Development and testing of new embryo production components is important to improve the outcome following in vitro production of bovine embryos. The objective of this study was to compare media used in two bovine embryo production systems (control and EmbryoTrans Biotech: ETB). In Exp. 1, abattoir-derived cumulus-oocyte complexes were randomly assigned and in vitro matured (IVM) in either control [Medium 199 with Earles salts (Invitrogen, Carlsbad, CA, USA), supplemented with 10% fetal bovine serum (Hyclone, Logan, UT, USA), 1% penicillin/streptomycin (Invitrogen), 0.2 mM sodium pyruvate, 2 mM L-glutamine (Sigma Chemical Co., St. Louis, MO, USA), and 5.0 µg mL–1 of Folltropin®-V (Vetoquinol, Pullman, WA, USA)] or ETB BO-IVM medium for 21 to 24 h. IVF was conducted in 500 µL of pre-equilibrated modified Tyrode-lactate medium for control (Pryor et al. 2011 Theriogenology 75, 24–33) or ETB BO-IVF in Nunclon® 4-well multi-dishes (VWR Scientific, Pittsburgh, PA, USA). Seventeen hours post-insemination, presumptive zygotes were cleaned of cumulus cells and cultured in either Bovine Evolve (Zenith Biotech, Guilford, CT, USA) supplemented with 4 mg mL–1 of Probumin BSA (EMD Millipore, Norcross, GA, USA), under oil (Irvine Scientific, Santa Ana, CA, USA) or ETB BO-IVC medium under BO-oil for 7 days (8 days post-IVF). All cultures were performed at 38.5°C in a humidified atmosphere of 5% CO2, 5% O2, and 90% N2 using BT37 incubators (Planer Plc, Sunbury, UK). For Exp. 2, all conditions were maintained except a modified ETB BO-IVCA medium was used. On Day 8 of IVC, grade 1 and 2 blastocysts (BL) through hatching blastocysts (HBL) were counted and used to calculate total viable rates. In Exp. 2, these embryos were fixed in cold methanol, washed in PBS/0.1% Tween 20, mounted in 10 μg mL–1 Hoechst 33342/glycerol, and viewed under UV light to count cells (n = 49 and 107 for control and ETB, respectively). Each experiment was replicated 3 times with a total of 425 oocytes in Exp. 1 and 430 in Exp. 2, divided equally between treatments. Percentage data were transformed using arcsine square root function before analysis and means compared using a paired Student’s t-test. For Exp. 1, there were no differences in rates of cleavage or viable embryos between control and ETB systems (81.3% and 42.9% v. 80.5% and 48.4%, respectively). In Exp. 2, ETB was superior to control for percent viable, HBL, and combined HBL/expanded BL (51.9, 23.9, 45.8% v. 29.2, 5.8, 20.5, respectively; P < 0.05). Differences between mean cell counts for viable embryos were significant (control = 127.0 ± 6.7 s.e.m. and ETB = 162.7 ± 5.7; P < 0.0001). Embryo viability decreased in control media between Exp. 1 and 2 (42.9 v. 29.2%; P < 0.05). Seasonal differences may have contributed via heat stress with temperatures ranging from 23.8°C for Exp. 1 to 33.8°C for Exp. 2. Interestingly, embryo development in the ETB media did not decrease under the same conditions. In conclusion, ETB media produced more high-quality embryos than control under varying conditions experienced by commercial IVF companies.

The objective of this study was to reestablish an extinct strain of sheep that exhibits spontaneous X-linked factor VIII deficiency closely mimicking human hemophilia A. Twenty female carriers of the trait, produced in a previous study (Bormann et al. 2006 Reprod. Fertil. Dev. 18, 201–202), were backcrossed using 3 straws of semen from their affected sire using either IVF or multiple ovulation embryo transfer (MOET). Eleven oocyte donors were synchronized with CIDRs (15 days) and superovulated with a declining dose of FSH (204 mg) twice daily for 3.5 days. Nine MOET donors were synchronized using CIDRs (14 days), superovulated with a declining dose of FSH (184 mg) BID for 3 days with pregnant mare serum gonadotropin (PMSG; 200 IU) given with the final dose of FSH, and given 1000 IU of hCG 12 h post-CIDR removal. Recipient ewes were synchronized using sponges (Ovakron, HeriotAgvet, Rowville, Victoria, Australia) containing 30 mg of flugestone acetate (14 days) and given PMSG (400 IU) at sponge removal, followed by 1000 IU of hCG 12 h post-sponge removal. Oocytes were collected via follicular aspiration during midventral laparotomy and matured as previously reported. Semen for IVF was prepared by centrifugation on a Percoll gradient. Oocytes and sperm were incubated in mTALP with 20% estrus sheep serum (modified from Bavister et al. 1977 Bio. Reprod. 16, 228–237) for 20 h, then vortexed to remove cumulus cells, and cultured in G1.3 medium (Vitrolife, Englewood, CO) with BSA until transfer. Embryos were surgically transferred into oviducts of recipients 24 to 48 h following IVF. The 9 MOET donors were surgically inseminated at the uterotubal junction with approximately 1–2.0 106 spermatazoa. Oviducts of eight of these ewes were flushed 48 h post-insemination with warm M199 containing Hanks salts, 25 mm HEPES, 10% FBS, and 0.5 µg mL–1 gentamicin. MOET embryos were surgically transferred to synchronized recipients within 5 h. One MOET donor was not flushed due to poor response and did not produce an offspring. Utilizing 140 ova, IVF produced 54 embryos for an embryo/oocyte rate of 38.6%. All IVF embryos were transferred into 15 recipients resulting in 3 lambs for a lamb/embryo rate of 5.5%. The MOET donors produced 38 embryos and 13 apparently unfertilized ova, generating an embryo/oocyte rate of 74.5%. MOET embryos were transferred into 21 synchronized recipients. MOET produced 16 lambs for a lamb/embryo rate of 42.1%. Co-transfer of 1 IVF and 1 MOET embryo into a single recipient produced one offspring. Utilizing multiple reproductive technologies over a two-year period, 8 hemophilic offspring (7 females and 1 male), 6 carrier females, and 6 unaffected males were produced. This strain of sheep will be used to produce affected offspring for stem cell-based therapies.

In vitro-produced (IVP) bovine embryos are known to produce a lower pregnancy rate when compared to conventional in vivo-produced embryos. The inability of the IVP embryo to hatch from the zona pellucida (ZP) after embryo transfer is thought to be one contributing factor. This study was designed to evaluate the utilization of a microscope objective-mounted laser to cut the ZP to assist hatching prior to transfer into the recipient. Preliminary data were acquired to evaluate the effect of laser treatment on in vitro development and blastomere survival following treatment. In six replicates, bovine oocytes were in vitro-matured, fertilized, and cultured as per standard laboratory procedures (TransOva Genetics, Sioux Center, IA, USA). On Days 5, 6, and 7 of in vitro culture, embryos were randomly divided into 3 treatment groups: no treatment (Control; n = 63), sham ZP cut (Sham; n = 68), or ZP cut (Cut; n = 70). Control embryos were immediately returned to the incubator following selection. Sham embryos were exposed to all conditions as Cut except laser-assisted hatching. The XYClone system is a 300-mW, class 1 laser that emits a 3.5-µm beam at a wavelength of 1480 nm (Hamilton Thorne Biosciences, Beverly, MA, USA). This laser was used to produce the Cut group, using a pulse strength of 90% and pulse length of 600 µs. Embryos were returned to culture until Day 8 when rates of embryonic development and the percentage of live cells were determined. Chi-square was used to analyze all data. No significant effect of treatment or day of exposure was noted in either the total number of developing embryos or the ratio of live cells in each embryo. Mean live cells ranged from 89 to 96% across all treatments regardless of day of treatment. To investigate IVP embryo viability after laser-assisted hatching, commercially produced embryos (TransOva Genetics, Sioux Center, IA, USA) were randomly divided into two groups on the day of transfer, Control or Cut. The ZP of treated embryos were cut with slightly reduced laser exposure of 80% pulse strength and pulse length of 500 µs on Day 7, immediately prior to transfer into estrus-synchronized recipients. Pregnancy rates were determined via ultrasonagraphy at Day 30 (n = 337) and, due to the commercial nature of this project, only a subset of the Day 30 pregnant cows was checked at Day 60 (n = 289). The 30-day pregnancy rates were 49.2% and 54.1% for Control (n = 189) and Cut (n = 148) embryos, respectively, and were not statistically different (P > 0.05). However, at Day 60, the pregnancy rates for the Control (45.7%; n = 166) and Cut groups (57.7%; n = 123) were statistically different (P < 0.05). These results demonstrate that laser-assisted hatching using the XYClone system can improve 60-day pregnancy rates for in vitro-produced embryos.

In vitro culture of bovine embryos is usually associated with poor pregnancy rate following cryopreservation. The objective of this study was to compare the post-thaw viability of in vitro-produced bovine zygotes, cultured in vitro or in the reproductive tract of a host goat. Cumulus-oocyte complexes were matured in vitro, and in vitro fertilization was carried out with frozen-thawed semen as per standard laboratory procedures. At 18-20 h post-fertilization, zygotes were stripped of remaining cumulus cells and randomly separated into culture treatments. In three replicates, a total of 606 embryos were surgically transferred 12 to 24 h post-ovulation to the oviducts of an estrous-synchronized goat (VIVO) and 550 embryos were cultured in G1.3 for 72 h and then moved to G2.3 medium for 96 h and in a humidified atmosphere of 5% CO2, 5% O2, and 90% N2 (IVC). On Day 7, embryos were flushed from the excised tract with a 69.5% recovery rate or removed from culture. Embryos were classified according to IETS criteria with grades and stages recorded. All data were analyzed using the one-way analysis of variance and means were compared using Student's t-test. No differences were seen in the percentage of freezable quality embryos per total recovered between the two groups (34.3% vs. 32.3% for IVC and VIVO, respectively). However, there was a significant difference in the pre-freezing stage between the two culture groups (Stage 5.5 0.22 vs. Stage 4.8 0.26 for IVC and VIVO, respectively; P < 0.05), but no difference in the quality grade. All embryos greater than Stage 4, Grade 2 were frozen in groups of 5-10 in ethylene glycol with sucrose (Vigro Ethylene Glycol Freeze Plus; Bioniche Animal Health, Belleville, Ontario, Canada) in 0.25-mL straws. After thawing, embryo groups were washed, rehydrated, and incubated in G2.3 as above. Morphology was assessed by assigning grade and stage objectively at 24 h and 48 h post-thaw. Post-thaw viability in vitro was not different between groups (73.4% vs. 72.7% for IVC and VIVO, respectively). The average changes in morphology post-thaw from pre-freezing to 24 h and from 24 h to 48 h within each freezing group were determined. There was no significant difference in the mean change in stage (0.67 0.15 vs. 0.82 0.17 at 24 h and 0.31 0.09 vs. 0.37 0.10 at 48 h for IVC and VIVO, respectively) or grade (0.60 0.15 vs. 0.41 0.17 at 24 h and 0.03 0.06 vs. 0.14 0.07 at 48 h for IVC and VIVO, respectively) at either observation point. These results suggest that culture of in vitro-fertilized bovine embryos in the caprine reproductive tract did not alter post-thaw development or improve post thaw viability compared to in vitro cultured controls. However, morphological evaluation is too subjective to successfully predict pregnancy rate after transfer; therefore, further study is needed to determine if there are differences in pregnancy rates between these culture methods.

The objective of this study was to restore a line of sheep that exhibits spontaneous X-linked factor VIII deficiency closely mimicking human hemophilia A. Six straws of frozen semen from an affected Alpine White male were obtained from Switzerland. In the first experiment the straw of semen thawed was of poor quality. Two ewes were synchronized for use as embryo donors (MOET) by means of CIDRs for 14 days and superovulated with declining doses of FSH (184 mg) twice daily for 3 days. PMSG (200 IU) was given with the final dose of FSH and 1000 IU of hCG 12 h post-CIDR removal. The ewes were surgically inseminated 24 h later. Oviducts were flushed 48 h post-insemination producing 13 unfertilized ova (UFO). Spermatozoa were used for intracytoplasmic sperm injection (ICSI) utilizing oocytes collected from superstimulated ewes by laporatomy. These ewes were synchronized with CIDRs (15 days) and superovulated with a declining dose of FSH (204 mg) twice daily for 3.5 days. Utilizing 236 oocytes, ICSI produced 189 embryos, an 80% embryo/oocyte rate. Embryos were transferred surgically to the oviducts of 17 synchronized recipients. Recipients were synchronized using sponges (Ovakron; Heriot Agvet, Rowville, Victoria, Australia) containing 30 mg of flugestone acetate (14 days) and given PMSG (400 IU) at sponge removal, followed by 1000 IU of hCG 12 h post-sponge removal. Eleven recipients produced 17 lambs for a lamb/embryo rate of 8.9%. The straw of semen utilized for the second experiment was of higher quality. Three ewes were superstimulated for use as MOET donors, as above, with increased doses of FSH (228 mg) and PMSG (500 IU). Donors were surgically inseminated and oviductal flushes were performed 40 h post-insemination, yielding 19 UFO and 12 embryos for an embryo/oocyte rate of 38.7%. Embryos were transferred to four recipients, synchronized as above with an increased dose of PMSG (600 IU). These MOET recipients produced nine lambs for a lamb/embryo rate of 75%. Semen was used to produce embryos via in vitro fertilization (IVF) using oocytes collected from superstimulated ewes (as above with an increase of FSH to 252 mg). IVF produced 91 embryos from 247 oocytes for an embryo/oocyte rate of 36.8%. Embryos were transferred to 20 recipients 24 to 48 h post-fertilization. Seven recipients maintained pregnancy and produced 10 lambs with a lamb/embryo rate of 11%. ICSI was also utilized, producing 54 embryos from 98 oocytes, an embryo/oocyte rate of 55.1%. Embryos were transferred to eight recipients; none maintained pregnancy. Through the use of multiple reproductive technologies, 36 lambs (22 carriers) were produced from two straws of semen. Carriers will be bred back to their sire in a similar program to produce affected lambs. The authors would like to acknowledge J. Liu and M. Ridha for their contributions. This work was supported by NIH Grant HL073737-12.