scholarly journals 120PREGNANCY RATES RESULTING FROM TRANSFER OF FRESH AND FROZEN HOLSTEIN AND JERSEY EMBRYOS

2004 ◽  
Vol 16 (2) ◽  
pp. 182 ◽  
Author(s):  
R. Steel ◽  
J.F. Hasler
Keyword(s):  
Ethylene Glycol ◽  
Dairy Farms ◽  
Pregnancy Rates ◽  
Embryo Survival ◽  
Embryo Freezing ◽  
Retrospective Comparison ◽  
Frozen Embryos ◽  
Embryo Stage ◽  
In Pregnancy ◽  
Fresh Embryos

Although it has not been documented in published studies, embryo transfer (ET) practitioners have suggested that embryos from Jersey (JE) cattle do not survive freezing as well as embryos from other dairy breeds such as Holsteins (HO). The present study represents a retrospective analysis of pregnancy rates achieved following transfer of fresh and frozen embryos from Jersey and Holstein donors. In addition, a retrospective comparison was made of two different embryo-freezing protocols for each breed of cattle. Embryos were collected nonsurgically 7 to 7.5 days post-estrus from superovulated donors on 57 Holstein and 27 Jersey dairy farms over a 15-year period. Fresh and frozen-thawed embryos were transferred nonsurgically into cows and heifers following either natural or prostaglandin-induced estrus. Embryos were frozen either in 10% glycerol (Gly) or 1.5M ethylene glycol (EG) in 0.25mL straws. Following equilibration, straws were seeded at −6 to −7°C and temperature was maintained for 10 min and then decreased at 0.6°Cper min. Straws were plunged into liquid nitrogen at −32 to −35°C. At thawing, straws were held in the air for 7s and then submerged in 29°C water for 15s. Embryos frozen in EG were transferred immediately following thawing. Embryos frozen in Gly were rehydrated in a standard 3-step Gly-sucrose system prior to being transferred. Pregnancy diagnosis was performed at Days 40 to 90 of gestation. As seen in the Table 1, pregnancy rates were similar for fresh embryos from both HO and JE cattle. Also, there were no differences in pregnancy rates between recipients that received embryos frozen in Gly or EG within donors of either breed. However, JE embryos frozen in either Gly or EG resulted in lower pregnancy rates than did HO embryos frozen in Gly or EG. Embryo stage at freezing was tracked for EG but not Gly embryos. There were no differences in pregnancy rates among morulae, early blastocysts or mid-blastocysts for either HO or JE embryos frozen in EG. The differences in embryo survival may be due to different lipid composition of embryos of the two breeds. Perhaps a more efficacious freezing protocol can be developed for cryopreservation of JE embryos. In conclusion, pregnancy rates with cryopreserved HO embryos were higher than with JE embryos. Table 1

191 INFLUENCE OF THE DIFFERENT TIME COMPONENTS BETWEEN FLUSHING AND TRANSFER ON PREGNANCY RATES OF FROZEN CATTLE EMBRYOS

2006 ◽  
Vol 18 (2) ◽  
pp. 203
Author(s):  
C. Ponsart ◽  
H. Quinton ◽  
A. Rohou ◽  
J. Kelhembo ◽  
G. Bourgoin ◽  
...  
Keyword(s):  
Pregnancy Rates ◽  
Chi Square ◽  
Frozen Embryos ◽  
Multivariate Logistic Model ◽  
Parity Number ◽  
Embryo Stage ◽  
Chi Square Analysis ◽  
Fresh Embryos ◽  
Donor Cows

Previous studies have shown that the time between flushing and freezing of bovine embryos can influence pregnancy rates (PRs) following embryo transfer (ET). The aim of this study was to determine which time components can influence ET results. Time components between flushing of a superovulated donor and freezing of the collected embryos were investigated under field conditions. Embryos were frozen in 1.5 M ethylene glycol (EG) for direct transfer. During January 2003, ET technicians (EmbryoTop, Rennes cedex, France) recorded systematically times corresponding to each step comprising the time spent in vitro (TIV) from 153 recovery sessions (RS) with freezing: end of flushing, beginning and end of search of embryos, start of equilibration in EG, beginning and end of straw loading, introduction to −7°C in the freezer, and seeding. Numbers of donor cows and ET technicians doing the freezing (n = 5) were noted for each RS. Embryo (stage, quality) and recipient (breed, parity) characteristics were also noted. A total of 548 frozen embryos were transferred and PRs were assessed. Variability of time components was investigated (Bourgoin et al. 2004 Reprod. Fertil. Dev. 16, 207). The influence of time components and other variation factors was tested on PRs (t-tests and chi-square analysis). The TIV averaged 210 ± 80 min and did not influence PR (≤4 h = 51.9% (n = 393) vs. >4 h = 55.5% (n = 155); P > 0.05), as well as duration of flushing (32 ± 8 min), interval between end of flushing and search (31 ± 27 min), duration of search (45 ± 25 min) and interval between end of search and beginning of freezing (101 ± 63 min). Only significant factors were kept for further analysis. The effects of recipient parity, number of donor cows per RS, and interval between introduction of straw to −7°C, and seeding were tested in a multivariate logistic model. PR varied strongly with parity of recipient (+25% in heifers vs. cows; P = 0.001). PRs were higher when the interval between straw introduction in the freezer and seeding lasted at least 5 min (2–4 min = 48.0% (n = 254) vs. 5–8 min = 57.1% (n = 294); P = 0.009). Time and operator effects were confounded. Overall PR results for the two technicians who used mostly 2–4 min intervals averaged 47% (operator values = 35.6, 48.9, and 54.5) whereas PRs were 54.9 and 60.5% for those waiting 5 min or more before inducing seeding (n = 2). PRs were higher when at least two donor cows were collected per RS (1 donor cow = 49% (n = 259) vs. ≥2 donor cows = 56.4% (n = 289); P = 0.003). This was not in agreement with previous observations in fresh embryos (Bourgoin et al. 2004). However, the number of donor cows strongly influenced the number of viable embryos per RS (1 donor cow = 11 ± 5 vs. ≥2 donor cows = 18 ± 8.5; P < 0.05) and could permit the choice of more embryos to be frozen. These results show that good PR may be achieved with a delay of several hours between flushing and freezing, when heifers are used as recipients. Moreover, confirmed from higher numbers of operators, these data show that it is better to wait at least 5 min to achieve equilibration of the embryo before seeding.

scholarly journals 97 ASSESSMENT OF VIABILITY OF IN VITRO PRODUCED BOVINE EMBRYOS FOLLOWING VITRIFICATION BY CVM OR SLOW FREEZING WITH ETHYLENE GLYCOL AND TRIPLE TRANSFER

2005 ◽  
Vol 17 (2) ◽  
pp. 199 ◽  
Author(s):  
B. Peachey ◽  
K. Hartwich ◽  
K. Cockrem ◽  
A. Marsh ◽  
A. Pugh ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Survival Rates ◽  
Slow Freezing ◽  
High Survival ◽  
Bovine Embryos ◽  
Embryo Survival ◽  
Frozen Embryos ◽  
Morula Stage ◽  
Fresh Embryos

Vitrification has become the method of choice for the preservation of in vitro derived embryos of a number of species, and several methods of vitrification have been developed. One such method, the cryoLogic vitrification method (CVM) yields high survival rates of warmed embryos (Lindemans W et al. 2004 Reprod. Fertil. Dev. 16, 174 abst). In this study, the post-warm viability of bovine IVP embryos following either vitrification using CVM or slow freezing using ethylene glycol (EG) was compared. In addition, the survival of embryos following triple transfer to synchronized recipients was measured and the embryo (“e”) and recipient (“r”) contributions to embryo survival was determined using the “er” model for embryo survival (McMillan WH et al. 1998 Theriogenology 50, 1053–1070). Bovine IVP methods were those of van Wagtendonk et al. 2004 Reprod. Fertil. Dev. 16, 214 (abst). On day 7 of culture (Day 0 = IVF), Grade 1 and 2 embryos that had reached at least the late morula stage were selected for vitrification (20% DMSO, 20% ethylene glycol) or freezing in 1.5 M ethylene glycol + 0.1 M sucrose (0.5°C/min to −35°C). Following storage in LN2 for at least 24 h the embryos were thawed, the cryoprotectant removed, and the embryos cultured for 72 h in mSOF medium under 5% CO2, 7% O2, 88% N2. The number of hatching embryos was recorded at 24-h intervals. In addition, blastocyst and expanded blastocyst embryos were thawed and immediately transferred nonsurgically to recipients (three embryos of the same grade to each recipient) on Day 7 of a synchronized cycle (Day 0 = heat). The recipients were ultrasound-scanned for the presence of, and number of, fetuses on Days 35 and 62, respectively. The invitro assessment of 148 CVM and 230 EG frozen embryos indicated that more vitrified than EG embryos hatched by 72 h (73% vs. 62%; CVM vs. EG, χ2 = 4.5, P < 0.05). Overall, more Grade 1 embryos hatched than Grade 2 (74% vs. 60%, χ2 = 7.2, P < 0.01). CVM embryos (105) were triple-transferred to 35 recipients, and EG embryos (30) were triple-transferred to 10 recipients. Recipient pregnancy rates at Day 62 were 80% and 70%, respectively. Overall embryo survival was 38.5% (41% for CVM and 30% for EG). The overall calculated “e” and “r” values were 0.39 and 1.0 (“e”: 0.42 and 1.0, and “r”: 0.31 and 1.0, respectively, CVM and EG groups). Survival rates of CVM embryos to Day 62 (41%) were slightly lower than that previously obtained for fresh embryos produced using an identical IVP procedure (44% – van Wagtendonk AM 2004).

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

97 BOER GOAT OFFSPRING BORN FOLLOWING TRANSFER OF CRYOPRESERVED EMBRYOS

2010 ◽  
Vol 22 (1) ◽  
pp. 207
Author(s):  
K. C. Lehloenya ◽  
J. P. C. Greyling
Keyword(s):  
Survival Rate ◽  
Pregnancy Rate ◽  
Genetic Material ◽  
Embryo Survival ◽  
Boer Goat ◽  
Frozen Embryos ◽  
Group 2 ◽  
The University ◽  
Fresh Embryos ◽  
Cryopreserved Embryos

Cryopreservation of embryos is an important technique in the whole MOET program, which could help improve the transportation of genetic material across South Africa and globally. This trial evaluated the survival rate of goat embryos following transfer with cryopreserved Boer goat embryos. Twenty-seven multiparous Boer goat recipients were synchronized with CIDR for 16 days and injected with 300 IU of eCG at CIDR withdrawal. The recipients were allocated into 3 groups (n = 9). Group 1 received fresh embryos; Group 2 received slow frozen embryos; and Group 3 received vitrified embryos. Expanded blastocysts used were surgically collected from donors superovulated with pFSH on 7 following AI. Two blastocysts were transferred laparoscopically to the uterine horn ipsilateral to functional CL. A pregnancy rate of 85.7% (6) was obtained following the transfer of fresh embryos and tended to be better than in the does receiving slow frozen and vitrified embryos, (n = 4; 50.0% and n = 3; 37.5% does pregnant, respectively) with no significant differences. The kidding rate of the recipient does declined to 57.0% (4) and 25.0% (2) for fresh and slow frozen groups, respectively. The embryo survival rate of 35.7% (n = 5) for fresh, 25.0% (n = 4) for conventional slow freezing and 31.3% (n = 5) for vitrification was obtained and was not affected by the number of CL present on the respective ovaries at the time of embryo transfer. Although the pregnancy rate following the transfer of fresh embryos was satisfactory, the embryo survival rate following the transfer of fresh or cryopreserved embryos tended to be lower. The authors acknowledge the University of the Free State for financial and facility support and National Research Foundation (Thuthuka) for financial support for conducting this trial.

Exogenous progesterone and embryo survival in Booroola-cross ewes

1991 ◽  
Vol 3 (1) ◽  
pp. 71 ◽  
Author(s):  
DO Kleemann ◽  
SK Walker ◽  
RJ Grimson ◽  
DH Smith ◽  
TI Grosser ◽  
...  
Keyword(s):  
Drug Release ◽  
Pregnancy Rates ◽  
Embryo Survival ◽  
Treatment Groups ◽  
F Gene ◽  
Exogenous Progesterone ◽  
In Pregnancy ◽  
Australian Merino

To investigate if exogenous progesterone improves embryo survival, 209 multiparous Booroola Merino x South Australian Merino ewes, heterozygous for the F gene (F+) were allocated to seven treatment groups and inseminated at a synchronized oestrus. Six groups received progesterone from controlled internal drug release G dispensers on the following days after ovulation: 4-7, 4-11, 4-14, 7-11, 7-14 and 11-14. Concentration of peripheral progesterone increased (P less than 0.05) in most supplemented groups, but there were no significant differences in pregnancy rates between treatments. However, the number of fetuses per pregnancy was increased for progesterone treatments starting on Day 4 (Days 4-7, 4-11 and 4-14 combined v. control; P less than 0.05) and for all supplemented treatments compared with the control (P less than 0.05).

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.

scholarly journals Effects of parity and season on pregnancy rates after the transfer of embryos to repeat-breeder Japanese Black beef cattle

2016 ◽  
Vol 59 (1) ◽  
pp. 45-49 ◽  
Author(s):  
T. Ono ◽  
T. Isobe ◽  
Y. Morita ◽  
L. T. K. Do ◽  
F. Tanihara ◽  
...  
Keyword(s):  
Heat Stress ◽  
Beef Cattle ◽  
Embryo Transfer ◽  
Reproductive Performance ◽  
Pregnancy Rates ◽  
Frozen Embryos ◽  
Repeat Breeder ◽  
Fresh Embryos

Abstract. Repeat-breeder (RB) cows are a major source of economic waste due to their decreased fertility. Embryo transfer (ET) is an alternative tool to improve the fertility of RB cows. The aims of the present study were to evaluate the effects of recipient parity and the season on pregnancy rates following ET in RB Japanese Black beef cattle. Embryos were transferred nonsurgically to recipients, consisting of 155 heifers (< 2 years old) and 172 cows (< 8 years old), which were defined as RB cattle. Of the recipients that were presented for ET, 57 recipients received a fresh embryo and 270 recipients received a frozen embryo. There were no differences in the pregnancy rates between cattle that received fresh embryos or frozen embryos. The rates of recipients with pregnancy, abortion, stillbirth, and normal calving were similar between heifers and cows. In cows, the pregnancy rates were lower (P < 0.05) in summer (June to August) than in spring (March to May) and winter (December to February). In heifers, however, there were no differences in the pregnancy rates among the seasons. Our findings indicate that in RB Japanese Black beef cattle, the parity of the recipients does not have an effect on the pregnancy rates following the transfer of fresh and frozen embryos. However, heat stress may affect reproductive performance in RB Japanese Black cows.

149 IN VITRO BOVINE EMBRYOS FROZEN BY DIRECT TRANSFER METHOD WITH ETHYLENE GLYCOL

2015 ◽  
Vol 27 (1) ◽  
pp. 166
Author(s):  
S. H. Kizil ◽  
M. Satilmis ◽  
N. Akyol ◽  
T. Karasahin
Keyword(s):  
Ethylene Glycol ◽  
Survival Rates ◽  
Hatching Rate ◽  
Direct Transfer ◽  
Embryo Freezing ◽  
Frozen Embryos ◽  
Transfer Method ◽  
Phosphate Buffered Saline ◽  
In Vitro Survival

The objective of this study was to search for capability of freezing by ethylene glycol direct transfer method of in vitro-produced cattle embryos. Fifty-six in vitro-produced good-quality cow embryos were frozen by direct transfer method with ethylene glycol in this study. Cattle ovaries were collected from a slaughterhouse and oocytes were aspirated from follicles with 2 to 8 mm diameters. Then oocytes were let for maturation of 20 to 22 h in 100-μL microdroplets of TCM-199 with 0.1 mM β-mercaptoethanol and 20% FCS. After 5 to 6 h of fertilization in Bracket Oliphant (BO), they were cultured for 7 days in 100 µL of CR1aa medium with 5% FCS under 5% CO2, 98% relative humidity, and 38.5°C in a CO2 incubator. Embryos were equilibrated for 15 min in room temperature in 1.8 M ethylene glycol + 0.1 M sucrose in Dulbecco's phosphate buffered saline (D-PBS) supplemented with 20% FCS. Embryos were then loaded individually into a 0.25-mL straw and placed directly into a cooling chamber of a programmable freezer with methyl alcohol precooled to –7°C. After 2 min, the straw was seeded and maintained at –7°C for 8 min more. Then it was cooled to –30°C at 0.3°C min–1 before plunging into liquid nitrogen. The frozen embryos were thawed by allowing the straw to stand in air for 5 to 6 s and then immersing them in a 30°C water bath for 10 s. After thawing, embryos were transferred into TCM-199 + 0.1 mM β-mercaptoethanol + 20% FCS medium to check in vitro survival rates at 48 h post-thawing. The re-expansion and hatching rate of blastocysts was 64.28% (36 blastocysts). This result indicated that ethylene glycol can be used effectively for cow embryo freezing as a suitable cryoprotectant for direct transfer method.

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

2018 ◽  
Vol 30 (1) ◽  
pp. 181
Author(s):  
S. Khunmanee ◽  
J. Suwimonteerabutr ◽  
M. Techakumphu ◽  
T. Swangchan-Uthai
Keyword(s):  
Pregnancy Rate ◽  
Embryo Transfer ◽  
Blastocyst Stage ◽  
Pregnancy Rates ◽  
Slow Freezing ◽  
Small Scale ◽  
Tropical Conditions ◽  
Frozen Embryos ◽  
Embryo Stage ◽  
Cryopreservation Method

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

scholarly journals Freezing goat embryos at different developmental stages and quality using ethylene glycol and a slow cooling rate

2018 ◽  
Vol 70 (5) ◽  
pp. 1489-1496 ◽  
Author(s):  
J.F. Fonseca ◽  
R.I.T.P. Batista ◽  
J.M.G. Souza-Fabjan ◽  
M.E.F. Oliveira ◽  
F.Z. Brandão ◽  
...  
Keyword(s):  
Ethylene Glycol ◽  
Cooling Rate ◽  
Liquid Nitrogen ◽  
Developmental Stages ◽  
Slow Cooling ◽  
Air Bubble ◽  
Frozen Embryos ◽  
Glycol Solution ◽  
Fresh Embryos ◽  
Fresh Transfer

ABSTRACT The efficiency of an alternative freezing protocol for goat embryos of different morphology and quality was tested. Fifty-eight embryos on Day 6-7 stage were transferred as fresh or after freeze-thawing (n=29/group). For freezing, embryos were placed into 1.5M ethylene-glycol solution for 10min. During this time, they were loaded in the central part of 0.25mL straw, separated by air bubble from columns containing PBS/BSA 0.4% plus 20% BFS. Straws were then frozen using a freezing machine from 20ºC to -6ºC at a cooling rate of 3ºC/min, stabilization for 15min (seeding after 5min), from -6 C to -32ºC at 0.6 C/min,and plunged into liquid nitrogen. Frozen embryos were thawed for 30s at 37ºC in a water bath. Embryos subjected to fresh transfer were maintained in holding medium (37ºC). Fresh and frozen-thawed embryos were transferred at day 7 post-estrus to 30 recipients. Kidding and kid born rates were similar (P> 0.05), respectively, for recipients receiving fresh (66.7% or 10/15; 55.2% or 16/29) or frozen-thawed (60% or 9/15; 51.7% or 15/29) embryos. The cryopreservation of goat embryos using slow-freezing protocol and 1.5MEG resulted in similar efficiency rates of fresh embryos.

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