39 FACTORS AFFECTING PREGNANCY RATE FOLLOWING TRANSFER OF SOMATIC CELL NUCLEAR TRANSFER EMBRYOS IN DOGS

2009 ◽  
Vol 21 (1) ◽  
pp. 119
Author(s):  
M. J. Kim ◽  
H. J. Oh ◽  
J. E. Park ◽  
J. T. Kang ◽  
S. G. Hong ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Serum Progesterone ◽  
Factors Affecting ◽  
Oocyte Donor ◽  
Surgical History ◽  
History Of ◽  
Analysis System

There have been attempts to find out factors influencing pregnancy rate after transfer of somatic cell nuclear transferred (SCNT) couplets in several species. The purpose of this study was to investigate the effects of parity, surgical history, and synchronization state between oocytes donor and recipient on the pregnancy rate following transfer of SCNT embryos in dogs. A total of 25 mixed-breed female dogs, aged 1 to 5 years old, weighing 20 to 35 kg were used in this study. In vivo-matured oocytes, obtained by flushing uterine tubes of donor dogs approximately 72 h after ovulation, were used for SCNT. Ovulation was determined by daily serum progesterone concentration. Reconstructed embryos (range = 7–36, average = 18.0 embryos) with normal morphology were surgically transferred into the ampullary portion of the uterine tube of recipient dogs. Pregnancy was determined at least 26 days after transfer by untrasonography. In experiment 1, recipient females were divided into 2 groups: nulliparous (7 bitches) and multiparous (17 bitches) groups. In experiment 2, recipient females were divided into 2 groups by surgical history: operated (10 bitches) and non-operated (14 bitches) groups. Operated group included those with a history of 1 laparotomy, either flushing of uterine tubes or SCNT embryo transfer. Non-operated group included those without history of any surgery. In experiment 3, recipient females were divided into 2 groups: synchronous (13 bitches) and asynchronous (7 bitches) groups. Synchronous was defined that the oocyte donor dog and the recipient dog ovulate at the same day. Asynchronous was defined that the oocyte donor dog ovulates 1 day earlier than the recipient. Data were analyzed using the Statistical Analysis System program (SAS Institute, version 9.1, Cary, NC, USA). In experiment 1, pregnancy rate was significantly higher in the multiparous group than the nulliparous group (23.5 v. 14.2%, P < 0.05). In experiment 2, surgical history did not influence the pregnancy rate between operated and non-operated groups (20.0 and 21.4%, respectively). In experiment 3, pregnancy rate was significantly higher in the asynchronous group than the synchronous group (42.9 v. 15.4%, P < 0.05). In conclusion, multiparous bitches improved the efficiency of SCNT embryo transfer. A higher pregnancy rate resulted when the oocyte donor dog’s ovulation time was 1 day earlier than that of the recipient dog. Other factors should be investigated for further improvement of the SCNT embryo transfer efficiency. This study was financially supported by the Korean MEST, through KOSEF (grant # M10625030005-08N250300510) and the BK21 program for Veterinary Science, and SNU foundation (Benefactor; RNL BIO).

scholarly journals Factors Affecting Pregnancy Rate Per Embryo Transfer of In Vivo Produced Embryos in Recipient Holstein Heifers

2020 ◽  
Vol 2 (2) ◽  
pp. 52-61
Author(s):  
Ahmed Marzouk ◽  
Tamer Genedy ◽  
Emad Abdelrazik ◽  
Ahmed Zaghloul ◽  
Hamed Elbaz
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Factors Affecting

100 FACTORS AFFECTING PREGNANCY RATES IN THE TRANSFER OF IN VITRO-PRODUCED JAPANESE BLACK CATTLE EMBRYOS

2017 ◽  
Vol 29 (1) ◽  
pp. 157
Author(s):  
T. Nishisouzu ◽  
A. Abe ◽  
S. Matoba ◽  
O. Dochi ◽  
K. Okamura
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Pregnancy Rates ◽  
Oestrous Cycle ◽  
Rapid Expansion ◽  
Japanese Black Cattle ◽  
Factors Affecting ◽  
Increased Activity

Despite the rapid expansion of in vitro embryo production (IVP) technology for genetic improvement in the cattle industry in the last decades, pregnancy rates by the transfer of IVP embryos are still lower than those derived from in vivo-produced embryos. The objective of this study was to analyse factors affecting pregnancy rates after the transfer of IVP Japanese Black cattle embryos under farm conditions. Holstein heifers (n = 4,475) and cows (n = 8,541) were selected as recipients. Most cows (80%) were managed in tie-stall barns and most heifers (80%) were managed in pens. Embryo transfers were performed for 9 years, from 2004 to 2012. The embryos were produced from oocytes derived from a local abattoir and semen from 14 proven bulls by the Livestock Improvement Association of Japan (Hamano and Kuwayama 1993 Theriogelogy 39, 703–712). The fresh IVP embryos (quality; IETS code 1) that reached the blastocyst stage after 7 to 8 days (insemination = Day 0) were transported by an airplane (2 h) and subsequently by a car (1.5 h). Embryos were non-surgically transferred to each recipient on Day 7 to 9 of their natural oestrous cycle on farms. Pregnancy was diagnosed on Day 40 to 60 after oestrus. Pregnancy results were statistically analysed using the GLM procedures of SAS. The following variables were included in the model: recipient parity (0, 1, 2, or 3), day (7, 8, or 9) of the oestrous cycle at the time of embryo transfer, oestrus behaviour (increased activity observed by farmers), presence of mucus at oestrus, presence of blood after oestrus, and year (1, 2, 3, 4, 5, 6, 7, 8, or 9) and season (April–June as spring, July–September as summer, October–December as fall, or January–March as winter) of embryo transfer. The Bonferroni correction was used to counteract the problem of multiple comparisons. Heifers had significantly higher pregnancy rates than cows (51.0% v. 37.9%, respectively; P < 0.01), and first parity cows had higher pregnancy rates than third parity cows (42.9% v. 35.7%, respectively; P < 0.01). Pregnancy rates were significantly higher in recipients that received an embryo transfer on Day 8 of their oestrous cycle, than on Day 7 (46.6% v. 42.4%, respectively; P < 0.01). Recipients without oestrus behaviour had higher pregnancy rates than those with oestrus behaviour (46.3% v. 43.4%, respectively; P < 0.01). The presence of mucus and/or blood after oestrus and the season of transfer were not found to significantly affect pregnancy rates. The results of this study indicated that performing IVP embryo transfers on Day 8 of a recipient’s oestrous cycle will improve the pregnancy rate, season does not have an effect on pregnancy rate, and the detection of oestrus by monitoring increased activity is not always reliable and instead should be determined by multiple symptoms on farm conditions.

Individualised luteal phase support in artificially prepared frozen embryo transfer cycles based on serum progesterone levels: a prospective cohort study

2021 ◽  
Author(s):  
Manuel Álvarez ◽  
Sofía Gaggiotti-Marre ◽  
Francisca Martínez ◽  
Lluc Coll ◽  
Sandra García ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Pregnancy Outcomes ◽  
Luteal Phase ◽  
Frozen Embryo Transfer ◽  
Ongoing Pregnancy ◽  
Serum Progesterone ◽  
Endometrial Preparation ◽  
Group 2 ◽  
Group 1

Abstract STUDY QUESTION Does an individualised luteal phase support (iLPS), according to serum progesterone (P4) level the day prior to euploid frozen embryo transfer (FET), improve pregnancy outcomes when started on the day previous to embryo transfer? SUMMARY ANSWER Patients with low serum P4 the day prior to euploid FET can benefit from the addition of daily subcutaneous P4 injections (Psc), when started the day prior to FET, and achieve similar reproductive outcomes compared to those with initial adequate P4 levels. WHAT IS KNOWN ALREADY The ratio between FET/IVF has spectacularly increased in the last years mainly thanks to the pursuit of an ovarian hyperstimulation syndrome free clinic and the development of preimplantation genetic testing (PGT). There is currently a big concern regarding the endometrial preparation for FET, especially in relation to serum P4 levels around the time of embryo transfer. Several studies have described impaired pregnancy outcomes in those patients with low P4 levels around the time of FET, considering 10 ng/ml as one of the most accepted reference values. To date, no prospective study has been designed to compare the reproductive outcomes between patients with adequate P4 the day previous to euploid FET and those with low, but restored P4 levels on the transfer day after iLPS through daily Psc started on the day previous to FET. STUDY DESIGN, SIZE, DURATION A prospective observational study was conducted at a university-affiliated fertility centre between November 2018 and January 2020 in patients undergoing PGT for aneuploidies (PGT-A) IVF cycles and a subsequent FET under hormone replacement treatment (HRT). A total of 574 cycles (453 patients) were analysed: 348 cycles (leading to 342 euploid FET) with adequate P4 on the day previous to FET, and 226 cycles (leading to 220 euploid FET) under iLPS after low P4 on the previous day to FET, but restored P4 levels on the transfer day. PARTICIPANTS/MATERIALS, SETTING, METHODS Overall we included 574 HRT FET cycles (453 patients). Standard HRT was used for endometrial preparation. P4 levels were measured the day previous to euploid FET. P4 &gt; 10.6 ng/ml was considered as adequate and euploid FET was performed on the following day (FET Group 1). P4 &lt; 10.6 ng/ml was considered as low, iLPS was added in the form of daily Psc injections, and a new P4 analysis was performed on the following day. FET was only performed on the same day when a restored P4 &gt; 10.6 ng/ml was achieved (98.2% of cases) (FET Group 2). MAIN RESULTS AND THE ROLE OF CHANCE Patient’s demographics and cycle parameters were comparable between both euploid FET groups (FET Group 1 and FET Group 2) in terms of age, weight, oestradiol and P4 levels and number of embryos transferred. No statistically significant differences were found in terms of clinical pregnancy rate (56.4% vs 59.1%: rate difference (RD) −2.7%, 95% CI [−11.4; 6.0]), ongoing pregnancy rate (49.4% vs 53.6%: RD −4.2%, 95% CI [−13.1; 4.7]) or live birth rate (49.1% vs 52.3%: RD −3.2%, 95% CI [−12; 5.7]). No significant differences were also found according to miscarriage rate (12.4% vs 9.2%: RD 3.2%, 95% CI [−4.3; 10.7]). LIMITATIONS, REASONS FOR CAUTION Only iLPS through daily Psc was evaluated. The time for Psc injection was not stated and no serum P4 determinations were performed once the pregnancy was achieved. WIDER IMPLICATIONS OF THE FINDINGS Our study provides information regarding an ‘opportunity window’ for improved ongoing pregnancy rates and miscarriage rates through a daily Psc injection in cases of inadequate P4 levels the day previous to FET (P4 &lt; 10.6 ng/ml) and restored values the day of FET (P4 &gt; 10.6 ng/ml). Only euploid FET under HRT were considered, avoiding one of the main reasons of miscarriage and implantation failure and overcoming confounding factors such as female age, embryo quality or ovarian stimulation protocols. STUDY FUNDING/COMPETING INTEREST(S) No external funding was received. B.C. reports personal fees from MSD, Merck Serono, Ferring Pharmaceuticals, IBSA and Gedeon Richter outside the submitted work. N.P. reports grants and personal fees from MSD, Merck Serono, Ferring Pharmaceuticals, Theramex and Besins International and personal fees from IBSA and Gedeon Richter outside the submitted work. The remaining authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER NCT03740568.

Factors affecting pregnancy rate following nonsurgical embryo transfer in buffalo (Bubalus bubalis) : A retrospective study

1999 ◽  
Vol 52 (1) ◽  
pp. 1-10 ◽  
Author(s):  
A.K. Misra ◽  
M. Mutha Rao ◽  
R. Kasiraj ◽  
N.S. Ranga Reddy ◽  
H.C. Pant
Keyword(s):  
Retrospective Study ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Bubalus Bubalis ◽  
Factors Affecting

Factors affecting pregnancy rate in embryo transfer recipients with reference to plasma progesterone

1989 ◽  
Vol 31 (1) ◽  
pp. 238 ◽  
Author(s):  
A.J. Payas ◽  
P.J. Broadbent ◽  
D.F. Dolman ◽  
W.B. Christie
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Plasma Progesterone ◽  
Factors Affecting

73 RE-CLONING BY SOMATIC CELL NUCLEAR TRANSFER FROM A CLONED KOREAN NATIVE GOAT

2007 ◽  
Vol 19 (1) ◽  
pp. 154
Author(s):  
J. K. Park ◽  
S. Y. Jung ◽  
S. H. Park ◽  
A. N. Ha ◽  
J. I. Jin ◽  
...  
Keyword(s):  
Somatic Cell ◽  
Pregnancy Rate ◽  
Somatic Cell Nuclear Transfer ◽  
Nuclear Transfer ◽  
Laser System ◽  
Serum Starvation ◽  
Factors Affecting ◽  
Estrous Synchronization ◽  
The Difference

Nuclear transfer (NT) is one of the most advanced technologies to increase animal efficiency in livestock production. Re-cloning can be utilized to investigate more effective methods for agricultural, biological, and medical research. However, few studies have been undertaken on re-cloning from cloned animals. The present study was conducted to examine some factors affecting in vitro development of re-cloned embryos and pregnancy by somatic cell nuclear transfer (SCNT). Ear fibroblast cells as karyoplast donors were isolated from a cloned Korean goat, Jinsoonny, 3 weeks after birth and cultured in serum-starvation condition (TCM-199 + 0.5% FBS) for cell confluence. Recipient oocytes were surgically collected by flushing the oviducts at 35 h after hCG injection from FSH-stimulated goats. The zonae pellucidae of the oocytes were partially drilled using a laser system and each somatic cell was individually transferred into an enucleated oocyte. The couplets were electrically fused and activated by ionomycin (5 min) and 6-DMAP (4 h). The reconstructed embryos were cultured in mSOF medium containing 0.8% BSA at 39�C in an atmosphere of 5% CO2, 5% O2, 90% N2 for 12 to 15 h. Re-cloned embryos (2- to 4-cell stages) were surgically transferred into the oviducts of the recipients. Estrous synchronization was induced by 10 days of treatment with a CIDR and a single injection of PGF2�. Pregnancy was diagnosed by progesterone assay and ultrasound on Days 21 and 63 of pregnancy. The fusion and cleavage rates of re-cloned oocytes were 87.5% (182/208) and 56.0% (102/182), respectively. A total of 175 re-cloned embryos were transferred into 28 recipients. Eleven (39.3%) and 4 recipients (14.3%) were confirmed pregnant on Days 21 and 60, respectively. In comparison of pregnany rate by estrous synchronization, a total of 66 and 109 re-cloned embryos were transferred into 11 recipients in natural estrus and 17 recipients in induced estrus, respectively. Five (45.4%) and 2 recipients (18.2%) in natural estrus were confirmed pregnant on Days 21 and 63, while 6 (35.3%) and 2 (11.8%) recipients in induced estrus were pregnant, respectively. There were no differences in pregnancy rate when the recipients were in estrus within 12 h of the donors (40 to 60%). However, the pregnancy rate was significantly decreased when the difference was greater than 24 h (0 to 35%; P &lt;&lt; 0.05). Re-cloning can be used for many purposes, and synchronization between donors and recipients may be an important factor for further success of nuclear transfer.

scholarly journals Studies on factors affecting superovulation and embryo transfer in Hungarian Merino ewes

2001 ◽  
Vol 49 (4) ◽  
pp. 431-441 ◽  
Author(s):  
S. Cseh ◽  
L. Solti
Keyword(s):  
Developmental Stage ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Ovarian Stimulation ◽  
Corpora Lutea ◽  
Treatment Protocols ◽  
Factors Affecting ◽  
Factors Influencing ◽  
Significant Difference ◽  
One Year

The objectives of this study were (a) to assess the ovulatory response and embryo production of Hungarian Merino ewes after superovulation, (b) to investigate the factors influencing the efficiency of embryo transfer (ET) in Hungarian Merino ewes, (c) to compare the results of two ovarian stimulation protocols (PMSG and PMSG+FSH treatment) in Hungarian Merino ewes, and (d) to study how superovulation, laparoscopic insemination and surgical embryo retrieval (ER) affect the subsequent reproduction of Hungarian Merino donor females after an ET programme. There was no significant difference between the ovarian stimulation protocols in the ratio of donor ewes responding to superovulation nor in the average number of corpora lutea. However, the number of transferable embryos recovered per donor ewe was higher in the PMSG+FSH group. The proportion of transferable embryos, unfertilised oocytes and degenerated embryos did not differ between the treatment protocols. The total pregnancy rate was 53.4% (179/335). Neither the developmental stage of the embryo nor the number of transferred embryos affect the implantation of embryos. However, the increased number of transferred embryos positively influenced the pregnancy rate. No difference was found in the pregnancy rate between synchronised and nonsynchronised groups of recipients. Thirty-six out of 45 donor ewes (80%) became pregnant within one year after the ET programme, indicating that ovarian stimulation and surgical ER did not affect adversely their reproduction.

204 RELATIONSHIP BETWEEN RESPIRATORY ACTIVITY AND THE PREGNANCY RATE OF BISECTED BOVINE EMBRYOS IN VIVO

2007 ◽  
Vol 19 (1) ◽  
pp. 219 ◽  
Author(s):  
S. Moriyasu ◽  
H. Hirayama ◽  
K. Sawai ◽  
S. Kageyama ◽  
S. Aoyagi ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Respiratory Activity ◽  
Pregnancy Rates ◽  
Bovine Embryos ◽  
Chi Square ◽  
Important Indicator ◽  
Consumption Rates

Oxygen consumption is an important indicator of the metabolic activity of living cells, which may provide valuable information for evaluating embryo quality. We have found that the bovine embryos with high oxygen consumption possess stronger potential for further development. However, the relationship between respiratory activity and the pregnancy rate of embryos is still unclear. In this study, we investigated the respiration rates of bisected bovine embryos and the pregnancy rates of demi-embryos after embryo transfer. Compact morula-stage embryos were bisected evenly by micro glass needle. One hundred bisected embryos were incubated for 24 h in embryo culture medium (IVD101; Research Institute for the Functional Peptides, Yamagata, Japan) at 39�C under 5% CO2, 5% O2, 90% N2. After the incubation, demi-embryos were classified into 2 groups: blastocoel-formed (BC) and blastocoel-not-formed (CM) embryos. Oxygen consumption rates of demi-embryos were measured by scanning electrochemical microscopy (SECM; Hokuto Denko Corporation, Tokyo, Japan). Within 3 h after the measurement, 80 demi-embryos were transferred into recipient cows (one demi-embryo/one recipient) at 7–8 days after estrus. Recipient cows were diagnosed for pregnancy by ultrasonography approximately 40 days after estrus. Statistical difference was analyzed by Tukey's post-hoc test and chi-square test. A total of 27 recipient cows became pregnant; the pregnancy rates for cows with CM and BC demi-embryos were 40.6% (13/32) and 29.2% (14/48), respectively. Mean oxygen consumption rates (� 10-14 mol s-1) in pregnant and non-pregnant cows were 0.47 and 0.39 for CM demi-embryos and 0.63 and 0.52 for BC demi-embryos, respectively. Retrospective analysis showed that the respiratory activity of demi-embryos in the pregnant group was higher than those in the non-pregnant group. In particular, the pregnancy rates for demi-embryos with respiratory activity higher than 0.35 in CM and 0.40 in BC groups were 52.0% (13/25) and 35.9% (14/39), respectively. On the other hand, cows with demi-embryos having an oxygen consumption rate under 0.35 in CM (n = 7) and 0.40 in BC (n = 9) groups did not become pregnant. These results demonstrated that bovine demi-embryos with higher respiratory activity showed a high pregnancy rate after embryo transfer. It is generally known that the pregnancy rate after the transfer of bisected embryos is lower than that of whole embryos. The measurement of oxygen consumption by SECM procedures is a useful tool to assess the quality of pre-implantation embryos and may contribute to the improvement of the success rate for bisected embryo transfer.

37 EFFECT OF EMBRYO STAGE ON PREGNANCY RATE FOLLOWING DIRECT TRANSFER OF BOVINE EMBRYOS FROZEN IN ETHYLENE GLYCOL

2012 ◽  
Vol 24 (1) ◽  
pp. 131 ◽  
Author(s):  
J. F. Hasler
Keyword(s):  
Ethylene Glycol ◽  
Pregnancy Rate ◽  
Embryo Transfer ◽  
The United States ◽  
Pregnancy Rates ◽  
Bovine Embryos ◽  
Embryo Freezing ◽  
Percentage Points ◽  
Embryo Stage

Annually, more than 400 000 in vivo-recovered bovine embryos are officially reported by members of the Canadian and American Embryo Transfer Associations. Between 65 and 70% of these embryos are cryopreserved and more than 95% are frozen in ethylene glycol (EG). Statistics on factors affecting embryo freezing are difficult to obtain because many cattle breeders/farmers no longer report pregnancy rates back to embryo transfer (ET) practitioners. Concerns are often expressed as to the optimal stage at which to freeze bovine in vivo-derived embryos. This is a retrospective analysis of results from 5 commercial ET programs (1 in the United States, 3 in Canada and 1 in the Netherlands) for which pregnancy data relative to embryo stage at freezing were made available. Embryos representing 4 stages of development, as defined by the IETS (4 = late morula, 5 = early blastocyst, 6 = mid blastocyst and 7 = expanded blastocyst) are included in the data. The number of embryos thawed and transferred ranged from 3954 to 24 827 for the 5 programs, with a total of 72 828. Embryos were frozen in either 1.5 M EG or 1.5 M EG + 0.1 M sucrose and exposure time to cryoprotectant before cooling ranged from 4 to 40 min. Pregnancy rates are shown in Table 1. Although the pregnancy rate for stage 6 embryos was only 2.6 and 3.2 percentage points lower than stages 4 and 5, respectively, these differences were highly significant and pregnancy rates for stage 6 embryos were lower than those for stages 4 and 5 in 4 of the 5 ET programs. The small decreased survival of stage 6 embryos is probably only moderately important in a commercial context. However, the pregnancy rate of stage 7 embryos was lower than all other stages for the combined dataset as well as in all 5 ET programs, with the difference between stages 5 and 7 ranging from 6.5 to 16.4 percentage points. Clearly, stage 7 embryos survive freezing at a significantly lower rate than stages 4, 5 and 6 and neither time of exposure to EG nor inclusion of sucrose in the freezing medium provided an obvious improvement. Although bovine ET practitioners routinely attempt to collect embryos on day 7 post-oestrus, recovery of stage 7 embryos cannot always be avoided. Further investigation into factors contributing to the decreased survival of stage 7 embryos is warranted. Table 1.Effect of embryo stage on pregnancy rate of bovine embryos frozen in EG

363 FACTORS INFLUENCING PREGNANCY RATES FOLLOWING TRANSFER OF BOVINE IN VIVO EMBRYOS BIOPSIED FOR SEX DETERMINATION

2007 ◽  
Vol 19 (1) ◽  
pp. 297
Author(s):  
S. Li ◽  
W. Yu ◽  
J. Fu ◽  
Y. Bai ◽  
F. Jin ◽  
...  
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Pregnancy Rates ◽  
Chi Square ◽  
Embryo Survival ◽  
Chi Square Test ◽  
First Time ◽  
Fresh Embryos

Data collected from commercial embryo transfer programs in 63 farms in China during June 2002 to December 2005 was analyzed to examine the effects of various factors (biopsy, freezing, sample size, embryo development and quality, in vitro culture, and recipient quality) on pregnancy rates of in vivo-biopsied embryos. Embryos were flushed from superovulated dairy cattle and subjected to a biopsy for sexing determination using protocols and sexing kits supplied by AB Technology Ltd. Fresh embryos were implanted on the same day or frozen with AG freeze medium (AB Technology Ltd., Pullman, WA, USA) for later transfer. Recipients were synchronized with CIDA + PG protocols. Embryos were cultured in 6-well dishes containing 1.3 mL of holding medium (AB Technology Ltd.) in each well at room temperature (20–25�C) for examination of embryo survival in vitro. The chi-square test was used in statistic analysis. The implantation of fresh embryos after biopsy did not affect pregnancy rates (49.6%, 257/518) compared to that of non-biopsied fresh and frozen–thawed embryo groups (52.9%, 47/140 and 46.6%, 177/380, respectively). However, for biopsied embryos subjected to frozen and thawed procedures before implantation, particularly for those subjected to the removal of a larger biopsy, a reduced pregnancy rate was observed (41.8%, 297/710; P &lt; 0.01). Pregnancy rates among biopsied embryos at 3 different development stages (morula-early blastocyst, blastocyst, and expanded blastocyst) were not different. Similar results were found between embryo groups of grade 1 and 2. A significant decrease in pregnancy rate (0/10) was observed with embryos held in vitro for a longer period of time (&gt;5 h), suggesting detrimental effects of in vitro conditions on embryo survival. The highest pregnancy rate (68.0%) was observed in recipients synchronized for the first time before being implanted with biopsied embryos. Significant decreases in such rates were found in recipients synchronized for the second or third times or those with an abortion history at the first or second synchronization-implantation treatment (P &lt; 0.01). Better pregnancy rates (45.6%, 41/90; 46.1%, 76/165; and 45.5%, 5/11) were obtained for recipients implanted with biopsied embryos at Days 7.5, 8.0, and 8.5 post-heat detection, respectively, compared to 16% at Day 7 (3/18, P &lt; 0.05). It is concluded that mechanical treatment (cutting) does not reduce the survival of biopsied embryos; however, cryopreservation reduces their ability to survive in vivo. The analyses also suggest that holding embryos in vitro should not be longer than 5 h unless more favorable in vitro conditions can be provided. To achieve better results of implantation of biopsied embryos, embryo transfer should be performed during 7.5–8.5 days post-estrus, and the healthy recipients synchronized for the first time should be used.

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