87 EFFECT OF CRYOPROTECTANT CONCENTRATION IN THE VITRIFICATION SOLUTION ON THE ZONA PELLUCIDA HARDENING AND SPERMATOZOA PENETRATION OF BOVINE OOCYTES

In the murine model, it has been shown that the high concentration of cryoprotectants required for vitrification can activate the oocytes through a process mediated by calcium influx. This activation induces the zona pellucida (ZP) hardening and affects the sperm penetration. This study aimed to evaluate the effect of exposure of bovine oocytes to the vitrification solutions (VS1 and VS2) in calcium-free medium with 3 concentrations of etilenglycol (EG) and dimetylsulfoxide (DMSO) on the oocyte activation. Cumulus oocyte complexes (COC) were matured in vitro (22 h), partially denuded through pipetting in medium with hyaluronidase, and subject to four treatments: T1, untreated (control); T2, exposed to 20% EG+0% DMSO (VS1) and then 40% EG+0% DMSO (VS2); T3, 10% EG+10% DMSO (VS1) and then 20% EG+20% DMSO (VS2); and T4, 0% EG+20% DMSO (VS1) and then 0% EG+40% DMSO (VS2). The contact with each VS was 3 min and 30 s, respectively. After this, the COC were matured up to 24 h. In Expt. 1, COC were denuded and placed in a solution of pronase E in PBS (1 mg mL–1) to determine the number of oocytes with ZP digested after 9 min of exposure to the enzyme. In Expt. 2, COC were fertilized in TALP medium with 50 mg mL–1 heparin and 1 million mL–1 sperm. After 12 h, COC were denuded and stained with bisbenzimide (Hoechst 33342) and examined under epi-fluorescence. The number of oocytes indicating spermatic penetration was determined by presence of intact sperm heads, spermatic pro-nucleus, or 2 polar bodies. Data were analysed by the PROC GENMOD (SAS; see Table 1). In Expt. 1, there were no differences in the percentage of oocytes without ZP after pronase treatment in groups T1, T2, and T3. The T4 group had the lowest percentage of digestion, and T3 was not different from T4. In Expt. 2 there were no differences in the percentage of sperm penetration between T2, T3, and T4. All treatments had lower values than T1. In conclusion, bovine oocytes undergo hardening of the ZP when put in contact with the cryoprotectants, and this effect was significantly increased with the use of DMSO. Moreover, there was a decrease in sperm penetration in all treated groups, indicating that the natural blocking of polyspermy depends not only on the hardening of the ZP, but another process that could act at the plasma membrane. It is possible that cryoprotectants, regardless of their concentration, may trigger this early block through a mechanism that would be independent of calcium. Table 1.Effect of EG and DMSO concentration in the VS on the ZP hardening and sperm penetration of bovine oocytes exposed to these solutions Acknowledgment: the National Research Agency through the grant PICT 2007/1205.

Destete precoz y desempeño reproductivo en vacas tratadas con progesterona intravaginal

El objetivo del presente trabajo fue determinar el efecto del momento del destete precoz (DP) en vacas con cría tratadas con progesterona intravaginal sobre las características de la ovulación y la eficiencia reproductiva. Se realizaron 2 experimentos con animales de raza Hereford y Polled-Hereford. Exp.1: 38 vacas de baja condición corporal (3,3±0,8; media±DE; escala de 1 a 9) con 55,7±8,8 días posparto y Exp. 2: 35 vacas de alta condición corporal (5,4±0,9) con 57,5±15,9 días posparto. El día 0 todos los animales recibieron un dispositivo intravaginal (DIV) impregnado con 0,5 g de progesterona más 2 mg de benzoato de estradiol (BE; im). El día 8 se retiró el DIV, se aplicó 500 mg de cloprostenol sódico (im) y 24 horas después se aplicó 1 mg de BE. Los animales fueron distribuidos aleatoriamente a 4 tratamientos: T1): DP diez días antes de colocar el DIV; T2): DP el día de colocación del DIV; T3): DP el día del retiro del DIV y T4): Control con cría al pie. Todas las vacas fueron inseminadas a tiempo fijo a las 56 h del retiro de los DIV. En ambos experimentos se evaluó mediante ultrasonografía la dinámica folicular, el momento y distribución de las ovulaciones y la preñez. Se determinó la concentración plasmática de progesterona para evaluar la funcionalidad y la vida media del cuerpo lúteo generado por la ovulación inducida en los vientres que no resultaron preñados. En vacas de baja condición corporal (Exp.1), el diámetro del folículo dominante al retiro del DIV en el tratamiento T2 (11,2±2,5 mm) fue mayor (p

Control de la dinámica folicular ovárica en Llamas (Lama Glama) en posparto temprano

Se evaluó el efecto del acetato de medro-xiprogesterona (AMP, esponja intravaginal) con o sin inyección de benzoato de estradiol (BE) sobre el patrón de regresión folicular, la emergencia de la onda folicular y la tasa ovulatoria en llamas en posparto temprano y sin cría. El trabajo se realizó en la Estación Experimental de Altura del INTA de Abra Pampa, ubicada a 3484 msnm. Un total de 48 llamas adultas fueron categorizadas en lactancia temprana (n= 24, 30±4 días posparto, media±DE) y sin cría (n= 24). Cada hembra fue distribuida de acuerdo a la fase folicular (FF= crecimiento, estática o regresión) del folículo dominante (FD1) determinada por ultrasonografía ovárica desde 3 días previos al tratamiento. El día 0, todas las hembras recibieron una esponja intravaginal (150 mg de AMP) durante 8 días más 5 mg AMP (im) y la mitad de las hembras recibió aleatoriamente 2 mg de BE (im). Desde el día 0 hasta el 14, la respuesta ovárica fue monitoreada diariamente por ecografía. El día 12, las hembras que presentaron un folículo dominante ³6 mm (FD2) de una nueva onda folicular fueron tratadas con GnRH (8 mg, im) para inducir la ovulación. Se midió la concentración plasmática de 17b-estradiol (desde el día 0 al 8) y progesterona (día 14) para confirmar la ovulación. Se utilizó un diseño factorial 2x2x3 (estado lactacional, tratamiento con o sin BE y fases foliculares). Se observó interacción entre el estado lactacional y la fase folicular sobre el patrón de regresión del FD1, atribuida a una mayor duración en hembras sin cría (6,0 días) que en las hembras con cría (3,5 días) durante la fase estática. El día de emergencia del FD2 fue diferente (p

106 PREGNANCY RATE AFTER EMBRYO TRANSFER OF IN VIVO-PRODUCED OVINE EMBRYOS CRYOPRESERVED BY SLOW FREEZING OR VITRIFICATION

Although slow freezing is the method of choice to cryopreserve in vivo-produced ovine embryos, vitrification has became an alternative procedure mostly developed for in vitro-produced bovine embryos. The aim of this work was to compare pregnancy rates after cryopreservation of in vivo-produced ovine embryos with slow freezing or open pulled straw (OPS) vitrification method. Ewes were synchronized using intravaginal sponges containing 60 mg of medroxyprogesterone acetate for 14 d. Superovulation was performed using a total dose of 176 IU of ovine FSH (Ovagen), in 6 decreasing doses (i.m.) from Day 12 to 14 of treatment (Day 0 = sponge placing). Ewes were hand mated with 2 rams of proven fertility. Embryos were recovered 6 days after estrous detection by surgical procedure, evaluated under stereomicroscope, and randomly assigned to the cryopreservation treatments. Slow freezing was performed in D-PBS supplemented with 1.78 M ethylene glycol, 0.1 M sucrose, 4 mg mL-1 of BSA, and 20% serum. Embryos were loaded into 0.25-mL plastic straws and placed into a -7°C methanol bath chamber. After seeding embryos were cooled to -35°C at a rate of 0.5°C/min and then stored in liquid nitrogen. Thawing was performed by placing the straws in a 30°C water bath for 30 sec. Vitrification was performed by using the OPS method (Vajta et al. 1998) with minor modifications. Embryos were incubated in D-PBS supplemented with 1.78 M ethylene glycol, 1.3 M DMSO for 3 min and then transferred for 25 s in vitrification solution of D-PBS with 3.56 M ethylene glycol, 2.6 M DMSO, and 0.5 M sucrose, loaded in a 1 mL drop in the OPS, and immediately submerged into and stored in liquid nitrogen. Warming was performed in D-PBS plus 0.25 M sucrose for 5 min and then into D-PBS plus 0.15 M sucrose for another 5 min. Before embryo transfer, the presence of corpus luteum (CL) was detected by laparoscopic examination. One embryo per recipient was surgically transferred in the apical extreme of the uterine horn ipsilateral to the CL. Pregnancies were determined by ultrasonography 41 days after embryo transfer. Data were analyzed using the chi-square test. We found 47.8% pregnancy rate using slow freezing (11/23) and 43.5% pregnancy rate using OPS vitrification (10/23). Statistical differences were not detected (P = 0.09). We conclude that vitrification by OPS system, with minor modifications, is a suitable procedure for in vivo-produced ovine embryo cryopreservation.

111 EFFECT OF ETHYLENE GLYCOL IN VITRIFICATION MEDIUM ON BOVINE OOCYTE ACTIVATION AND IN VITRO EMBRYO PRODUCTION

In this study the effect of increasing ethylene glycol (EG) concentrations in the vitrification media (VM) and its relation with oocyte activation and in vitro embryo production were evaluated. Cumulus-oocytes complexes (COC) were matured in vitro for 22 h and then partially denuded by gently pipetting with hyaluronidase, and randomly assigned to 4 treatments: T1 = control group; T2 = COC exposed to 10% EG + 10% DMSO (VM1), 20% EG + 20% DMSO (VM2); T3 = 15% EG + 5% DMSO (VM1), 30% EG + 10% DMSO (VM2); T4 = 20% EG + 0% DMSO (VM1), 40% EG + 0% DMSO (VM2). Exposition to VM1 and VM2 lasted 3 min and 30 s, respectively. After treatment COC were incubated in maturation medium up to 24 h. In Experiment 1 COC were cultured for 24 h in fertilization TALP supplemented with 50 μg mL-1 of heparin, then completely denuded and cultured 24 h in CR1-aa. After this, oocytes were stained with bisbenzimide (Hoechst 33342) and the number of nuclei and cells were recorded. Structures presenting 2 cells or 2 nuclei were considered as activated oocytes. In Experiment 2 matured COC exposed to cryoprotectants as in Experiment 1 were fertilized and cultured for 6 days as previously described (Mucci et al. 2006). Variables analyzed included oocyte activation, cleavage rate at 48 h, and percentage of viable embryos at Day 7. Data were analyzed by PROC GENMOD (SAS Institute Inc., Cary, NC, USA). Activated oocytes percentage did not differ between EG concentrations in VM and were higher (T2, 24.7%, n = 101; T3, 25.0%, n = 96; T4, 30.2%, n = 119) compared with controls (T1, 9.8%, n = 61). In Experiment 2 no differences were found in cleavage rates (T1, 81.9%, n = 68; T2, 87%, n = 67; T3, 85.9%, n = 61; T4, 84.2%, n = 64) and Day 7 percentage of viable embryos (T1, 34.9%, n = 29; T2, 28.6%, n = 22; T3, 26.8%, n = 19; T4, 27.6%, n = 21) in treated COC. The exposition of COC to cryoprotectants per se could trigger oocyte activation in the range of 10 to 40%. Thanks toAdriana Cano (Instituto Nacional de Tecnología Agropecuaria) for contributions in statistical analysis.

438 REPEATED ULTRASOUND-GUIDED FOLLICULAR ASPIRATION IN PREGNANT SUCKLED BEEF COWS PRETREATED WITH OR WITHOUT eCG

In vivo oocyte recovery during the first trimester of pregnancy may be an alternative method of obtaining gametes for IVM/IVF/IVC from genetically valuable females. This study was conducted to evaluate i) the influence of the day of gestation on the follicular growth and number and quality of oocytes recovered by ovum pick-up (OPU) in pregnant suckled beef cows with or without eCG pre-stimulation, and ii) the possible effects on pregnancy outcome. Twelve pregnant suckled Angus cows (40 days after FTAI) were randomly assigned to 2 groups (n = 6/group). Group 1 treatment included: Day 0 = dominant follicle ablation (DFA) to synchronize the emergence of a new follicular wave, Day 1 = eCG treatment (2,000 IU, i.m. Syntex, Argentina) and Day 5 = OPU (follicles >3 mm were aspirated). Group 2: as for Group 1 with no eCG treatment. In both groups, OPU was repeated 5 times (Days 45, 59, 73, 87, and 101 of gestation) and ovarian follicles were classified into 3classes according to diameter (class I, <5 mm; class II, 5-9 mm; and class III, ≥10 mm). The collected COCs were categorized in 4 categories (I to IV) on the basis of both cumulus cells and appearance of oocyte cytoplasm. Categories I + II were considered as viable. Data were analyzed by PROC MIXED (SAS Institute, Cary, NC, USA). There was a significant treatment by follicular class interaction (P < 0.001). The numbers (mean ± SEM) of class II (4.3 ± 0.9) and III (2.5 ± 0.4) follicles/cow/session observed in eCG-treated cows were greater than for nontreated cows (0.9 ± 0.1 and 0.9 ± 0.1, respectively). In contrast, the number (mean ± SEM) of class I follicles/cow/session was lower for cows with eCG treatment (2.8 ± 0.4) than for nontreated cows (5.7 ± 0.5). A significant treatment by day of gestation interaction for aspirated follicles was observed (P = 0.03). The numbers (mean ± SEM) of recovered oocytes and viable oocytes/cow/session were greater (P < 0.05) for eCG-treated cows (2.2 ± 0.2 and 1.6 ± 0.4 respectively) than for nontreated cows (1.0 ± 0.2 and 0.9 ± 0.2, respectively). No donor pregnancies were lost either during or following OPU procedure. The overall efficiency of OPU procedure is shown in Table 1. We can conclude that (1) eCG-treated pregnant suckled cows can be a source of oocytes for IVF to at least 100 days of gestation and (2) repeated DFA/eCG treatment/OPU procedures did not affect the pregnancy outcome. Table 1.Overall efficiency of repeated DFA/eCG treatment/OPU procedures in pregnant suckled cows

Simplified superovulatory treatments in Corriedale ewes

Two experiments were designed to evaluate the possibility of simplifying superovulatory treatments in Corriedale ewes with use of ovine FSH (oFSH). Ewes received intravaginal progestogen sponges for 14 days. In Experiment 1, several simplified schedules were tested. Ewes were treated with 176 NIH-FSH-S1 units' oFSH given as a single injection in saline, along with 500 IU eCG 48 h before sponge removal (Group A1), in four equal doses (B1), or given as a single injection in a polyvinylpyrrolidone vehicle (C1) 24 h before sponge removal. In Experiment 2, the simplified protocol that exhibited the most desirable results in Experiment 1 (A2) was compared with the same protocol, but using less oFSH (132 units) (B2) and with the most conventional protocol (176 units of oFSH in eight decreasing doses; C2). Estrus was detected and ewes were naturally mated. The ovarian response and embryo production were assessed on Day 6 after estrus. LH was measured at 6h intervals from pessary withdrawal. The onset of estrus and the pre-ovulatory LH surge were advanced (P<0.05) in ewes treated with FSH and eCG. In Experiment 1, protocol A1 produced a greater percentage of superovulated ewes compared to C1 (100.0 compared with 58.3%; P<0.05), increased ovulation rate (13.8 corpora lutea compared with 6.2 and 4.7 for B1 and C1, respectively; P<0.05), and tended to increase the number of transferable embryos compared to B1 (P=0.08). In Experiment 2, percentages of superovulated ewes and ovulation rates were similar among groups; however, Group A2 tended to have more large follicles (P=0.07) than C2. The number of transferable embryos was similar among the three treatments. In conclusion, the reduced-dose oFSH given once along with eCG is the most appropriate superovulatory treatment because it combines simplicity and a lesser dose of gonadotropin, which also implies a reduction in cost, without reducing embryo production.

Multiple ovulation and embryo transfer with fresh, frozen and vitrified red deer (Cervus elaphus) embryos in Argentina

Two multiple ovulation and embryo transfer (MOET) programs with fresh, frozen and vitrified red deer embryos were carried out during the reproductive season of 2005 and 2006 in a local breeding farm in Argentina. Multiparous (n=10 and 9, respectively) weaned hinds were used as donors for each year. The estrous synchronization treatment of donors and recipients consisted of inserting an ovine intravaginal sponge containing medroxiprogesterone acetate (MAP) for 12 days. Superovulation was conducted with a total dose of 180 mg of NIH-FSH-P1 (Folltropin-V, Bioniche, Belleville, Ontario, Canada), given i.m. in eight decreasing doses every 12h (40, 40; 27, 27; 15, 15; 8, 8 mg), from days 10 to 13. Donor females were mated with one stag of proven fertility. The recovery rate was 84.1% (122/145), obtaining 45.1% (55/122) of transferable embryos, 24.6% (30/122) of degenerated embryos and 30.3% (37/122) of unfertilized oocytes. Pregnancy rates after transfer of fresh, OPS vitrified/warmed and ethylene glycol (EG) frozen/thawed embryos were 64.3% (18/28), 53.3% (8/15) and 70.0% (7/10), respectively. Vitrification and freezing with ethylene glycol procedures constitute an interesting alternative for red deer embryo cryopreservation.

132 SUCCESSFUL EMBRYO TRANSFER OF IN VIVO-PRODUCED RED DEER (CERVUS ELAPHUS) EMBRYOS AFTER CRYOPRESERVATION BY SLOW FREEZING OR VITRIFICATION

Multiple ovulation and embryo transfer (MOET) programs for red deer (Cervus elaphus) have been established commercially over the last decade, with embryo cryopreservation being a related practice necessary to enhance the use of valuable genetic information. The aim of this work was to establish alternative methods for red deer embryo cryopreservation by using slow freezing with ethylene glycol (SF–EG) and vitrification by open pulled straw (OPS) methods. After surgical flushing of 18 superstimulated donors, 54 transferable embryos were recovered; 28 were transferred fresh to synchronized recipients and the others were cryopreserved by SF–EG (n = 11) or OPS (n = 15), respectively thawed or warmed, and transferred to recipients. Fresh embryos were maintained in Dulbecco's PBS + 20% cow serum (holding medium, HM) until transfer (maximum 3 h after collection). SF–EG cryopreserved embryos were suspended in HM + 1.78 M EG + 0.1 M sucrose + 4 mg mL−1 BSA. After a 10-min equilibration, embryos were loaded individually into 0.25-mL plastic straws and placed into a −7°C methanol bath chamber. After seeding (5 min later), the straws were cooled from −7 to −35°C at a rate of 0.5°C min. Straws were plunged into and stored in liquid nitrogen. Thawing was performed by placing the straws in a 30°C water bath for 30 s; their contents were drained into HM until transfer. Embryos were vitrified using the OPS method with minor modifications. They were first incubated in HM + 1.78 M EG + 1.3 M DMSO for 3 min and then transferred for 25 s into a vitrification solution of HM + 3.56 M EG + 2.6 M DMSO + 0.5 M sucrose. Each embryo was loaded by touching a 1-µL drop with the straw, which was immediately submerged into and stored in liquid nitrogen. Warming was done by placing the narrow end of the straws into HM + 0.25 M sucrose for 5 min. Embryos were then transferred into HM + 0.15 M sucrose for 5 min and finally to HM until transfer. Both types of cryopreserved embryos were transferred a few hours after collection, immediately after thawing or warming. Before embryo transfer, the presence of corpus luteum (CL) of recipients was confirmed by laparoscopic examination. Each embryo was surgically transferred into the apical extreme of the uterine horn ipsilateral to the CL of one recipient. Pregnancy was determined by ultrasonography 41 days after embryo transfer. The pregnancy rate between groups was compared with the chi-square test (P &lt; 0.05). No statistical differences were found between groups (Table 1). Our results show that both vitrification and slow freezing methods with EG are suitable to cryopreserve red deer embryos. Table 1. Pregnancy rates in recipient hinds after transfer of fresh, vitrified, or frozen red deer embryos

125 IN VITRO-PRODUCED BOVINE EMBRYOS VITRIFIED IN GLASS CAPILLARIES USING TCM-199 OR DULBECCO'S PHOSPHATE-BUFFERED SALINE AS VITRIFICATION-WARMING MEDIA

In previous studies (unpublished data) we observed that the replacement of open pulled straws (OPS) with glass capillaries (GC) did not affect the embryo survival rate after vitrification–warming. The aim of this work was to evaluate the post-Cryopreservation survival rate of in vitro-produced bovine blastocysts (B) and expanded blastocysts (eB) using Dulbecco&apos;s phosphate-buffered saline (PBS) or TCM-199 (TCM; Sigma-Aldrich, St Louis, MO, USA) as holding medium during vitrification and warming in glass capillaries. Cumulus–oocyte complexes were in vitro-matured and fertilized as previously described (Mucci et al. 2006 Theriogenology 65, 1551–1562), and cultured in 4 well plates in groups of 50 in 400-�L drops in serum-free CR1aa under low oxygen condition. Grade B1, B2, and eB were selected at Day 7 post-insemination and allocated to 3 groups: vitrification in TCM, vitrification in PBS, and control (without vitrification). Vitrification and warming were performed according to Vajta et al. (1998, Mol. Reprod. Dev. 51, 53–58), replacing OPS with GC (Tecnon Argentina S.A., Buenos Aires, Argentina); 75 mM length, 1.4 mM internal diameter, 1.6 mM external diameter). Briefly, B and eB were incubated in 1.78 M ethylene glycol (EG) and 1.3 M dimethyl sulfoxide (DMSO) in TCM or PBS supplemented with 20% estrous cow serum (ECS) for 3 min. Embryos were then transferred for 25 s to TCM or PBS supplemented with 3.56 M EG, 2.6 M DMSO, 0.5 M sucrose, and 20% ECS (vitrification solution: VS). Loading of embryos (2 per capillary) was performed by touching a 1-�L drop of VS with the capillary. After this, each capillary was immediately submerged into and stored in liquid nitrogen. Warming was performed by placing the capillary tip directly into TCM or PBS supplemented with 0.25 M sucrose for 5 min. Embryos were then transferred to TCM or PBS containing 0.15 M sucrose and 20% ECS for 1 min. After warming, embryos were cultured for 72 h in CR1aa + 5% ECS to evaluate embryo survival (hatching rate). Data was analyzed using the CATMOD procedure (SAS Institute, Inc., Cary, NC, USA). No interaction was found between holding media and embryo stage. Vitrified-warmed embryos had a significantly lower hatching rate compared with the control group (P &lt; 0.05), whereas no differences were found between TCM and PBS. Expanded blastocysts had a higher hatching rate than blastocysts (P &lt; 0.05). In conclusion, TCM can be replaced with PBS for its use in vitrification procedures. This protocol modification allows a simplified use of this technique in field conditions.

Integrated morphophysiological assessment of two methods for sperm selection in bovine embryo production in vitro

Extensive work was done regarding the ability of Swim up and Percoll gradient to select functional sperm for in vitro embryo production (IVP) systems. The aim of this work was to compare Swim up and Percoll as methods of sperm selection by ultrastructural, biochemical and functional studies. Frozen-thawed semen from two bulls (Experiments 1 and 2, respectively) were treated using Swim up or Percoll discontinuous gradients. Motility, sperm membrane ultrastructure, sperm proteins, in vitro embryo production (insemination doses, cleavage, embryo yield and quality) and embryo sex ratio were scored and compared. Electron transmission microscopy of outer sperm membranes showed higher (P<0.05) percentage of sperm with lost acrosomes in Percoll treated samples compared to Swim up. A differential protein pattern was also detected. When in vitro embryo production was performed, Percoll gradient produced higher (P<0.05) number of fertilizing doses (7.6 versus 5.9, Bull 1; 13.5 versus 7.8, Bull 2) and higher sperm motility (90% versus 76.6%, Bull 1; 81.7% versus 68.3%, Bull 2) than Swim up. The percentage of cleavage (Day 3) was similar in both treatment groups, whereas embryo production rate (Day 7) was higher (39.4% versus 30.2%, Bull 1; 38% versus 32.4%, Bull 2; P<0.05) when Percoll gradient was used. The percentage of hatched embryos (Day 11) and sex ratio did not differ. Total cell counting and embryo differential staining (inner cell mass and trophoblast cells) of Day 7 embryos showed that Percoll treated sperm produced better quality embryos compared to Swim up. We concluded that Percoll had a better performance selecting sperm and an enhanced capacity for embryo production when compared with the Swim up procedure; this could be attributed to a better acrosome exocytosis, associated to the absence of certain membrane proteins.

Effect of estrous cow serum during bovine embryo culture on blastocyst development and cryotolerance after slow freezing or vitrification

The present study investigated the effect of estrous cow serum (ECS) during culture of bovine embryos on blastocyst development and survival after cryopreservation by slow freezing or vitrification. Embryos were derived from in vitro maturation (IVM) and in vitro fertilization (IVF) of abbatoir-derived oocytes. At Day 3, embryos were cultured in three different media: Charles Ronsenkrans medium + amino acids (CR1aa; without bovine serum albumin (BSA)) + 5% estrous cow serum (CR1-ECS), CR1aa + 3 mg/mL BSA (CR1-BSA) or CR1aa + 5% ECS + 3 mg/mL BSA (CR1-ECS-BSA). At 7.5 d post-insemination (PI), blastocyst yield and quality were evaluated; blastocysts and expanded blastocysts from each media were cryopreserved by Open Pulled Straw (OPS) vitrification method or slow freezing (1.5 M ethylene glycol, EM). Total blastocyst yield did not differ among CR1-ECS, CR1-BSA and CR1-ECS-BSA (30.9, 33.1 and 32.9%, respectively, P < 0.05). Embryo survival (hatching rate) was higher in vitrified versus slow-frozen embryos (43% versus 12%, respectively, P < 0.01), and in embryos cultured in CR1-BSA (40.3%) compared with those cultured in serum-containing media (CR1-ECS, 21.5% and CR1-ECS-BSA, 19.8%; P < 0.01).

IN CONCLUSION

(a) it was possible to produce in vitro bovine embryos in serum-free culture medium without affecting blastocyst yield and quality; (b) serum-free medium produced the best quality embryos (in terms of post-cryopreservation survival); and (c) vitrification yielded the highest post-cryopreservation survival rates, regardless of the presence of serum in the culture medium.

Fetal mortality diagnosis by ultrasound in the vicuña (Vicugna vicugna)

Ultrasonography is widely used in domestic species of camelids, but there is no information about the use of this technique for pregnancy diagnosis and determination of embryonic or fetal losses in the vicuña (Vicugna vicugna). The study was performed in 202 vicuñas (3-year-old females, n = 31; adult females, n = 171) mated during the summer months (January through March 2001) at the Abra Pampa Experimental Farm of Altitude in north-west Argentina. Transrectal ultrasound examination was performed in May (estimated 40-120 days of gestation) to determine the number of pregnant females. The pregnancy rate was 45.5% (92/202). No significant difference (P > 0.05) was observed between the pregnancy rate of 3-year-old females (41.9%) and adult females (46.2%). In December (estimated 250-330 days of gestation) of the same year, a second ultrasonographic study was performed on those vicuñas that were diagnosed as pregnant from the first ultrasound scan. Of 92 animals diagnosed as pregnant in May, only 84 were present in December, because eight females died in the period of study. Overall, 11.9% (10/84) of fetuses were lost during the period (18.1% in 3-year-old vicuñas and 10.9% in adult vicuñas). In conclusion, transrectal ultrasonography was found to provide a rapid and non-invasive means for pregnancy and fetal mortality diagnosis in vicuñas.

Successful transfer of vitrified Ilama (Lama glama) embryos

The exploitation of the domestic animals species of South American camelids is of great social importance for the native people living in the High Andes. The reproductive physiology of these species is a unique challenge in the development of advanced breeding techniques. At present, the cryopreservation of embryos has not been developed and very few investigations have been conducted. The objective of the present work was to evaluate the in vivo survival of vitrified llama embryos after transfer to recipient females. Donors females were treated with a CIDR-estradiol benzoate-eCG regimen and were mated naturally 6 days after CIDR withdrawal. One ovulatory dose (8 microg) of GnRH was administered immediately after mating. A second mating was allowed 24 h later. Embryo recovery was performed nonsurgically between 8 and 8.5 days after the first mating. Twenty-two ova/embryos were recovered from 12 donor females. Hatched blastocysts were exposed to vitrification solution (20% glycerol + 20% ethylene glycol + 0.3 M sucrose + 0.375 M glucose + 3% polyethylene glycol (P/V)) in three steps, and after loading into 0.25 ml straws, were plunged into liquid nitrogen. For embryo transfer, recipients animals were ovulation-synchronized using GnRH administered at the same time as donors. A total of eight vitrified-warmed embryos and 12 fresh embryos were nonsurgically transferred to four and six recipient females, respectively (two embryo per recipient). The pregnancy rates were 50 and 33.3% for recipients that had received vitrified embryos and fresh embryos, respectively. The results demonstrated the effectiveness of this simple vitrification method for cryopreservation of llama embryos.

Evaluation of two treatments in superovulation of mares

The efficiency of superovulating mares with an enriched fraction of equine follicle-stimulating hormone (feFSH) and an equine pituitary extract (EPE) with similar FSH content but differing in the LH amount was compared. Mares were randomly assigned to an feFSH (n = 5) or EPE (n = 5) treatment. The experimental period was of 2 successive estrous cycles, with the first cycle as the control. At Days 6 and 7 of the estrous cycle, the mares received 250 micrograms i.m. cloprostenol. The treatments consisted of daily injections of 25 mg feFSH or EPE beginning on Day 6 post ovulation. Mares were inseminated every other day until the last ovulation was detected. When the mares in the control and treatment cycles developed at least 1 or 2 > or = 35-mm follicle, respectively, the treatment was interrupted, and a single injection of EPE (25 mg, i.v.) was administered to induce ovulation(s). Nonsurgical embryo recovery was performed 6 or 7 d after ovulation in both control and treatment cycles. The number of ovulations per mare was not significantly different (P > 0.05) between feFSH and EPE groups, but both were higher (P < 0.05) than that of the control cycle. The number of recovered embryos per ovulation was similar (P > 0.05) for control, feFSH and EPE groups. The high amount of LH presented in EPE did not affect the superovulatory response of the mares. Superovulatory treatments increased the ovulation rate of mares but did not affect the embryo recovery rate per ovulation.