach (Munne et al., 2017; Spinella et al., 2018). Another problem, not less important, would be the obligation to perform PGT-A by experienced embryologists, since otherwise the embryonic loss due to biopsy would be a frequent fact, something usually estimated below 10% but in some laboratories it may reach up to 30% of biopsied embryos (Munne, 2018). On the other hand, there are doubts about the future risks of invasive action of the usually 5-10 cell removed during biopsy for genetic diagnosis. Would there be repercussions for the health of these children? In animals, there are data suggesting that embryonic biopsies could be linked to changes in fetal neural tube or adrenal development (Wu et al., 2014; Zeng et al., 2013). Recently, Xu et al. (2016) described noninvasive chromosomal screening (NICS) by obtaining and sequencing free DNA dripped by embryos in the culture medium (without the need of embryo biopsy) creating a new non-aggressive and elegant perspective to preimplantation genetic diagnosis.

Lymphocytic foci (also known as lymphoid aggregates or tertiary lymphoid structures) form within the bovine endometrium after antigenic challenge. Their presence in the pregnant uterus provides evidence for a chronic inflammatory condition perhaps arising from an early postpartum uterine infection. The chronic inflammation that includes the foci could explain greater embryonic loss in dairy cows with early postpartum uterine disease. The objectives were to characterize the size and location of the foci in the pregnant uterus, determine their composition using immunohistochemistry, and associate their presence with the development of the pregnancy and embryonic loss. Pregnant cows (n = 43) were slaughtered on days 28, 35, or 42 of pregnancy. Uterine tissue was collected and processed for histologic and immunohistochemical analysis. The number of small (100 micron diameter), intermediate (100-250 micron diameter), and large (250 micron diameter) foci was counted. The number of cows averaging 0, 0.1 to 1, 1.1 to 2, and more than 2 foci per section (small, intermediate, and large; combined) was 7 (16%), 14 (33%), 11 (26%), and 11 (26%), respectively. The average number of small and intermediate foci found in the histologic sections was greater in cows with evidence of uterine infection postpartum (P 0.05). Lymphocytic foci were distributed within the caruncle and the intercaruncular tissue and comprised a core of CD3-positive cells (T cells) surrounding CD79-positive cells (B cells). The number of lymphocytic foci was correlated with a total inflammation score (on the basis of the total number of inflammatory cells in the endometrium; r(2) = 0.49; P 0.001) and a fibrosis score (based on the extent of fibrosis in the endometrium; r(2) = 0.33; P 0.001). Cows with a high foci count (averaging more than 0.5 foci per section) had lesser (P 0.01) placental weight on Day 42 of pregnancy. There was no effect of foci count on placental weight on Day 28 or 35. Two cows with embryonic loss were in the highest quartile for foci count. In conclusion, cows with chronic inflammation as evidenced by a large number of lymphocytic foci had reduced placental weight during pregnancy. The number of foci in pregnant cows was associated with early postpartum uterine disease. Whether the foci themselves are inhibitory to pregnancy development or are associated with other bacteriological, morphological, or biochemical changes to the uterus that lead to infertility will need to be investigated.

This study evaluated the influence of artificial insemination (AI) by cervical retraction (CRI) on serum levels of interferon gamma (IFNγ) and interleukin-10 (IL-10) in ewes. Synchronized pluriparous Santa Ines ewes were subjected to natural mating (NM, n = 8) and AI, which was performed for a fixed time (55 ± 1 hour) by CRI (n = 8) or laparoscopy (n = 8). Ewes were classified as pregnant, with return to estrus (RE) or with embryonic loss (EL). Blood samples were collected on Day 0, Day 3, Day 5, Day 12, and Day 17 (Day 0 = AI/NM) for progesterone dosage and cytokines were quantified from Day 0 to Day 12. Progesterone levels were constant, except for a decrease in ewes with RE at Day 17 (P

To investigate the effect of uterine space on timing of embryonic mortality, multiparous sows were left intact (CTR; n=42) or subjected to unilateral oviduct ligation (LIG; n=23), after their first post wean oestrus. Intact sows were killed at day 9 (n=10), day 21 (n=15), or day 35 (n=17), and LIG sows were killed at day 21 (n=11) or day 35 (n=12) of gestation. At day 9, 92% of ovulations were represented by an embryo. At day 21, embryonic mortality was 24% and was not altered by increasing uterine space. At day 35, space per embryo was twice as large in LIG sows (30±3 v. 16±0.8 cm), and implantation length tended to be larger (19.0±1.2 v. 15.5±1.3 cm). Between day 21 and day 35, CTR sows lost another 8% to 14% of their embryos, whereas LIG sows lost none. Embryos tended to be heavier (4.9±0.2 v. 4.3±0.3 g) in LIG sows. In conclusion, embryonic loss in multiparous sows is 24% by day 21 and is not related to space, whereas after day 21 limited space causes additional 8% to 14% embryonic mortality in intact sows only.

Embryonic loss in cattle may be related to a hormonal imbalance resulting in alterations in timing of prostaglandin F2α (PGF2α) secretion around the time of maternal recognition of pregnancy. The objective of this study was to examine effects of aspirin (a PGF2α inhibitor) on pregnancy per AI (P/AI), and progesterone (P4), and pregnancy specific protein B (PSPB) concentrations in lactating dairy cows inseminated more than once after parturition. Fourteen days after second or subsequent AI (Day 0 = Day of AI), 556 cows were assigned randomly to aspirin (187.2 g total; n = 277) or control (n = 279) groups. Aspirin was administered orally on Day 14 and 15, and control cows were subjected to sham bolus administration. On Day 25, blood samples were collected from a subset of cows (n = 194) to quantify P4 and PSPB, whereas pregnancy was determined in all cows at 35–42 days post-AI. Maximum daily ambient temperature ranged from 38-41 °C during the experiment. Mean parity, days in milk, and times bred before treatment (TBRD) did not differ between groups. There were no differences in P/AI between treatments (aspirin 21.6 % compared with control 27.5 %). Neither treatment, parity, TBRD, or any two-way interactions with treatment affected concentrations of P4. Moreover, there were no effects (P > 0.50) of treatment, or treatment by TBRD interaction on serum PSPB concentrations. A tendency (P = 0.07) occurred for multiparous cows to have greater serum PSPB concentrations compared with primiparous cows. Mean serum PSPB concentrations tended (P = 0.07) to be greater for second or third TBRD compared to fourth and greater TBRD. These results provide evidence that aspirin administered during periods of heat stress after the second and subsequent AI post-partum during the summer months does not improve P/AI or alter P4 and PSPB in lactating dairy cows.

Objectives were to determine relative ovary location of follicles, GnRH-induced corpora lutea (CL), and older CL present in ovaries as part of ovulation synchronization and their associations with progesterone concentration and risk for luteolysis, ovulation, and pregnancy. Cows were exposed to a timed artificial insemination (AI) program [GnRH-1-7 d-PGF2α (1 dose or 2 doses 24 h apart)-56 h after first or only dose of PGF2α-GnRH-2-16 h-timed AI at 72 ± 3 d in milk]. Blood was collected to assess progesterone when ovarian structures were mapped in 694 cows before GnRH-1 and before and 48 h after PGF2α and, in a subset of cows, size of CL (n = 599) and progesterone (n = 380) at 6 d after AI. Dominant follicles and CL in single-ovulating cows were detected more often in right than left ovaries (follicles before GnRH-1: 60.6% right and GnRH-2: 61.2% right; and CL before GnRH-1: 58.6% right and GnRH-2: 66.4% right). Dominant follicles in single-ovulating cows before GnRH-1 tended to be ipsilateral to the CL more often than contralateral (54.8 vs. 45.2%) with co-dominant follicles identified in both ovaries (19.3%). In response to GnRH-1 or GnRH-2, more left-ovary follicles ovulated contralateral to CL (left to right, 54.7%; right to left, 34.7%) than right-ovary follicles, but fewer left-ovary follicles ovulated ipsilateral to CL (left to left: 45.3%) than right-ovary follicles ovulated ipsilateral (right to right: 65.3%). Preovulatory follicles in single-ovulating cows before PGF2α tended to be detected more often ipsilateral than contralateral to CL induced by GnRH-1 (younger CL; 56.5 vs. 43.6%), but were of equal frequency ipsilateral or contralateral to older CL present before GnRH-1. Luteolytic risk was less in cows bearing co-dominant follicles in both ovaries compared with those in either right or left ovaries. Luteolytic risk in single-ovulating cows did not differ between ovaries. Luteolytic risk was greater for cows bearing older CL (86.5%) than for cows bearing younger GnRH-1-induced CL (65.3%) or both (79.6%). Pregnancy risk at 60 d after AI was or tended to be greater in cows having both CL types compared with either younger or older CL, respectively, partly because of greater embryonic loss in the latter 2 cases. More female calves tended to be carried in right horns when conception occurred after first service, whereas the opposite greater female frequency occurred in left horns after repeat services. Right-ovary dominance is evident before and after GnRH treatment.

Background Pregnancy loss is a major source of infertility in dairy cows. Despite a fertilization rate after insemination (AI) of approximately 90%, calving rates are 30%–50%, indicating the occurrence of extensive embryonic and foetal losses. The aim of this study was to establish the extent and pattern of embryonic and foetal loss in Swedish Red (SR) and Swedish Holstein (SH) dairy cows, as well as, the relationship to oestrus intensity (OI) and progesterone (P4) concentration. In total, 2130 AIs and 16,176 milk P4 samples from 359 SR and 212 SH dairy cows were included in the study. Pregnancy losses were estimated using data from P4 values combined with AI information and calving data. Results Total pregnancy loss from AI to the day of calving was 65%. Early embryonic loss, late embryonic loss and foetal loss were estimated to be 29, 14 and 13%, respectively. There is strong evidence in the literature that P4 concentrations at different time points are associated with pregnancy loss. In the present study, cows with pregnancy losses had significantly higher P4 levels at the day of AI and significantly lower P4 concentration at days 10, 21 and 30 after AI compared to pregnant cows. Swedish Red cows had significantly lower total pregnancy losses compared to SH cows (62% and 68% respectively, P = 0.017). Early embryonic loss was 6.7% points lower for cows inseminated at a stronger OI (OI = 3) compared to at a weaker OI (OI = 2, P = 0.006). Cows inseminated at ovulation number ≥ 5 had significantly lower early pregnancy losses compared to cows inseminated at first or second ovulation (11.5 and 8% points, respectively, P

Equine embryos tolerate an unusually large degree of negative uterine asynchrony (recipient mare up to 5 days behind the donor mare). By contrast, positive asynchrony of more than 2 days results in a high incidence of early embryonic loss (EEL). Day 8 embryos range in diameter from approximately 130-1300 μm, with embryos smaller than 300 μm reported to suffer an increased incidence of EEL. However, it is not known whether this reduced viability is due to intrinsically poor embryo quality, or to inadvertent recipient uterine stage-embryo (positive) asynchrony. To examine whether small embryos survive better in Day 4-5 recipients than in recipients with a more advanced uterine stage, the likelihood of pregnancy (PR) and EEL for 62 small ( 0.1). The EEL for small embryos transferred into Day 4-5, 6-7 and 8-9 recipients was 20.8, 18.7 and 25.0%, respectively. We conclude that embryos recovered on Day 8 with a diameter

The main objective of the present study was to compare milk production in pregnant versus nonpregnant dromedary camels. In addition, we described the effect of embryonic mortality on lactation and measured serum progesterone levels until d 60 to 90 of gestation. Twenty-five multiparous camels were selected in midlactation for 2 studies in consecutive years. Camels were mated naturally when the size of the dominant follicle reached 1.2 to 1.5cm. Pregnancy was diagnosed by ultrasonography and progesterone determination. In the first experiment (Exp 1), 8 of 11 animals conceived at 284±21.5d postpartum. Three pregnant dromedaries were given PGF2α to induce luteolysis and pregnancy loss on d 62 and spontaneous embryonic loss was detected in 2 camels (on d 27 and 60). Animals were allotted to 3 groups retrospectively: nonpregnant camels (group 1, n=4), pregnant camels (group 2; n=3), and camels with embryonic loss after d 55 (group 3; n=4). In the second study (Exp 2), 14 dromedaries were mated during midlactation. Seven of them failed to conceive (group 1) and 7 became pregnant (group 2). No embryonic loss was detected in Exp 2. Turning points in milk production were identified by change point analysis. In nonpregnant dromedaries (group 1), milk decreased slowly over time without significant change point. In pregnant camels (group 2), a gradual decline until 4 wk after mating was followed by a sudden drop, and the change point model resulted in one breakpoint at d 28±7 and 35±3 of gestation in Exp 1 and Exp 2, respectively. In camels with embryonic mortality (group 3, Exp 1), milk yield started to decline similarly as in pregnant animals, but milk production increased gradually after embryonic loss and reached similar levels as in their nonpregnant herdmates. Change point analysis for group 3 resulted in 2 turning points at 30±4 and 48±4d after conception. Mean length of lactation was shorter by 230 (34.2%) and by 249d (37.6%) and mean total lactation production was decreased by 1,532 (31.6%) and 2,151 kg (44.3%) in pregnant compared with nonpregnant camels in Exp 1 and Exp 2, respectively. We concluded that the calving interval can be shortened by mating during midlactation. However, pregnancy has a strong negative effect on milk production as dromedaries stop lactating by the fourth month of gestation. Following embryonic mortality within 3mo of conception, milk production is restored.

The objective of this study was to elucidate the efficiency of Ovsynch protocol, new (N-CIDRsynch) and once-used (U-CIDRsynch) controlled internal drug-release (CIDR) devices to synchronize the ovulation time of primiparous and multiparous Holstein cows. The current study was performed on a total of 2207 cows using three different synchronized groups. Conception [pregnancy per AI (P/AI) at day 28] and pregnancy (P/AI at day 75) rates using the N-CIDRsynch and U-CIDRsynch regimens (35.9% and 29.6%; 29.2% and 25.1%, respectively) were significantly greater than those in the Ovsynch group [Odds ratio (OR)=1.88 and 1.44; 1.92 and 1.52, respectively]. Embryonic loss rate did not differ significantly (P>0.05) among the Ovsynch, N-CIDRsynch and U-CIDRsynch regimens. In primiparous cows, no significant differences were found in conception and pregnancy rates between the U-CIDRsynch and N-CIDRsynch groups (OR=0.95 and 1.12; p=0.693 and 0.451, respectively). In multiparous cows, conception and pregnancy rates in the N-CIDRsynch group were significantly greater than those observed in the U-CIDRsynch group (OR=0.66 and 0.71; p=0.016 and 0.027, respectively) and embryonic loss rate in multiparous cows was lower for the U-CIDRsynch treatment than for the N-CIDRsynch treated cows (COR=0.58; p=0.048). The present study indicates that the use of a progesterone device in a synchronization protocol may improve fertility in dairy cows compared to the Ovsynch treatment. The use of U-CIDRsynch regimen may achieve satisfactory fertility results compared to those reported with N-CIDRsynch in primiparous Holstein cows.

Early pregnancy loss occurs in 6–10% of equine pregnancies making it the main cause of reproductive wastage. Despite this, reasons for the losses are known in only 16% of cases. Lack of viable conceptus material has inhibited investigations of many potential genetic and pathological causes. We present a method for isolating and culturing placental cells from failed early equine pregnancies. Trophoblast cells from 18/30 (60%) failed equine pregnancies of gestational ages 14–65 days were successfully cultured in three different media, with the greatest growth achieved for cells cultured in AmnioChrome™ Plus. Genomic DNA of a suitable quality for molecular assays was also isolated from 29/30 of these cases. This method will enable future investigations determining pathologies causing EPL.

In our previous study (Tsuji et al., 2010 ), administration of hCG to recipients around the timing of implantation significantly increased the in vivo development of mouse embryos after somatic cell nuclear transfer (SCNT) until day 10.5, but did not increase the development to full term. The present study was undertaken to examine whether cotransfer of fertilized embryos or parthenogenetic embryos prevents the embryonic loss of SCNT embryos after day 10.5, allowing them to develop to full term. We found that compared with SCNT embryo transfer alone, full-term development of SCNT embryos slightly, but not significantly, increased by cotransfer of mouse hybrid blastocysts derived from BDF1 (C57BL/6×DBA) female×ICR male into the oviducts of recipients administered hCG (2.0% vs. 5.5%). This was not the case with the cotransfer of blastocysts from an ICR female×ICR male (2.5% vs. 2.2%) or parthenogenetic blastocysts from BDF1 female (3.0% vs. 2.0%). Furthernore, when SCNT blastocysts were transferred into the uteri of recipients, full-term development did not increase even with the cotransfer of hybrid blastocysts. The mechanisms of the effect of cotransfer of fertilized and parthenogenetic embryos on the full-term development of SCNT mouse embryos are discussed.

The impact of the 1918 influenza pandemic on human fertility has been subject to significant scholarly debate. The current study characterizes the inter-temporal association between excess deaths during the pandemic and the subsequent birth deficit by identifying the length of time between these two phenomena using cross-correlations of monthly death and birth data from Taiwan from 1906 to 1943. The analysis demonstrates a strong and negative correlation between deaths (d) at time t and births (b) at time t + 9 (r(db)(9) = -0.68, p < .0001). In other words, a significant drop in births was observed nine months after pandemic mortality peaked. The findings suggest that the 1918 influenza pandemic impacted subsequent births primarily through the mechanism of reduced conceptions and embryonic loss during the first month of pregnancy rather than through late-first-trimester embryonic loss.

Among embryos and neonates produced by pigs heterozygous for the reciprocal translocation rcp(13q-;14q+) were recovered: Preimplantation embryos: (1) From a heterozygous boar mated to 10 normal gilts, 109 embryos, 36 karyotyped (14 balanced normal, 11 balanced heterozygous, 11 unbalanced). (2) From a normal boar mated to 10 heterozygous gilts, 81 embryos, 33 karyotyped (10 balanced normal, 14 balanced heterozygous, 9 unbalanced). (3) From a heterozygous boar mated to 2 heterozygous gilts, 24 embryos, 11 karyotyped (2 balanced normal, 4 balanced heterozygous, 5 unbalanced). Postimplantation embryos: (1) From a heterozygous boar mated to 3 normal gilts, 19 embryos (7 balanced normal, 12 balanced heterozygous). (2) From a normal boar mated to 4 heterozygous gilts, 17 embryos (5 balanced normal, 10 balanced heterozygous, 2 degenerated). (3) From a heterozygous boar mated to a heterozygous gilt, 4 embryos (2 balanced heterozygous, 2 degenerated). Embryonic mortality estimated from numbers of corpora lutea and of living implanted embryos in heterozygous gilts mated with a normal boar, and in normal and heterozygous gilts mated with a heterozygous boar was 72.3 %, 68 %, and 85.5 %, respectively. The average litter size in the latter two types of matings was 7 and 5.1. The results are discussed in relation to meiotic behaviour, gametic products and embryonic mortality.

Cytogenetic analyses of horses have benefited the horse industry by identifying chromosomal aberrations causing congenital abnormalities, embryonic loss and infertility. Technical advances in cytogenetics enabled the identification of chromosome specific aberrations. More recently, advances in genomic tools have been used to more precisely define chromosome abnormalities. In this report we review the history of equine clinical cytogenetics, identify historical landmarks for equine clinical cytogenetics, discuss how the current use of genomic tools has benefited this area, and how future genomics tools may enhance clinical cytogenetic studies in the horse.

Contents Over a 25-month period 8118 blood samples were assayed for the presence of the serum pregnancy specific-protein B (PSPB) and progesteron (P4) concentrations on three Hungarian large-scale dairy farms. Pregnancy (n = 4085) was checked by BioPRYN assay at 30–36 days post-insemination (PI). Samples from all cows that tested not pregnant and from cows with an optical density (OD) reading in the BioPRYN test that was between 0% and 30% above the cutoff OD value were tested for serum P4 concentration. According to serum P4 concentration, cows were assigned to three categories: high (>4 ng/ml), medium (2–4 ng/ml) and low (

The objective of this study was to evaluate the impact of thermal stress on the efficiency of three different protocols to synchronize time of ovulation in purebred Holstein cows under subtropical Egyptian conditions. The influence of temperature humidity index (THI) on the conception, pregnancy, embryonic loss and early abortion rates were investigated. Conception and pregnancy rates using the CIDRsynch and Presynch (37.5% and 33.9%; 29.5 and 29. 6%, respectively) were significantly greater than that for cows expressing spontaneous estrus (SE) and with use of the Ovsynch (28.5% and 24.3%; 21.6% and 24.6%, respectively) treatment regimen. Conception and pregnancy rates using the Ovsynch protocol were significantly decreased from 31.6% and 26.3% at the lesser THI to 11.5% and 9.9%, respectively than at the greater THI [crude odds ratio (COR) = 0.28 and 0.32; P = 0.001 and 0.004, respectively]. However, conception (P/AI at 28 days) and pregnancy (P/AI at 75 days) rates using the Presynch protocol were significantly reduced at either the lesser or greater THI (COR = 0.47 and 0.42; 0.48 and 0.34, respectively). Embryonic loss rate with the Presynch group was significantly increased from 11.5% at the lesser THI to 22.2% at the greater THI (COR = 2.28; P = 0.039). In contrast, conception, pregnancy and embryonic loss rates did not differ significantly (P > 0.05) with the CIDRsynch protocol at the different THI. Results from the present study indicate that use of the CIDRsynch protocol may provide consistent and satisfactory conception and pregnancy rates in Holstein cows under subtropical environmental conditions.

Alpha-fetoprotein has proved to be a good indicator of fetal well-being in human medicine for decades. Although this molecule is present in most of the mammalian species including horses, reference values in healthy and high-risk pregnant mares have not yet been published. The aim of the present study was to determine whether equine alpha-fetoprotein (eqAFP) is a good indicator of complicated pregnancies in Lipizzaner mares. A total of 111 serum samples from 30 mares have been analyzed for eqAFP levels throughout gestation (Days 60-325). After the pregnancy was confirmed, 23 mares had normal pregnancies with viable foals, six had late embryonic loss, and one of the mares aborted in the ninth gestational month. Equine alpha-fetoprotein concentrations significantly differed in the normal group (72.93 ± 49.25 pg/mL; mean ± standard deviation) and in the complicated pregnancy loss group (152 ± 36.48 pg/mL; mean ± standard deviation). The mares' age, gestational age, and the conception rate significantly affected the alpha-fetoprotein concentrations in the normal group. Furthermore, notable individual differences occurred in eqAFP concentrations between mares. Equine alpha-fetoprotein seems to be an important indicator of fetal well-being in horses, but there are still some unanswered questions (levels in foals of different age, ponies, and draft horses) regarding this serum protein. Large-scale studies are needed to assess the specificity, sensitivity, and reliability of this test as a possible future diagnostic tool for fetal well-being in horses.

Purpose : To characterize the effects of ionizing radiation on the immature oocytes of prepubertal rats aged 16-20 days old. Materials and methods : The abdomen of Sprague Dawley (SD) female rats was exposed to 0, 1 and 2 Gy of X-rays. The effects were analysed when the animals became adults (80 days old) using as parameters the number of implantation sites, embryonic loss, dominant lethality and the synaptonemal complex (SC) analysis of F1 female foetuses. Results : A statistically significant decrease in the fertility of the 2 Gy irradiated rats was observed. However, the SC analysis of F1 female foetuses showed no cytogenetic damage that could be attributed to radiation. Conclusions : A reproductive effect was demonstrated but no inherited genetic damage was detected by SC analysis in female foetuses of irradiated mothers.

Reproductive tracts were collected from 870 ewes slaughtered at an abattoir in County Dublin over a 9-mo period from September 1993 to June 1994. Ovarian activity was evident in 59.3% of the tracts examined. The mean ovulation rate was 1.26 ± 0.045 (mean ± SEM). The spatial relationship between corpora lutea (CL) and dominant follicles was established. Ten percent of the ewes examined were pregnant. Embryonic transuterine migration was observed in 12% of the single ovulating ewes and in all ewes pregnant with twins which had double ovulations on one ovary. Based on the observation of tracts with contemporaneous double ovulations and a single fetus, the prevalence of embryonic loss was 17.2%. Overall, 9.4% of the tracts showed evidence of pathological change, and 5.5% of the tracts had abnormalities likely to impair fertility.

Poor reproductive efficiency is a worldwide problem that has affected the dairy industry during the last several decades. In an attempt to explain the changes in reproductive physiology caused by high milk production, a model of elevated steroid metabolism in lactating dairy cows has been proposed. A slow increase in levels and low peak levels of estradiol (E2) and progesterone (P4) characterize endocrine changes in high producing cows. Similar changes have been reported in the repeat breeder cows. The abnormal changes in E2 and P4 concentrations of these cows may cause an improper uterine environment due to disturbed expression of growth factors and cytokines in the endometrium. This review focuses on the alteration in epidermal growth factor (EGF) profile in the endometrium during the estrous cycle. The normal cow has two peaks of EGF concentrations on days 2–4 and 13–14. Low concentrations of EGF on these days distinguished both high-producing and repeat breeder cows from normal cows. Alteration of the EGF profile could be found in 70 and 40% of the repeat breeder and high-producing cows, respectively. Treatment with a high dose of estradiol benzoate and an intravaginal progesterone-releasing device restored the normal EGF profile in about 70% of the affected cows. The cows having a normal EGF profile after treatment showed a higher pregnancy rate than the cows with the altered profile. Further studies to understand the etiology of the alteration in the EGF profile are needed to develop another treatment option and preventive management for this problem.

The aim of this study was to evaluate the efficiency of presynchronization with GnRH and PGF(2 alpha) or with progesterone on overall Ovsynch (OVS) outcomes in noncyclic dairy cows. Cows were scanned 7 d apart with ultrasonography to determine cyclicity. Noncyclic cows (n = 281; no corpus luteum on ovaries at both examinations) were randomly divided into 3 groups. In the GP group (n = 108), the cows received GnRH and PGF(2 alpha) (PGF) administrations 7 d apart, and OVS was started 11 d after PGF (GnRH-7 d-PGF-11 d-OVS). In the P4 group (n = 90), the cows were treated for 7 d with an intravaginal progesterone (P4) implant (PRID), and then OVS was started 11 d after removal of the implant (7 d PRID-11 d-OVS). The control group (CON, n = 83) did not receive any presynchronization, and OVS was started at the same time as in the other groups (18 d-OVS). The percentage of cows that became cyclic at the beginning of OVS was lower in the CON group (38.6%; 32/83) than in the presynchronization groups (66.7%, 72/108 in GP; 71.1%, 64/90 in P4). The response to the first GnRH of OVS did not differ among groups (63.9%, 53/83 in CON; 67.6%, 73/108 in GP; 63.3%; 57/90 in P4), and synchronization rates were similar among the groups (74-82%). The cows that responded to presynchronization treatments (GP or P4) had higher pregnancy per artificial insemination (P/AI) than did nonresponding cows. Pregnancy per AI at 31 d did not differ between groups (30.1%, 25/83 in CON; 43.5%, 47/108 in GP; and 35.6%, 32/90 in P4). However, CON cows (24.1%, 20/83) had lower P/AI at 62 d than GP cows (41.7%, 45/108). Embryonic loss was higher in CON (20%, 5/25) compared with the P4 group (3%, 1/32). The administration of GnRH followed by PGF or exogenous progesterone (PRID) similarly increased the percentage of cows that became cyclic before Ovsynch in noncyclic cows, but fertility did not improve. However, the cows that responded to presynchronization had higher fertility rates than the nonresponding cows.

Mifepristone is a synthetic selective progesterone-receptor modulator (SPRM) that is widely used around the globe in the field of reproductive medicine. At present mifepristone is approved in a number of countries for early termination of pregnancy (TOP), cervical dilatation before surgical TOP, and management of early embryonic loss or fetal death. A number of new clinical applications are being developed in gynecology, endocrinology and oncology. Mifepristone has also served as an invaluable tool in the study of steroid hormone biology.Current indications for mifepristone are reviewed. New applications for mifepristone under clinical investigation are discussed. In addition, the unique molecular and cellular effects of mifepristone are described.The reader will understand the mechanisms of action of mifepristone and the underlying steroid hormone biology. The reader will know the approved clinical indications for mifepristone and appreciate the ongoing basic and clinical research into new applications.Mifepristone is the first-discovered and still most widely used antiprogestin. It has several indications in reproductive medicine and is under investigation for a variety of potential applications in other fields of medicine. The molecular and cellular effects of mifepristone illuminate important aspects of steroid hormone biology.

Purpose To establish in utero MRI-scanning of mouse implantation sites in a 1.5 Tesla whole-body human clinical scanner for evaluation of impaired implantation, placental or developmental defects due to genetic alterations. Materials and Methods Pregnant C57Bl/6 wild-type and Cx31-deficient mice revealing placental defects were analyzed in utero using a 1.5 Tesla whole-body clinical scanner in combination with a 3-cm-diameter single loop (slice thickness: 1.2 mm). Imaging of implantation sites was evaluated from 6.5–13.5 dpc and amount of implantation sites and in vivo development was analyzed during the critical phase of placentation from 10.5–13.5 dpc. Results This method provided high resolution in plane images permitting confident identification of all implantation sites from 6.5 dpc onward. A loss of 60% of Cx31-deficient embryos was demonstrated compared with controls. Repeated anesthesia as well as imaging protocols produced no gross malformations in the surviving mice. Conclusion Using a human clinical MRI scanner high resolution imaging of the entire uterus of the mice and all the embryos inside could be performed. This method is well suited to noninvasively monitor and quantify embryo implantation and to follow this dynamic process in vivo without compromising pregnancy progression and embryonic development. J. Magn. Reson. Imaging 2010;32:1158–1165. © 2010 Wiley-Liss, Inc.

Objective To evaluate the effect of progesterone during early pregnancy on pregnancy maintenance in mice. Design Experimental study or laboratory investigation. Setting An established molecular reproduction laboratory, Department of Biotechnology, S.V. University. Animal(s) Healthy virgin female Swiss albino mice of 8 weeks of age. Intervention(s) After confirmation of the heat period, adult female mice were mated with mature healthy males to achieve pregnancy. Inseminated females received intraperitoneal injections of progesterone at doses of 0, 1, 3.5, 7, 15, 25, or 50 mg/kg body weight on the first, third, and seventh day of pregnancy. Main Outcome Measure(s) Preimplantation embryonic loss. Result(s) Pregnancy failure was evidenced by reduction in the number of embryos in females injected with 7 (25.12 %), 15 (38.44 %), 25 (100%), and 50 (100%) mg progesterone/kg body weight. In females with a successful pregnancy, the numbers of corpora lutea and postimplantation loss per dam were comparable across all groups. No increase in the incidence of malformed fetuses was found in any progesterone-treated groups. Conclusion(s) Administration of supranormal levels of progesterone during early pregnancy caused a reduction in the number of implantations and an increase in preimplantation loss in mice.

Congenital malformations correspond to one of the main causes of embryonic loss during the gestational process. They result from interaction of several factors such as multifactor heredity, chromosomal and genetic alterations and environmental agents; however, unknown aetiology also can be present. In this article, we have used 10 embryos, from a frigorific area of Dracena, SP, Brazil, which were fixed in Bouin solution for a macro- and micro-scopic description. We could verify the presence of an encephalic tissue mass on the embryo's dorsal cranial area, resulting from the non-formation of part of the cranial cap and from the non-closing of cephalic neuropore and consequent neuroepithelial cells disorganization. In the abdominal area, the embryos did not show the complete fusion of the body lateral pleats during the abdominal wall formation, and the liver extruded into the amniotic cavity without involvement of the intestine.

Information is lacking as to the timing and cause of sows that repeatedly have low litter size over several parities. Sows evaluated for the present study had at least two parities either smallor=7 (SL) or normalor=12 (NL) litter size. Following breeding of sows with contemporary boars, reproductive tracts were obtained on day 30 of gestation. There was no difference (p0.10) between SL and NL sows in the number of CL, embryo weight or placental length. The total number of embryos and embryonic survival tended to be lower (p0.10) in SL sows compared with NL sows, but there were 5.1 less viable embryos (p0.03) in SL. Results indicate that time of conceptus loss in SL sows was variable throughout gestation.

A study on postpartum dairy cows was done to evaluate the effect of using progesterone intravaginal device (CIDR) to synchronize return to oestrus of previously timed inseminated (TAI) cows and to evaluate embryo survival and pregnancy rate in the return to oestrus cows. All cows were subjected to TAI program. On Day 14 after AI, cows were assigned randomly into two groups: treated group (CTAI; n=126) and control group (TAI; n=172). Every cow in the CTAI group received CIDR device for 7 days. Cows were observed for oestrus after CIDR removal in the first period (Days 21-28). Cows, which did not show oestrus, were retreated with CIDR on Day 28 for 7 days and they were observed for oestrus after CIDR removal in the second period (Days 35-42). Pregnancy was diagnosed on Days 28, 45 and 90 after AI. In the first period, more cows in the CTAI group showed oestrus within 2.4 days after CIDR removal compared to cows within 4 days in the control. In the second period, more cows in the CTAI group showed oestrus within 4.5 days compared to cows within 3.7 days in the control. Pregnancy rates on Day 28 were not different between both groups. Pregnancy rates on Days 45 and 90 were higher for cows in the CTAI (42.1+/-5.3%, P=0.028 and 38.9+/-5.2%, P=0.020) compared to that in the TAI group (35.5+/-3.9% and 31.9+/-3.8%). Moreover, pregnancy rates were lower for multiparous cows (34.2+/-4.1, P=0.017 and 30.2+/-3.9%, P=0.008) compared to primiparous cows (42.7+/-5.2% and 39.9+/-5.1%) on Days 45 and 90, respectively. Pregnancy losses between Days 28-45 and 45-90 tended to be lower for the CTAI group and primiparous cows compared to the TAI group and multiparous cows. Pregnancy rates of first (P=0.020), second, third and up to fourth AI were higher (P=0.001) for the CTAI group (38.9+/-0.05%, 78.6+/-0.05%, 92.1+/-0.04%, 93.6+/-3.71%) compared to that for the TAI group (31.9+/-0.03%, 54.1+/-0.04%, 68.0+/-0.03%, 81.4+/-2.75%, respectively). Days open for pregnant cows were similar in both groups, but lower (P=0.025) for primiparous cows (81.6+/-4 day) compared to multiparous cows (93.8+/-3 day). Number of services for pregnant cows was lower (P=0.002) for the CTAI group (1.70+/-0.10) compared to that for the TAI group (2.14+/-0.09), whereas it was similar for primiparous and multiparous cows. Results indicate that the CIDR device improved synchronization to return to oestrus and increased pregnancy rate to first, second, third and fourth AI by reducing embryonic and fetal losses.

Case-control studies on plurality dependent spontaneous embryonic loss rates after assisted reproduction found that twin pregnancies have a two to five times lower miscarriage rate of the entire pregnancy compared with singletons.

The new Italian law on assisted reproduction technology rules that no more than three oocytes can be fertilized at one time, and that all embryos obtained must be transferred to the maternal uterus simultaneously. The aim of the present study was to investigate the influence of the new law on spontaneous embryonic/fetal losses through comparison of data collected over an identical period of time: the first year of application of the new law compared with the same time period 1 year before (March 10, 2004 to March 9, 2005 versus March 10, 2003 to March 9, 2004). A total of 271 clinical pregnancies were analysed. In the post-law period, a significantly lower percentage of total spontaneous embryonic losses compared with the pre-law period, and a higher percentage of surviving embryos in singletons and twins was observed. In conclusion, the impact of the limitations imposed by the new legislation regulating assisted reproduction in Italy seems to exert positive effects on spontaneous embryonic loss both in singletons and multiple pregnancies. These findings are in contrast to international predictions on this issue and, in general, are counter-intuitive. This suggests that further investigations on a larger cohort of women are required to confirm these preliminary results.

Lactating Holstein cows (n = 711) on a commercial dairy farm in Wisconsin received a hormonal synchronization protocol to initiate first timed artificial insemination (TAI) on the following postpartum schedule: two injections of 25 mg PGF2alpha at 32 +/- 3 d and 46 +/- 3 d (Presynch); 100 microg GnRH at 60 +/- 3 d; 25 mg PGF2alpha at 67 +/- 3 d; and 100 microg GnRH + TAI at 69 +/- 3 d (Ovsynch). At first TAI, cows were randomly assigned to initiate the first GnRH injection of a hormonal protocol for resynchronization of ovulation (Resynch; 100 microg GnRH, d 0, 25 mg PGF2alpha, d 7, 100 microg GnRH + TAI, d 9) at 19 (D19), 26 (D26), or 33 d (D33) after first TAI to set up a second TAI service for cows failing to conceive to Ovsynch. Overall pregnancy rate per artificial insemination (PR/AI) to Ovsynch assessed 68 d after TAI was 31% and did not differ among treatment groups. For Resynch, PR/AI was assessed 26 d after TAI for D19 and D26 cows and 33 d after TAI for D33 cows. Overall PR/AI to Resynch was 32%. However, the PR/AI for D26 (34%) and D33 (38%) cows to Resynch was greater than for D19 cows (23%). Cows with a CL at the PGF2alpha injection (D19 cows) or at the first GnRH injection (D26 + D33 cows) of Resynch exhibited greater PR/AI to Resynch compared with cows without a CL. Survival analysis (failure time) of cows in the D26 and D33 treatment groups across the first three TAI services did not differ statistically. Although administration of GnRH to pregnant cows 19 d after first TAI service did not appear to induce iatrogenic embryonic loss, initiation of Resynch 19 d after first TAI service resulted in a lower PR/AI compared with initiation of Resynch 26 or 33 d after first TAI service.

Epidemiological studies on male mediated developmental toxicity may focus on links between environmental exposure of the male and pregnancy failures or disorders in the offspring. Alternatively, the focus may be on biological markers of male fecundity and developmental disorders. The study design only rarely allows for a combination of these two approaches. Demonstration of effects of male exposure on the male reproductive system, and subsequent demonstration of links between observed abnormalities of the male system with abnormalities of foetal and childhood development in the offspring would provide strong evidence for causal associations between exposure and outcomes.

The effects of pre-ovulatory and post ovulatory insemination on pregnancy rate and embryonic-loss rate were studied in 268 mares in two experiments. Within each experiment mares were randomised within replicates as follows: to be inseminated on the day the pre-ovulatory follicle reached 35 mm (pre-ovulatory group), to be inseminated on the day of ovulation (Day 0 group), and to be inseminated on the day after ovulation (Day 1 group). Ultrasonic pregnancy diagnoses were performed on Days 11, 12, 13 and 14 (Experiment 1) and Days 11, 12, 13, 14, 15, 20 and 40 (Experiment 2). Combined for the two experiments, pregnancy rates were different (P less than 0.01) among the three groups. For Experiment 2, pregnancy rate within the pre-ovulatory group was lower (P less than 0.05) for insemination 4 days or more before ovulation than for up to 3 days before ovulation. Pregnancy rate was lower (P less than 0.05) for the Day 0 group than for the pre-ovulatory group inseminated up to 3 days before ovulation. In Experiment 2, ovulation was detected by examinations every 6 h; pregnancy rate was greater (P less than 0.05) for mares inseminated 0 to 6 h after ovulation than for mares inseminated at 18 to 24 h. No pregnancies occurred when mares were inseminated 30 h or more after ovulation. The mean day of first detection of the embryonic vesicle was different (P less than 0.0001) among the three groups. Diameter of embryonic vesicle averaged over Days 11 to 15 also differed (P less than 0.0001) among groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Plasma levels of LH and FSH before and after ovulation were measured in two rabbit strains (New Zealand A 1077 and Californian A 1066) having a different number of ovulations and rate of embryonic loss. Maximal concentrations and total secreted amounts before ovulation were slightly higher in New Zealand, but the difference was not significant. No relationship between the number of ovulations and the increase in plasma LH or FSH level was found in either strain. In most cases, there was no relationship between gonadotropic surge and early embryonic loss.

Fertilization rates were similar for normal and subfertile mares, and much of the difference in fertility between normal and subfertile mares was due to embryonic loss. Fertilization rate estimates for mares ranged from 71 to 96 per cent. The incidence of embryonic loss detected by ultrasonography between Days 11 and 50 was approximately 9 per cent for normal mares, and the estimated incidence of embryonic loss before Day 14 was also 9 per cent. Therefore, the estimated incidence of embryonic loss in normal mares between fertilization and Day 50 is approximately 18 per cent (Fig. 1). In subfertile mares, the corresponding estimate for embryonic loss between fertilization and Day 50 is 80 per cent, with most embryonic losses occurring before Day 14 in subfertile mares (Fig. 1). The high rate of early embryonic loss in subfertile mares could be related to embryonic defects, oviductal environment, or uterine environment. Oviductal embryos from subfertile mares were less viable than embryos from normal mares; therefore, embryonic defects were important in early embryonic losses in subfertile mares. These defects might be inherent within the embryo or might arise from the early oviductal environment. The uterine environment of subfertile mares was adequate to support normal embryos in early gestation; however, the relationship between the uterine environment and the increased metabolic demands of the conceptus in the late embryonic or early fetal periods requires further study. The uterine environment is also altered in mares with endometritis; therefore, endometritis may also be an important factor in embryonic loss in some mares. Uterine-induced luteolysis, as well as the effect of the pathogen or the resulting inflammation, may lead to embryonic loss. An increased susceptibility of some subfertile mares to endometritis could result in embryonic loss secondary to a postcoital endometritis that persists until the embryo reaches the uterus at Days 5 or 6 postovulation. Although progesterone is critical to embryonic survival, the cause-and-effect relationship between progesterone and spontaneous embryonic loss remains unclear. Reduced progesterone concentrations could be related to endometritis, failure of maternal pregnancy recognition, or luteal insufficiency. Progesterone supplementation may be indicated for some mares, but the value of exogenous progesterone for prevention of spontaneous embryonic loss has not been critically tested. A number of other factors have been associated with embryonic loss in mares.(ABSTRACT TRUNCATED AT 400 WORDS)

The fertilization rate and incidence of embryonic loss in virgin Brahman crossbred heifers between d 3 and 35 postinsemination (d 0 = first day of estrus) were determined. One hundred fifty-five virgin heifers, maintained in a dry lot, received approximately 22 Mcal.head-1.d-1 and were allotted to one of three groups (d 3, 16 or 35) according to body weight at the time of estrous detection. Seven empty ruptured zona pellucidae (ERZP) were recovered from five heifers in the d 3 group. It was impossible to determine whether the ERZP originated from fertilized or unfertilized ova and whether they were ovulated at the estrus immediately preceding or during a previous cycle. Consequently, the fertilization rate (d 3) was calculated to be 80 or 93% depending upon whether the ERZP were included or deleted from the calculations, respectively. Because of the large number of ERZP recovered, a second study was conducted with an additional 21 virgin Brahman crossbred heifers from which ova were recovered on d 3 postinsemination. The results of the two studies were similar. The percentage of heifers with an embryo on d 16 was 78 (10% had degenerating embryos and 12% no embryos), and the percentage pregnant at d 35 was 72. The conclusions suggested from this study depend upon the classification of the ERZP. If the ERZP are designated as ova ovulated during a previous cycle or ova damage in the collection process and are deleted from the calculations, the fertilization rate is high (93%), and embryonic loss apparently occurs between d 3 and 35 (P less than .95). However, if the ERZP are classified as ova ovulated at the immediately preceding estrus, unavailable for further embryonic development, and are included in the calculations, the fertilization rate is comparatively low (80%). In the latter case, the primary loss of potential embryos occurs before d 3, and the loss after d 3 is negligible (P greater than .05).

The chromosome complement and anatomical development of 10–16-gday rabbit embryos were studied following delayed fertilization. Preimplantation loss was 40% in the experimental group compared with 17% in control animals. Also, a greater number of embryos retarded in growth or with structural anomalies was seen in the delayed-mated group. Cytogenetic analysis revealed a trisomy for a small metacentric chromosome in 104 control embryos. Only 1 triploid embryo was found in 84 implantation sites from rabbits that had been delayed mated. The incidence of triploidy postimplantation was much less than the 13% found previously in 6-day blastocysts. Increased embryonic loss at the time of or shortly after implantation may be responsible for the discrepancy.

A single oral dose of mestranol (l7ct-ethynylestradiol 3-methyl ether) was administered to two groups of eight adult female beagle dogs each on Day 6 or 21 after first acceptance of the male. Based on corpora lutea counts, embryonic loss was 95.5 and 67.3%, respectively, for the two treatment groups, and only 34.5% for the control. In a second study a group of 12 beagles were used to determine the effect of mestranol on ova transport. Nine bitches were dosed on Day 6 and the reproductive tracts were removed between 1 and 5 days later and three controls were examined on Day 11. Thirty-nine of a possible 56 ova were flushed from the tracts of the treated females and all but one were from the oviducts. Eighteen (46%) of the ova were degenerating. The controls produced 17 normal zygotes out of a possible 24, and all were flushed from the uteri. Mestranol apparently did not accelerate ova transport, and the possibility of both a direct effect on the ova and an indirect effect via a delay in ova transport is discussed.

Normal pregnant guinea pigs were killed on gestation days 12–20 and examined for implantation sites and resorbing embryos. Their ovaries were removed and serially sectioned, and the functioning corpora lutea counted for comparison with the number of conceptuses. It was found that a single corpus luteum was associated with two implantation sites with a frequency of 9.55%. Embryonic loss prior to implantation was 12.6% and the value for resorption following implantation varied from 5.8 to 7.2% depending on the time of killing and the method employed for determining resportion. A count of functioning corpora lutea facilitated the determination of embryonic loss prior to implantation, but offered little advantage over simpler techniques for determining resorption after implantation.

Methyl chloride (MeCl) is a testicular and epididymal toxicant in the Fischer 344 rat that induces significant decreases in sperm quality in males and significant increases in preimplantation embryonic loss in females mated to exposed males. This study examined the possibility that these losses are due to failure of fertilization and not to preimplantation embryonic death. Groups of males either were exposed to 1000 or 3000 ppm MeCl 6 hr/day for 5 days or received a single ip injection of 0.2 mg/kg triethylenemelamine (TEM) on Day 5 and were bred to two females weekly for up to 8 weeks. Females were killed 12 hr postmating; embryos and ova were isolated and scored as fertilized or unfertilized. Nearly 90% (602/683) of the normal ova recovered from females bred to control males were fertilized, and fertilization rates in the 1000-ppm MeCl and TEM groups were not significantly depressed from that level. The percentage of fertilized ova in the 3000-ppm MeCl group was significantly decreased, ranging from 3 to 72% over the 8 weeks. The frequency of unfertilized ova in this group always equaled or exceeded the frequency of preimplantation loss recorded in an earlier dominant lethal assay. In contrast, only a fraction of the preimplantation losses caused by the genotoxicant TEM could be accounted for by failure of fertilization. After culture of fertilized ova for 24 hr, only the TEM group exhibited a significant decrease in the number of fertilized ova which cleaved (85 vs 96% in the control). We conclude that the preimplantation loss caused by MeCl exposure is due to failure of fertilization and not to a genotoxic effect of MeCl. The methods used here permit a more accurate assessment of the reproductive toxicity of a chemical by discriminating between its cytotoxic and genotoxic effects.

The origin of the early embryonic loss that occurs during the first 4 days after mating in Californian doe-rabbits has been studied at 24 h or 60 h post coitum (p.c.). For comparison, 11 New Zealand doe-rabbits were slaughtered at the same times. The development stage of the embryo was determined after examination in toto at 24 h or by counting the morula nuclei at 60 h on histological sections. At 24 h p.c., 5.3% of the New Zealand eggs had not divided vs 37% of the Californian ones; this difference was highly significant. At 60 h p.c. frequency histograms of the number of morula nuclei showed that development was more variable in Californian does than in the New Zealand ones. However, the mean number of morula nuclei of each genotype was not significantly different. The higher proportion of Californian eggs (compared to New Zealand eggs) that were unfertilized or showed retarded segmentation is the main cause of the unexpectedly lower prolificacy of Californian rabbits.