scholarly journals Selection of Immature Cat Oocytes with Brilliant Cresyl Blue Stain Improves In Vitro Embryo Production during Non-Breeding Season

Animals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 1496
Author(s):  
Anna Rita Piras ◽  
Federica Ariu ◽  
Maria-Teresa Zedda ◽  
Maria-Teresa Paramio ◽  
Luisa Bogliolo
Keyword(s):  
Breeding Season ◽  
Domestic Cat ◽  
Hatching Rate ◽  
Domestic Cats ◽  
Embryo Production ◽  
Brilliant Cresyl Blue ◽  
Cresyl Blue ◽  
In Vitro Embryo Production ◽  
Blastocyst Rate

In domestic cats, the maturation, fertilization, and development potential in vitro decreases during the non-breeding season. This study aims at evaluating the efficacy of Brilliant Cresyl Blue (BCB) staining in selecting developmentally competent oocytes to be used in in vitro embryo production (IVEP) programs in order to overcome the season variability in blastocyst yield. Cumulus-oocytes complexes (COCs) collected from antral follicles of domestic cat ovaries during the anestrus phase (July to November) were selected by BCB staining and classified as BCB+ (colored cytoplasm) and BCB− (colorless cytoplasm). COCs not exposed to BCB staining were used as control. Before and after in vitro maturation mitochondrial activity and reactive oxygen species (ROS) were measured. Following in vitro fertilization, blastocyst rate, hatching rate, and blastocyst cell numbers were recorded. The results show that BCB staining did not alter the mitochondrial function and ROS production in cat oocytes. BCB+ oocytes presented a higher (p < 0.05) blastocyst rate, hatching rate, and blastocyst cell number than BCB− and control oocytes. In conclusion, BCB staining does not affect the bioenergetic/oxidative status of the oocyte while being a useful tool for selecting good quality oocytes to increase IVEP in domestic cats during non-breeding season.

scholarly journals Effect of deslorelin acetate treatment in oocyte recovery and in vitro embryo production in domestic cats

2016 ◽  
Vol 19 (10) ◽  
pp. 1091-1095
Author(s):  
Camila Louise Ackermann ◽  
Eduardo Trevisol ◽  
Leticia Ferrari Crocomo ◽  
Tatiana da Silva Rascado ◽  
Rodrigo Volpato ◽  
...  
Keyword(s):  
Treated Group ◽  
Control Group ◽  
Domestic Cats ◽  
Cleavage Rate ◽  
Embryo Production ◽  
Oocyte Recovery ◽  
Significant Difference ◽  
In Vitro Embryo Production ◽  
Blastocyst Rate

Objectives The present study investigated the effect of contraceptive treatment with deslorelin acetate on in vitro embryo production and oocyte recovery in domestic queens. Methods Twenty-one mature domestic cats were used. Eleven queens (treated group) and one tom were kept in an experimental cattery, and 10 queens were privately owned (control group). When in interestrus or diestrus (day 0) a deslorelin acetate implant (Suprelorin, 4.7 mg/animal) was inserted into the subcutaneous tissue of the interscapular region in all queens in the treated group. After 6 months of treatment, all animals were ovariohysterectomized, and the ovaries were used for in vitro embryo production. Percentage of cleavage was determined 18 h after oocyte insemination and blastocyst formation was assessed on the eighth day of culture. The rate of cumulus-oocyte complexes (COCs) recovery was analyzed by an unpaired t-test. The cleavage and blastocyst rates were expressed as percentages and analyzed by Fisher’s exact test. All analyses were performed using GraphPad Prism v5.0, with P <0.05 set as the level of significance. Results In the treated group, we recovered 8.3 ± 1.15 grade I COCs per queen; the cleavage rate was 60% and the blastocyst rate was 36%. In the control group, we recovered 18.4 ± 3.21 grade I COCs per queen; the cleavage rate was 55.97% and the blastocyst rate was 34%. Forty percent of treated females did not produce any blastocysts. In the treated group, we observed a significant decrease in COC recovery. Although there was no significant difference in cleavage and blastocyst rates between groups, 40% of treated females did not produce any blastocysts. Conclusions Recovery of grade I COCs is negatively affected by deslorelin treatment in domestic cats. Regarding embryo production, new studies are still necessary to evaluate the success of this technique owing to the individual effect caused by deslorelin acetate.

205 GLUCOSE-6-PHOSPHATE DEHYDROGENAZE ACTIVITY IN OVINE OOCYTES IS ASSOCIATED WITH PRE-IMPLANTATION EMBRYONIC DEVELOPMENT IN VITRO

2011 ◽  
Vol 23 (1) ◽  
pp. 201 ◽  
Author(s):  
F. Asghari ◽  
M. Shahidi ◽  
Y. Chashnidel ◽  
H. Deldar ◽  
Z. Ansari-Pirsaraei ◽  
...  
Keyword(s):  
Oocyte Quality ◽  
G6pd Activity ◽  
Blue Staining ◽  
Control Group ◽  
Embryo Production ◽  
Brilliant Cresyl Blue ◽  
Cresyl Blue ◽  
In Vitro Embryo Production ◽  
Humidified Air

A large proportion of ovine oocytes fail to develop into viable embryos following maturation, fertilization, and culture in vitro. Accurate, fast, and noninvasive predictors of ovine oocyte quality are therefore in urgent need for oocyte selection before in vitro maturation (IVM). Recent studies have shown that oocyte competence can be predicted through the presence of the glucose-6-phosphate dehydrogenase (G6PD) enzyme, as indicated by brilliant cresyl blue (BCB), a dye that can be degraded by G6PD. Thus, oocytes that have completed their growth phase show decreased G6PD activity and exhibit cytoplasm with a blue colouration (BCB+), whereas growing oocytes are expected to have a high level of G6PD, which results in colourless cytoplasm (BCB–). The brilliant cresyl blue staining test, as a noninvasive intrinsic criterion, has been successfully used to identify the more competent oocytes in various species. Therefore, this study aimed to investigate whether BCB staining, as an indicator of G6PD activity, can be used to select developmentally competent ovine oocytes before IVM and thereby increase the efficiency of in vitro embryo production. Ovine ovaries were obtained from a local slaughterhouse and transported to the laboratory, where cumulus–oocyte complexes (COC) were recovered by slicing the ovaries. Only oocytes with one or more complete layers of unexpanded cumulus cells and a homogeneous cytoplasm were used. The COC were exposed to 26 mM BCB diluted in modified Dulbecco’s PBS for 90 min at 39°C in humidified air. After BCB exposure, the COC were examined under a stereomicroscope and divided into 2 groups: BCB+ (blue cytoplasm, low G6PD activity) and BCB– (colourless cytoplasm, high G6PD activity). Cumulus–oocyte complexes in the control group were incubated for IVM directly after selection, without exposure to BCB dye. After IVM, oocytes were subjected to IVF followed by embryo culture for 7 days (5% CO2, 39°C, humidified air). Results were analysed by a chi-square test, and P < 0.05 was considered statistically significant. The proportion of oocytes that cleaved by Day 2 after insemination was significantly (P < 0.05) higher for the control and BCB+ groups [67.3% (68/101) and 71.7% (81/113), respectively] than for the BCB– group [50.5% (46/91)]. Significant differences among groups were also observed on Day 7 after fertilization, when the embryos reached the blastocyst stage of development. The BCB+ group yielded a significantly (P < 0.05) higher proportion of blastocysts [34.5% (39/113)] than both the control [20.8% (21/101)] and BCB– [4.3% (4/93)] groups. In addition, the blastocyst rate of development in the control group was significantly (P < 0.05) higher than that for the BCB– group. In conclusion, results of this study show that selection of ovine oocytes based on G6PD activity through the BCB test can be used as an efficient predictor of in vitro embryonic developmental competence. This positive predictive parameter of oocyte quality may also be useful in increasing the efficiency of blastocyst production during in vitro embryo production procedures in the ovine.

PSX-A-23 Late-Breaking: Supplementation of Nerve Growth Factor (β-NGF) in the maturation medium and efficiency of in vitro embryo production in cattle

2021 ◽  
Vol 99 (Supplement_3) ◽  
pp. 365-365
Author(s):  
Lucas Gonçalves ◽  
Muller C Martins ◽  
Natalia Arle ◽  
Rafaela T Torres ◽  
Luisa Migilo ◽  
...  
Keyword(s):  
Nerve Growth Factor ◽  
Growth Factor ◽  
Oocyte Maturation ◽  
Cleavage Rate ◽  
Embryo Production ◽  
Nerve Growth ◽  
Maturation Medium ◽  
In Vitro Embryo Production ◽  
Blastocyst Rate

Abstract The aim of this study was to evaluate the supplementation of Nerve Growth Factor (β-NGF) in the maturation medium in in vitro embryo production routines. Antral follicles were aspirated from ovaries of cows obtained from slaughterhouses and then oocytes were selected for quality (grades I and II) for in vitro maturation and subjected to 4 successive in vitro embryo production routines (IVEP). Supplementation of 100 ng of β-NGF was performed in the oocyte maturation medium 22 hours before in vitro fertilization. 48 hours after fertilization of the oocytes, an analysis was made of their cleavage rate by counting blastomeres with the aid of a stereoscopic microscope (cleavage rate = number of embryos / number of initial oocytes). Seven days after fertilization, the blastocyst rate was determined through the relation to the number of oocytes that started cleavage and reached this stage of development (blastocyst rate = number of blastocyst / number of oocytes that started cleavage). To verify the existence of a difference between the supplemented and the non-supplemented groups, the paired T test was applied, using the Excel / Action software (Microsoft). In vitro embryo production routines supplemented with β-NGF in the maturation medium had, on average, a higher cleavage rate (P = 0.0072) and a higher blastocyst rate (P = 0.0033) compared to non-supplemented routines with β-NGF. In this study was demonstrated that Nerve Growth Factor supplementation in the maturation medium improves the efficiency of in vitro embryo production in cattle, and this protein has a probable action in the oocyte maturation process.

scholarly journals Developmental competence and expression of the MATER and ZAR1 genes in immature bovine oocytes selected by brilliant cresyl blue

Zygote ◽  
2009 ◽  
Vol 18 (3) ◽  
pp. 209-216 ◽  
Author(s):  
Gustavo Bruno Mota ◽  
Ribrio Ivan Tavares Pereira Batista ◽  
Raquel Varella Serapião ◽  
Mariana Cortes Boité ◽  
João Henrique Moreira Viana ◽  
...  
Keyword(s):  
Developmental Competence ◽  
Control Group ◽  
Blue Dye ◽  
Brilliant Cresyl Blue ◽  
Immature Oocytes ◽  
Relative Expression ◽  
Cresyl Blue ◽  
Blastocyst Rate ◽  
Bovine Oocytes

SummaryThe objective of this work was to evaluate the selection of immature bovine oocytes by brilliant cresyl blue dye (BCB) and expression of transcripts MATER and ZAR1. Cumulus–oocyte complexes (COCs) from slaughterhouse ovaries were exposed to BCB diluted in mDPBS and incubated for 60 min at 38.5 °C in humidified air. After exposure those COCs were distributed in two groups, according to their cytoplasm colour: BCB+ (coloured cytoplasm) or BCB− (colourless cytoplasm). The control group was submitted to in vitro maturation (IVM) immediately after morphological selection and holding control group COCs were exposed to mDPBS without BCB but in the same incubation conditions of BCB+ and BCB− group. The COCs of all groups were submitted to IVM, in vitro fertilization (IVF) and in vitro culture (IVC). Cleavage rate (72 h post-insemination) was similar between control (65.3%) and BCB+ (64.4%) groups, but greater than (p < 0.05) holding control (49.8%) and BCB− (51.3%) groups. Blastocyst rate (192 h post-insemination) was not different between BCB+ (18.5%) and control (16.3%) groups, but greater (p < 0.05) than BCB− (8.4%) group. No difference was found for blastocyst rate between holding control group (14.2%), control and BCB+ groups. The relative expression of MATER and ZAR1 genes was evaluated by real-time PCR in immature oocytes collected from the control, holding control, BCB+ and BCB− groups. Despite the relative expression of MATER in holding control, BCB+ and BCB− were down regulated in comparison to control group there was no statistical difference (p > 0.05) in the relative expression of MATER and ZAR1 transcripts among groups. The results indicate that the BCB dye detects immature oocyte populations with different developmental competence, although no improvement in in vitro embryo production using oocytes exposed or not to BCB was observed. Development competence of immature oocytes exposed to BCB does not seem to be associated with variations in the expression of MATER and ZAR1 transcripts.

177 PERFORMANCE OF Gyr PREPUBERTAL HEIFERS IN IN VITRO EMBRYO PRODUCTION

2016 ◽  
Vol 28 (2) ◽  
pp. 219
Author(s):  
P. M. S. Rosa ◽  
A. J. R. Camargo ◽  
R. V. Serapião ◽  
L. S. A. Camargo ◽  
C. S. Oliveira
Keyword(s):  
Cleavage Rate ◽  
Embryo Production ◽  
Exact Test ◽  
Follicular Wave ◽  
Lactating Cows ◽  
In Vitro Embryo Production ◽  
Blastocyst Rate ◽  
Oocyte Donors ◽  
La Jolla

Bovine in vitro embryo production is highly relevant for dairy systems in Brazil, and Gyr dams are commonly used as oocyte donors. The aim of this study was to evaluate the use of prepubertal Gyr heifers as oocyte donors, an alternative to anticipate reproduction of those animals. For that, 11 Gyr [4 prepubertal (PP) donors and 7 adult cows © donors] were used in ovum pickup (OPU) sessions. The PP cows presented an average of 282.5 kg and 26.75 months, and had never displayed oestrous. Non-lactating cows presenting an average of 492 kg and 136 months were selected for C. Five replicates were performed, totaling 27 OPU sessions (C-17, PP-10) and 2–3 sessions per animal. Follicular wave was synchronised by aspiration of follicles larger than 8 mm 96 h before OPU. Cumulus-oocyte complexes (COC) were classified accordingly to their quality in viable (G1, G2, and G3) or non-viable (G4). Viable oocytes were matured and fertilized, and the presumptive zygotes were cultured in SOF medium at 38.5°C and 5% CO2 in air. Cleavage rate was assessed 48 to 72 h post-insemination (hpi) and blastocyst rate at 168 hpi. Mean number of structures was analysed by t-test, and percentage of viable, G1, G2, G3, G4, cleavage, and blastocyst rates were compared among groups by Fisher’s exact test (GraphPadInstat, La Jolla, CA, USA; P = 0.05). Results are followed by standard error values. All procedures were approved by a local ethics committee. We found that despite higher (P < 0.05) numbers for both viable oocytes (PP: 15 ± 2.6; C: 6.11 ± 0.76) and total oocytes (PP: 23.70 ± 2.83; C: 8.82 ± 1.19) in the PP group, the rate of viable oocytes was similar (P > 0.05) among PP and C groups (PP: 61.5 ± 6.51%, C: 66.79 ± 3.79%). Mean numbers of G1, G2, G3, and G4 oocytes were higher (P < 0.05) in the PP group (G1 = 7.1 ± 1.18; G2 = 4.9 ± 1.74; G3 = 3.9 ± 1.09; G4 = 7.8 ± 1.38) than in the C group (G1 = 2.70 ± 0.740; G2 = 2.47 ± 0.44; G3 = 1.11 ± 0.31; G4 = 2.52 ± 0.39). However, the proportion was similar (P > 0.05) among PP and C groups (PP: G1 = 29.5 ± 4.21%; G2 = 19.5 ± 2.85%; G3 = 15.9 ± 13.5%; G4 = 35.1 ± 6.33%; and C: G1 = 27.24 ± 4.44%; G2 = 29.60 ± 5.08%; G3 = 12.34 ± 3.01%, G4 = 30.79 ± 4.93%). Cleavage rate (PP: 91.3 ± 17.94%; C: 74.09 ± 4.65%), mean blastocyst number per OPU session (PP: 3.3 ± 1.29; C: 1.76 ± 0.28), and blastocyst rate (PP: 19.74 ± 7.40%; C: 27.03% ± 4.07%) were similar (P > 0.05) among groups. We conclude that prepubertal heifers presented increased numbers of viable oocytes per OPU session, but blastocyst yield was similar to adult cows. This data suggests that prepubertal Gyr heifers can be used as oocyte donors. Support from FAPERJ and Embrapa is acknowledged.

234 HORMONAL FOLLICLE STIMULATION IN HOLSTEIN COWS FOR IN VITRO EMBRYO PRODUCTION USING SPERM SORTED BY FLOW CYTOMETRY

2016 ◽  
Vol 28 (2) ◽  
pp. 248 ◽  
Author(s):  
L. Ferré ◽  
Y. Bogliotti ◽  
J. Chitwood ◽  
M. Kjelland ◽  
P. Ross
Keyword(s):  
Transvaginal Ultrasound ◽  
Prostaglandin F2α ◽  
Holstein Cows ◽  
Control Group ◽  
Hatching Rate ◽  
Embryo Production ◽  
In Vitro Embryo Production ◽  
Group 2 ◽  
Group 1

Transvaginal ultrasound needle-guided ovum pick-up (OPU) and in vitro embryo production (IVP) offer a reliable alternative to conventional embryo transfer to produce offspring. The success of OPU/IVP greatly depends on the number and quality of retrieved oocytes. The aim of this study was to compare OPU/IVP performance from stimulated Holstein cows. Holstein (Bos taurus) >8-year-old pluriparous open dry cows (n = 28) were used for OPU as oocyte donors. Follicular waves in all groups were synchronized by gonadotropin-releasing hormone (GnRH), prostaglandin F2α (PGF), and CIDR administrated on Day 0, followed by stimulation treatments 48 h later. No pre-synch was used. Total hormone dosage were administrated as follows: Group 1: pFSH = 180 mg (Folltropin, Bioniche, Belleville, ON, Canada; n = 7), Group 2: pFSH/LH = 500 IU (Pluset, Calier, Barcelona, Spain; n = 7), Group 3: eCG = 1500 IU (eCG, Biogénesis-Bagó, Buenos Aires, Argentina; n = 7) and Group 4: Control (n = 7), no stimulation. All injections were performed intramuscularly (i.m.) twice a day, during three days. OPU was performed 48 (Group 1) or 24 h (Group 2 and 3) after the last injection. The control group received saline solution i.m. Follicles were classified according to diameter in 4 categories: small (2–5 mm); medium (6–9 mm); large (10–14 mm) and extra large (>15 mm). A Mindray DP-30 Vet (Mindray Medical, Shenzhen, China) was equipped with a micro-convex transducer 5.0- to 8.5-MHz probe along with a disposable 21G needle. The OPU flow rate was 15 mL min–1. Retrieved oocytes were classified according to IETS guidelines as viable (grade 1 + 2) and non-viable (grade 3 + 4). The IVP protocol was according to that in Reprod. Fertil. Devel. (2004, 16, 253). Fertilization (Day 0) was carried out using female sex-sorted semen selected with a discontinuous density gradient (PureSperm, Nidacon, Mölndal, Sweden) and diluted to 1 × 106 sperm mL–1. ANOVA was used for comparisons of mean values and a chi-squared test was used for proportions. Results are presented in the Table 1. In conclusion, pFSH stimulation before ovum pick-up in Holstein cows increased the number of collected and viable oocytes, cleavage, embryo development, and hatching rates in comparison to other follicle stimulation hormones and non-stimulation. A cost-benefit analysis of these methods could be valuable in order to inform whether or not a stimulation protocol is necessary for a commercial IVP operation. Table 1.Numbers of follicles, collected and viable oocytes, cleavage rate, blastocysts and hatching rate

30 Vitrification of Equine Embryos: Application in a Commercial Cloning Program

2018 ◽  
Vol 30 (1) ◽  
pp. 154
Author(s):  
G. Vichera ◽  
R. Jordan ◽  
V. Arnold ◽  
D. Dobler ◽  
R. Olivera
Keyword(s):  
Breeding Season ◽  
Production Efficiency ◽  
Embryo Quality ◽  
Donor Cell ◽  
Blastocyst Stage ◽  
Pregnancy Rates ◽  
Embryo Production ◽  
In Vitro Embryo Production ◽  
The One

During a commercial horse cloning program, a critical point is the availability and maintenance of suitable recipient mares for a large quantity of embryo transfers. Usually, pregnancy rates and viable births off the breeding season decrease significantly, whereas the rate of in vitro embryo production remains constant. For this reason, an efficient vitrification system allows continuous embryo production throughout the year with the advantage of doing the transfers only during the breeding season. The vitrification technique evaluated in this study was the one described by Kuwayama et al. (2007 Theriogenology 67, 73-80). By using this method, we compared post-warming recovery efficiency, pregnancy rates, and viable foaling rates in 2 experimental groups: cloned blastocysts vitrified off-season and transferred in breeding season (VC, n = 337), and non-vitrified cloned blastocysts also transferred in breading season (no-VC, n = 516). To achieve this, equine oocytes were collected from slaughterhouse ovaries, matured, enucleated, and fused to a donor cell according to Olivera et al. (2016 PLoS One 11, e0164049, 10.1371/journal.pone.0164049). The reconstructed embryos (RE) were cultured in a well-of-the-well system by adding 3 RE per well for 7 to 8 days to reach the blastocyst stage, at which they were vitrified as mentioned above. During the breeding season, blastocysts were warmed and transferred in couples in a single cycling receptive mare. Pregnancies were confirmed by transrectal ultrasonography 15 days post-transfer. All variables were analysed by Fisher test (P < 0.05). The warming recovery rate was 91% (308/337) for cloned blastocysts. In addition, pregnancy and viable birth rates were similar for the VC and no-VC groups: 15.6% (24/154) v. 16.7% (43/258) for pregnancy rates, respectively, and 37.5% (9/24) v. 37.2% (16/43) for foaling rates, respectively. In summary, 9 viable cloned foals were obtained with off-season embryos warmed and transferred during the breeding season, showing that vitrification did not affect embryo quality. Hence, the proposed strategy provides the ability to maximize production efficiency of equine clones by generating a large number of pregnancies without stopping in vitro embryo production at any time of the year.

178 FIRST COMMERCIAL CATTLE IN VITRO EMBRYO PRODUCTION AND PREGNANCY RATES OF BOTH FRESH AND FROZEN IN VITRO EMBRYOS IN THE NORTH COAST OF PERU

2016 ◽  
Vol 28 (2) ◽  
pp. 220
Author(s):  
H. W. Vivanco-Mackie ◽  
R. D. Navarro ◽  
M. D. P. Salazar ◽  
E. A. Aguirre ◽  
G. B. Saldaña ◽  
...  
Keyword(s):  
Growth Factor ◽  
Pregnancy Rate ◽  
Artificial Insemination ◽  
North Coast ◽  
Embryo Production ◽  
The North ◽  
In Vitro Embryo Production ◽  
Blastocyst Rate ◽  
North Coast Of Peru

The objective of the study was to determine the pregnancy rate of fresh and frozen-thawed in vitro produced embryos transferred into recipients in the north coast of Peru. Artificial insemination results of frozen-thawed semen inseminated to cows in the same herd and season (summer) where the embryo transfers were performed was evaluated as control. For the in vitro embryo production, the rate obtained was 374 oocytes from 21 ovum pickup sessions (15.24 ± 8.91 oocytes/session). Of these oocytes, 246 were matured in bicarbonate buffered TCM-199 supplemented with 10% heat inactivated FCS as well as epidermal growth factor (EGF), insulin-like growth factor-1 (IGF-1), FSH, LH, oestradiol, and cysteamine for 24 h of incubation at 38.5°C, 5% CO2, and 90% humidity. The oocytes selected post-maturation were fertilised with the frozen-thawed sperm that was subjected post-thawing to Percoll gradient (90 and 45% Percoll), centrifugated, and resuspended in a TALP-IVF medium supplemented with 20 μM D-penicillamine, 10 μM hypotaurine, and 1 μM epinephrine. The oocytes were then inseminated with a concentration of 1.5 million sperm mL–1 in TALP IVF fertilization medium and incubated for 24 h at 38.5°C, 5% CO2, and 90% humidity. Subsequently, the presumptive zygotes were transferred to medium of 50 μL drops of SOFaa supplemented with 5% heat-inactivated FCS which was later replaced by SOFaa and 1% heat-inactivated FCS on Day 5 after fertilization. The embryos were inspected and graded on Days 7 and 8 post-fertilization and incubation at 38.5°C, 5% CO2 and 90% humidity. The blastocyst rate was evaluated on Day 7 post-fertilization. The blastocyst rate was 25.3% (21/83) and 4.19 ± 3.37 embryos per ovum pickup session were obtained. The embryo freezing media contained 1.5 M ethylene glycol as a cryo-protectant, and the method of thawing the embryo was the direct method (1 step). The pregnancy rate was compared by chi-squared analysis. The pregnancy rate for artificial insemination was 23.9% (1103/4612), and the pregnancy rate of fresh and frozen-thawed in in vitro embryos was 30% (13/43) and 20% (8/40), respectively (P > 0.05). Overall the pregnancy rates in the herd were relatively low, probably due the high environmental temperature during the season when the embryos were transferred and the semen was inseminated. Under those conditions, pregnancy rate was not affected by the use of fresh and frozen-thawed in vitro embryo transfer in comparison to the conventional artificial insemination of frozen semen in the coast north of Peru.

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