Successful embryo transfer in Tianzhu white yak using standard protocol

The present study was carried out to investigate the efficiency of superovulation, oestrus synchronization, and embryo recovery in Tianzhu white yaks and also to confirm the pregnancy rate of black yaks, to which embryos collected from white yaks were transplanted. Forty-seven yaks were selected from different experiment groups, including 10 Tianzhu white female yaks (donor, group A) and 37 black female yaks (recipient, groups B and C). Superovulation of the donor was induced by the application procedure of CIDR-B + FSH + PG. Oestrus synchronization of recipients was induced using two methods: group B was given the same treatment as group A, except that the follicle-stimulating hormone (FSH) injection was not administered, whereas group C was injected with cloprostenol only once when corpus luteum (corpora lutea) was (were) palpated. The results showed that the oestrous rates in group A were higher (80%) than those in group B (60%) and group C (44.5%). As for the efficiency of superovulation, it was indicated that the mean numbers (±SD) of total corpora lutea, follicles, viable (transferable), and degenerated embryos were 4.75 ± 2.19, 1.13 ± 0.83, 2.50 ± 1.31, and 1.38 ± 0.92, respectively. The mean embryo recovery rates were 55.6%. All together, 18 viable embryos of Tianzhu white yak were obtained and 12 of them were transplanted to 10 recipients. The pregnancy rate was 50% and the delivery rate was 40%.     

Effect of the luteinizing hormone on embryo production in superovulated rabbit does

For most domestic animals, the responses to superovulation treatments are not controlled as a consequence of the lack of knowledge on exogenous gonadotrophins effects on the ovarian function. The role of luteinizing hormone (LH) on the number and quality of embryos produced was evaluated on rabbit does superovulated with porcine FSH (pFSH). Parameters of embryos recovery, in vitro and in vivo embryo development rates after freezing/thawing were compared. We used three experimental groups: (1) control group without superovulation treatment, (2) "pFSH+pLH" and (3) "pFSH" groups where females were treated with pFSH, respectively, with (20%) or without (0%) porcine LH supplementation. The number of corpora lutea and the number of embryos produced were significantly higher (p<0.001) in superovulated does than in control group (27.1, 26.7 versus 11.9 corpora lutea and 20.3, 21.2 versus 9.6 embryos produced for pFSH+pLH, pFSH and control group, respectively). However, both gonadotrophins administrations (groups 2 and 3) led to defaults of ovulation when compared with untreated does. No significant difference was observed between the number and quality of the embryos produced by does treated with pFSH+pLH or with pFSH alone. Moreover, we observed no significant difference between results of in vivo and in vitro viability assays after thawing. We concluded that pFSH alone seems to be sufficient to stimulate the follicles growth and that exogenous pLH administrated has no effect on the quantity and quality of embryos. Further studies are needed to evaluate the hormonal patterns before and after the gonadotrophins injections in the rabbit species.     

Comprehensive investigation of nucleotide diverdity in yaks

To understand the maternal genetic diversity of Tianzhu white yak better, we analyzed mtDNA D‐loop sequences of 209 Tianzhu white yaks, which are from the central region of Tianzhu white yak habitat. Accordingly, a total of 45 haplotypes were identified in Tianzhu white yaks in this study, and 18 of them were unique. The nucleotide diversity and haplotype diversity of population studied were 0.024 ± 0.003 and 0.946 ± 0.007 respectively, revealing that Tianzhu white yak possess a relatively high genetic diversity. The phylogenetic analysis, combining D‐loop sequences in this study with 533 previous published D‐loop sequences of 13 yak breeds, indicated that Tianzhu white yaks fell mainly into haplogroup A and that a small portion belonged to haplogroups B, C, D and E. Moreover, six haplotypes of 20 individuals identified in Tianzhu white yak were in the taurine haplogroup, indicating hybridization between Bos taurus and Tianzhu white yaks. In summary, this study supplies a comprehensive maternal genetic pattern for Tianzhu white yak and provides a basic reference for future breeding programs to conserve the purebred Tianzhu white yak.     

Superovulatory responses in FSH- or Pergonal®-treated heifers

Follicle stimulating hormone (FSH) or human menopausal gonadotropin (Pergonal^®) were used in combination with prostaglandin F_2α (injected either intramuscularly or intravenously) to induce superovulation in 32 beef heifers. Two different transfer media (phosphate buffered saline [PBS] + 20% fetal calf serum, or PBS + 1.5% bovine serum albumin) and two different nonsurgical transfer instruments (stainless steel tube with polyethylene tubing and Cassou gun) were used to transfer embryos to recipient cows. There were no significant differences (P>0.10) in the number of corpora lutea, oocyte or embryos recovered, and transferable embryos (good morula and blastocysts) after superovulation with either gonadotropin. More pregnancies (P<0.10) resulted with non-surgical transfer of embryos from FSH- than Pergonal^®-primed donors (29% vs 13%, respectively). However, pregnancy rates were not affected by the two transfer media or transfer instruments used in this study.     

Comparison of once daily and twice daily FSH injections for superovulating beef cattle

Twelve cycling Angus-based crossbred cows were used in a crossover experimental design to evaluate two different injection schedules using Follicle Stimulating Hormone (FSH) for superovulating donor cattle. Females randomly assigned to Treatment (A) were given twice daily FSH injections of 5 mg each (12 hours apart) for five consecutive days starting on day 10 of the estrous cycle while those in Treatment (B) received the same daily dose level of FSH, except it was given in a 3.2% protein gelatin carrier vehicle and administered on a once daily injection schedule. Animals in both Treatments (A) and (B) were each given a 30 mg dose of commercially available prostaglandin-F(2alpha) agent 48 hours after the first FSH injection. Cows in estrus were initially handmated to a fertile bull then artificially inseminated 12 hours later with two units of frozen semen. All 12 animals (100%) given twice daily FSH injections and 11 of the females (91.6%) administered once daily FSH injections exhibited standing estrus within 5 days following injection of the luteolytic agent. On day 7 or 8 after the onset of standing estrus a laparotomy was performed to observe ovarian structures. When the superovulation response was evaluated, the mean number of corpora lutea per ovary ranged from 2.9 in the twice daily injection group to 4.1 in the once daily injected group. Unexpectedly, the once daily treated group had significantly more corpora lutea per animal (8.1 vs. 6.4) than those in the twice daily treated group. In addition, mean ovarian size score per animal increased significantly when pre-treatment scores were compared to those recorded following FSH treatment (laparotomy) in both Treatment (A) and (B), however, the post-treatment ovarian size scores were not different between these groups. When evaluating post-treatment follicular development, the once daily injection group had significantly more smaller follicles (<10 mm) and a greater number of ovulatory size follicles (>10 mm) than the twice daily injection group. Furthermore, viable appearing embryos were recovered from both treatment groups and no adverse reactions were observed with the gelatin carrier vehicle in Treatment (B). Since the once daily FSH injection schedule resulted in a superovulatory response equal to or greater than the twice daily FSH injection schedule, this approach to superovulation should not be overlooked by those involved in bovine embryo transplantation.     

Transfer of superovulated sheep embryos obtained with different FSH-P

Embryo transfer is one way of accelerating genetic improvement in sheep. One of the main obstacles has been the production of good-quality embryos. The use of progestagens and the stimulation of ovulation with follicle stimulating hormone pituitary extract (FSH-P) has permitted the superovulation of donor and recipient ewes and the synchronization of their cycles. The injection of 16 mg FSH-P at the end of progestin treatment gave means of 9 +/- 1.5, 12 +/- 1.5, and 19.5 +/- 2.6 corpora lutea per ewes in the Préalpes, Lacaune, and Romanov x Préalpes breeds respectively (this last breed is particularly prolific). Twenty Préalpes donor ewes produced 133 embryos that were recovered surgically at Day 6 of gestation; of these, 99 morulae were transferable. Forty-five morulae transferred surgically into 24 Préalpes recipient ewes yielded 16 pregnant ewes and 27 lambs (1.7 per ewe). Twenty-two Lacaune ewes yielded 204 embryos, of which 152 morulae were transferable. Of 76 recipients, 58 became pregnant and gave birth to 97 lambs (1.7 per ewe). During anoestrus, the mean ovulation rate decreased from 11.2 to 8.4; 40.6% of the embryos recovered were of transferable quality versus 74.5% during the normal breeding season. An improved superovulation technique, based on the use of FSH-P with a known follicle stimulating hormone to luteinizing hormonal (FSH/LH) ratio, provided us with good-quality embryos. This treatment must be adapted to the season.     

Comparison of three protocols for superovulation of brown brocket deer (Mazama gouazoubira)

This study aims to evaluate the ovulation rate and the presence of functional corpora lutea after treatment by three different protocols designed to cause superovulation in brown brocket deer. Six female received an intravaginal device containing 0.33 g of progesterone (CIDR®) for 8 days, followed by 0.5 mg injection of estradiol benzoate at the time of insertion and 265 µg of cloprostenol at the time of removal. Afterwards, the hinds were divided into three groups (n = 2): Treatment A received injection of 600 IU eCG on Day 4 after CIDR® insertion; Treatment B received injection of 300 IU eCG at the same time; and Treatment C received injection of 250 IU FSH dissolved in PVP, also on Day 4 post‐insertion. The treatments were crossed over with 44–48 day intervals after CIDR® removal, such that all the deer were submitted to all three treatments. The mean ovulation rate (Treatment A = 3.40 ± 0.68, Treatment B = 1.40 ± 0.24, Treatment C = 0.80 ± 0.49), total ovarian stimulation (Treatment A = 4.80 ± 1.02, Treatment B = 1.80 ± 0.37, Treatment C = 1.40 ± 0.60), and mean CL diameter (Treatment A = 7.33 ± 0.76 mm, Treatment B = 3.94 ± 0.19 mm, Treatment C = 2.18 ± 0.49 mm) in Treatment A were significantly higher than the mean ovulation rates, total ovarian stimulation, and mean CL diameter in Treatments B and C. The mean fecal progesterone metabolites at the luteal phase in Treatment A (6,277.94±2,232.47 ng/g feces) was significantly different from Treatment C (1,374.82±401.77 ng/g feces). Thus, although fertility was not evaluated directly, Treatment A proved capable of induce superovulation in the species Mazama gouazoubira, presenting the greatest mean ovulation rates, with the formation of functional corpora lutea. lutea. Zoo Biol 31:642‐655, 2012. © 2011 Wiley Periodicals, Inc.     

FSH is superior to eCG for promoting ovarian response in Chinese Bamei gilts

The Bamei gilt is a Chinese native breed located in northwest China, which adapts to the extremely dry and cold environment and is distinguished for its excellent reproductive and maternal characters. To ensure sufficient numbers of embryos for transgenic and nuclear transfer research, hormonal induction of gilt estrus and superovulation may be necessary. The objective of this study was to compare the superovulation effects of equine chorionic gonadotropin (eCG, Group A) and FSH (Groups B-D) in Chinese Bamei gilts. The results show that though eCG could produce more corpora lutea (CL, 14.3) than the control (CL, 9.2), and the FSH treatments had significantly increased the number of CL compared with the eCG treatment. Within the different FSH protocols, the numbers of CL were significantly greater in Groups B (CL, 77.8) and C (CL, 66.8) than in Group D (CL, 42.7), however, ovarian cysts were observed in Groups B and C, but not in Group D. These data suggest that Group D (280 IU FSH) is a suitable protocol to facilitate the development of ovarian follicles and increase the number of useful embryos per gilt for embryos recovery. The optimal FSH protocol of superovulation in Bamei gilts appears to be: D13/100 IU, D14/80 IU, D15/60 IU, D16/40 IU plus prostaglandin (PG) 0.2mg, D17/hCG 1000 IU.     

Good quality sheep embryos produced by superovulation treatment without the use of progesterone devices

Multiple ovulation and embryo transfer (MOET) is a very important tool for the genetic improvement and preservation of endangered livestock. However, the success of a MOET programme highly depends on the number of transferable embryos in response to a superovulation treatment. Thus, the aim of this study was to compare the number and quality of embryos produced during natural oestrus under porcine FSH treatment without the use of progesterone devices to more traditional protocols. Forty Sarda sheep were divided into 2 groups: without sponges (WS) (n = 20) and with sponges (S) containing 40mg FGA for 12 d (n = 20) (control group); 350 I.U. of porcine FSH per sheep was administered in eight decreasing doses twice daily starting four days after estrus was detected (Day 0) in group WS and 48 h before sponge removal in group S. A single i.m. dose of 125 μg of cloprostenol was administered on Day 6 after estrus in group WS to induce luteolysis. Sheep were naturally mated 24 h after cloprostenol injection or sponge removal. Seven days after mating, an inguinal laparotomy was performed and the number of corpora lutea (CL) recorded. Embryos were recovered surgically by flushing each uterine horn. A total of 38 fresh and 22 vitrified embryos were transferred in pairs into 3 groups of recipients seven days after estrus detection: fresh embryos from group S (S-F) (n = 9), fresh embryos from group WS (WS-F) (n = 10) and vitrified embryos from group WS (WS-V) (n = 11). Data on the number of corpora lutea (CL), recovered ova and embryos (OER), and quality 1-2 and 3 embryos (EQ_1-2, EQ₃) per ewe were analyzed by ANOVA. Recovery (RR), fertility (FR) and quality 1-2 embryo (Q_1-2R) rates per treatment were analyzed by a Chi Square analysis. A Chi Square analysis was also applied to pregnancy rate (PR), lambing rate (LR) and twinning rate (TR) of fresh and vitrified embryos in order to analyze embryo transfer results. Among all superovulation variables analysed, results show statistically significant differences in mean number of CL/ ewe (9.3 ± 3.9 vs 7 ± 3.2), RR (67% vs 80 %) and FR (100% vs 80%) (P < 0.05) between WS and S groups respectively. There were no significant differences in PR (78%, 70% and 82%), LR (67%, 60% and 59%) and TR (71%, 71% and 44.4%) among S-F, WS-F and WS-V groups respectively. In conclusion, it is possible to produce a good number of transferable embryos during natural oestrus avoiding the use of sponges.     

Effect of dexamethasone and hydrocortisone on the course of superovulation in cattle

The effect of hydrocortisone and dexamethasone on superovulation was examined in 12 cows. On the day PMSG was given, each animal received either the first of five daily doses of 250 mg succinate hydrocortisone or one injection of 30 mg dexamethasone. In the 48-hr interval between the injection of PMSG and PGF(2)alpha, the concentration of progesterone rose from 6.97 to 10.22 ng/ml in the experimental groups and only to about 2.8 ng/ml in the control group. In the following days progesterone increased even more, from 15.7 to 26.0 ng/ml seven days after estrus in the experimental group and to 19.25 ng/ml in the control group. The group which received dexamethasone had an average of 4.7 corpora lutea and one embryo flushed per animal. The hydrocortisone group had an average of 2.5 corpora lutea and one cow had two embryos. The control group had 6.2 corpora lutea and 5.2 embryos per animal.     

Recovery rate and quality of embryos collected from suckled cows and beef heifers after superovulation with PMSG

Recovery rate and embryo quality were investigated in beef heifers and suckled cows following superovulation induced by 2000 IU pregnant mare serum (PMSG) combined with different methods of estrus cycle synchronization (Norgestomet, Prid, Dinolytic, Norgestomet combined with Dinolytic). Genital tracts were flushed upon slaughter with Dulbecco's medium 6.5 to 7.5 days after insemination. Of the heifers, 42 out of 43 responded to treatment. The mean embryo recovery rate, based on the number of corpora lutea, was only 14.8%. Of the 83 embryos recovered, 54.2% had developed to the expected stage and only 40% appeared normal. Of the adult cows, 55 out 58 responded with an embryo recovery rate of 39.5%. Of the 149 embryos recovered, 48.9% had developed to the expected stage and 67.1% of these appeared normal. In both heifers and adult cows, the different methods of estrus synchronization produced no significant differences in recovery rate or embryo quality.     

Embryo Transplantation in Cattle

Fourteen true repeat breeders with entirely normal oestrous cyclicity more than 1 year after calving and 14 control donor cows were superovulated with PMSG (2000 i.u.) and flushed non-surgically 6–8 days after the superovulatory heat. The superovulatory response was identical for the 2 groups such as assessed by the number of corpora lutea (9.4 ± 1.8 C.L. per repeat breeder and 9.1 ± 1.5 per control cow), occurrence of ovarian overstimulation (polycysts), presence of a non-countable amount of corpora lutea, negative outcome of the flushings and the number of recovered embryos (5.8 ± 1.0 embryos per repeat breeder and 6.0 ± 1.8 embryos per control cow). The most pronounced difference between the 2 categories of animals was related to the fertilization rate of embryos. In the repeat breeder group only 2.4 embryos per cow or 41 % were fertilized, whereas the control animals attained a fertilization rate of 4.9 embryos or 82 %. Since most factors liable to interfere with the fertilization process were identical for both groups (age, breed, nutritional and management conditions, semen quality, dose, AI-technician e.g.), it is believed that intraovarian, follicular, or follicular-dynamic conditions were responsible for producing a high proportion of non-fertilizable oocytes.     

Preovulatory LH profiles of superovulated cows and progesterone concentrations at embryo recovery

Forty-two Holstein cows were randomly assigned to three superovulatory treatment groups of 14 cows each. Cows in Group I received follicle stimulating hormone (FSH; 50 mg i.m.); those in Group II received FSH (50. mg i.m.) along with GnRH (250 ug in 2 % carboxymethylcellulose s.c.) on the day of estrus; and cows in Group III were infused FSH (49 mg) via osmotic pump implants. FSH was administered over a 5-d period for cows in Groups I and II (twice daily in declining doses). Cows in Group III received FSH over a 7-d period (constantly at a rate of 7 mg/day). All cows received 25 mg PGF(2)alpha (prostaglandin F(2)alpha) 48 hours after initiation of the FSH treatment. Blood samples were collected from seven cows from each group at 2 hour intervals on the fifth day of superovulation for serum luteinizing hormone (LH) concentration analysis by radioimmunoassay, and blood samples were collected from all cows on the day of embryo recovery for plasma progesterone determination. The LH profile was not altered (P>0.05) by either GnRH administration or by the constant infusion of FSH as compared to FSH treatment alone. Plasma progesterone concentrations were highly correlated with the number of corpora lutea (CL) palpated (r=0.92; P<0.01) and with the number of ova and/or embryos recovered (r=0.88; P<0.01). The accuracy of predicting the number of recoverable ova and/or embryos by the concentration of plasma progesterone was 86%.     

Superovulation and recovery of zygotes suitable for microinjection in different breeds of sheep

This study investigated the appropriateness of different superovulatory protocols in various breeds of sheep for obtaining a maximum of zygotes suitable for microinjection. Animals were mated either once or two to three times to fertile rams. In Experiment 1, a 24 h interval between a two to three times mating and egg recovery resulted in 42.2% suitable zygotes whereas with single mating only 10.4% fertilized eggs were obtained. The extension of the interval to 40 h associated with a two to three times mating resulted in a recovery of 42.9% fertilized eggs but most (70%) of these were already at the two-cell stage. In Experiment 2, eCG resulted in similar superovulatory responses in Merino ewes as the more labour requiring FSH treatment (8.1 ± 4.5 versus 7.5 ± 4.1 corpora lutea (CL); 6.3 ± 3.0 versus 6.8 ± 4.0 oocytes/ zygotes; 39.4% versus 40.6% fertilization rate). In Experiment 3, following superovulation with pFSH (Folltropin®) the number of CL was not different among Merino, Finn, Crossbreds (Blackface X Finn) and Texel sheep (8.6 ± 5.2; 10.3 ± 4.5; 8.5 ± 3.8; 8.2 ± 2.8, respectively) as was the number of recovered oocytes/ zygotes (7.4 ± 5.6; 9.8 ± 4.3; 7.3 ± 3.8; 6.4 ± 2.9, respectively). However, the number of unfertilized ova was higher (P < 0.05) in Finn sheep as compared with Crossbreds and Texel sheep (5.0 ± 3.3 versus 2.2 ± 2.3 and 1.9 ± 2.6). Similarly, the fertilization rate was higher (P < 0.05) in Crossbreds and Texel sheep (64.4% and 65.5%) as compared with Finn and Merino sheep (38.3% and 42.5%). In Experiment 4, it was shown that in Merino sheep purified FSH supplemented with 68.6% LH resulted in lower (P < 0.05) superovulatory responses as compared with purified FSH supplemented with 133.1% LH or Folltropin (LH contamination 0.1%) (4.7 ± 3.3 versus 8.8 ± 3.8 and 8.6 ± 5.2 CL; 3.8 ± 2.5 versus 7.4 ± 3.6 and 7.4 ± 5.6 oocytes/zygotes, respectively). A three times repeated superovulatory treatment and oviductal flush per animal at monthly intervals did reduce (P < 0.05) the number of CL, but had no deleterious effect on zygote yields and the percentage of microinjectable zygotes. We conclude that (1) at least a two to three times mating is required to obtain acceptable fertilization rates; (2) the interval between mating and recovery should be 24–26 h in order to obtain zygotes; (3) eCG results in similar superovulatory responses as FSH; (4) Folltropin® is a suitable drug to induce superovulation in sheep; (5) the LH content of the FSH preparation plays a significant role in the superovulatory response of sheep; (6) superovulation and embryo recoveries can be repeated at least three times per animal without decrease in efficiency.     

Efficiency of pituitary extracts (FSH) for induction of superovulation in cattle

In four experiments on 195 adult cows the number of corpora lutea, as determined by rectal palpation, and the number and quality of embryos, as determined after non-surgical recovery, were studied following 4 days of treatment with superovulatory doses of follicle stimulating hormone. Neither the total dose, the commercial origin of the hormone preparation, nor the volume of saline used as an injection medium had a significant effect on the responses. However, the number of injections per day and the pattern of doses within the injection regime were found to exert significant effects. The greatest response (15.9 ± 15.0 corpora lutea, 12.2 ± 12.3 embryos recovered and 5.3 ± 6.2 transferable embryos) was observed after the administration of the hormone twice a day at decreasing doses.     

Calves born from anestrus yaks (Poephagus grunniens L.) subjected to Ovsynch and superovulation treatment

An attempt was made to induce estrus and ovulation in eight anestrus yaks by use of the Ovsynch protocol. Six out of eight yaks were successfully induced into estrus, and ovulation occurred in all the responding yaks 1-2 days after the second GnRH administration. Out of the six animals that responded to the treatment, two mated naturally with yak bulls, and calves were obtained from them. The other four animals were further administered a superovulatory regimen of Folltropin (FSH-P). Following Folltropin and Ilerin (a PGF(2alpha) analog) treatment, the animals were subjected to natural insemination. Only one animal in which natural mating occurred was flushed non-surgically for embryo recovery 7 days post-insemination. Thereafter, all the donor animals were administered with Ilerin. After 48-72 h, they came into heat and mated naturally with yak bulls, and calves were obtained from them after expiration of the normal gestation period. Following superovulation, the average numbers of palpable corpora lutea in the right and left ovaries were 2.25+/-0.6 and 1.75 +/-0.3, respectively. Three embryos were recovered by non-surgical flushing from a single animal. One embryo was transferred to a recipient yak, who produced one female calf after 258 days. This is the first report of production of a yak calf through embryo transfer-technology.     

Fertilization and embryo recovery rates in superovulated chios ewes after laparoscopic intrauterine insemination.

Forty superovulated dairy ewes of the Greek Chios breed were used in an experiment to evaluate the efficiency of laparoscopic intrauterine insemination on fertilization and embryo recovery rates as well as embryo quality. Estrus was synchronized by intravaginal progestagen impregnated sponges and superovulation was induced by administration of 8.8 mg o-FSH i.m. following a standard 8 dose protocol. A small volume (0.3 mL) of diluted fresh ram semen was deposited in each uterine horn 24 to 28 h after onset of the estrus by a laparoscopic technique. The animals were allocated randomly into two groups (Group A and B) of 20 animals each. In Group A, embryos were recovered 18 to 24 h after the intrauterine insemination and in Group B on Day 6. The average number of corpora lutea was 12.8 +/- 1.2 and 11.5 +/- 1.1 (+/- SEM); the overall embryo recovery was 66.4% and 57% and the percentage of recovered fertilized ova was 81% and 82.8% in Groups A and B, respectively. More fertilized ova were collected per ewe from Group A (P < or = 0.1). Results indicated that in Chios breed, superovulation using homologous FSH combined with laparoscopic AI leads to good ovarian response with satisfactory results in fertilization, embryo recovery and quality of embryos. This could lead to improved and more efficient methods for obtaining large numbers of high quality oocytes and embryos for embryo transfer programs which could contribute to genetic improvement and increase of the population size.     

Association between numbers of ovarian follicles in the first follicle wave and superovulatory response in ewes

The aim of this study was to examine the variability in the number of ovarian follicles in sheep and to determine if the average number of follicles per day influences the response to superovulation and resulting embryo quality. Ewes (n = 83) were synchronized and the number of follicles (≥2 mm diameter) in the ovaries were counted daily between Days 0 and 4 of the oestrous cycle using transrectal ultrasonography. Fourteen to 21 days later, 47 ewes were randomly chosen from the group and were treated with an intravaginal progestagen pessary for 12 days and superovulated with 1500 IU eCG administered as a single injection 10 days after sponge insertion. Ewes were mated and reproductive tracts were recovered after slaughter on Day 6 of pregnancy. The number of corpora lutea was counted, uterine horns were flushed and the morphology and developmental stage of the recovered oocytes/embryos was assessed. The mean daily number (±S.D.) (≥2 mm diameter) of follicles per ewe was 8.5 ± 2.8 (ranging between 3 and 16). After superovulation animals with few follicles (Low group: <8 follicles/day; n = 21) had fewer (P < 0.005) corpora lutea, total structures (unfertilized oocytes and embryos), good quality and total embryos compared to animals with many follicles (High group: ≥8 follicles/day; n = 23). No difference was found in the proportion of good quality embryos (relative to the total number; Low 0.68 ± 0.11 versus High 0.79 ± 0.08; P = 0.21) between the two groups, or the recovery rate, the number of unfertilized oocytes or the number of poor quality embryos per animal. We conclude that ewes with a higher number of follicles (≥8) during the first follicular wave had a better superovulatory response (in terms of corpora lutea and high quality embryos) 2–3 weeks later; however, there was no relationship between the number of follicles and the proportion of good quality embryos per animal.     

Embryo transfer in fertile and infertile cows

Pregnancy rates were compared between fertile and infertile donors in an embryo transfer program. Non-surgical embryo transfer techniques were utilized for examination of uterine contents and collection of ova. Recovered embryos were transferred surgically into suitable recipients. Three groups of donors were included in this investigation: a) fertile; b) infertile, due to known causes (diagnosed); c) infertile, due to unknown causes (undiagnosed). There were 11.3, 6.6 and 8.0 corpora lutea; 6.8, 1.2 and 1.0 fertilized ova; 3.6, 0.8 and 0.4 pregnancies per superovulation for the fertile, diagnosed and undiagnosed groups, respectively. In 23 months, unsuperovulated, fertile, diagnosed and undiagnosed donors yielded 17, 15 and 9 fertilized ova which resulted in 15, 13, and 3 pregnancies, respectively. Donors treated for uterine infections, adhesions or cystic ovaries prior to superovulation responded with 10.1, 7.6 and 4.1 corpora lutea; 1.9, 4.0 and 0.3 fertilized ova; 1.1, 3.3 and 0.2 pregnancies per superovulation, respectively. Relatively few viable embryos were recovered from donors with chronic cystic ovaries or from infertile cows of unknown etiology. Infertile donors, when compared to fertile donors, were unproductive when used for embryo transfer.     

Survival of ovine embryos stored at 4 degrees C for 24 hours

This study was conducted to ascertain if sheep embryos collected for transfer can be stored for short periods without freezing to allow for international transport. Of twelve Finnish Landrace ewes treated with equine follicle stimulating hormone (FSH), eleven ewes ovulated with a mean of 9.1 +/- 4.3 (SD) corpora lutea. Recovery rate from the nine ewes with normal corpora lutea was 68 +/- 27%, providing 61 morulae which were then cooled to 4 C and stored for 24 h while transporting them from Scotland to France. Romanov recipients received either 4 (n = 14) or 5 (n = 1) of these morulae. Fourteen of the recipients lambed, with a mean lambing rate of 2.1 +/- 0.8, representing 48.3% of embryos transferred. Cooling of embryos to 4 C and storing them in ovum culture medium for 24 h at 4 C may be a valuable technique for the handling and short-term storage of embryos.