Use Of Embryo Transfer Research Articles

Birth of first twin calves produced by intrafollicular transfer of immature oocyte

AbstractIn an adequate system of nutrition and management, the birth of twin calves can increase the productive efficiency in beef cattle. In this sense, genetic selection, hormonal treatment and the use of embryo transfer are strategies to produce twins in cattle. In the present report, we describe an alternative method for the production of twins based on the intrafollicular transfer of immature oocytes that resulted in the birth of the first twins reported using this technique. The expectation is to significantly improve the performance of the technique in the near future, making it another reproductive tool to be applied in the production and research sectors.

ET/advanced repro technologies and synchronization

Embryo transfer in cattle can be extremely rewarding for both the cattle producer and veterinarian. A conventional flush can be achieved through a serious of shots to a donor cow, which can be stimulated to produce more offspring than she normally would in her lifetime. The process of a conventional flush will be discussed as well as grading and evaluating embryos. In ad­dition to domestic use of embryo transfer, the International Embryo Technology Society (IETS) has a set of guidelines that allows veterinarians to follow to collect and freeze embryos for exportation either through in-vivo or in-vitro production. The process of in-vitro produced (IVP) embryos will be briefly dis­cussed along with various synchronization protocols for both production systems.

Economic analysis of the use of in vitro produced embryos transferred during heat stress under dairy herd constraints

The use of embryo transfer helps to improve reproductive performance during periods of heat stress. In vitro produced embryo transfer (IVP-ET) is more expensive than artificial insemination. We hypothesized that the value IVP-ET in seasonal herds depends on herd constraints, such as the maximum number of milking cows and the maximum number of calvings that can be accommodated throughout the year. Therefore, the objective of this study was to estimate how profitability in dairy herds exposed to summer heat stress is affected by the number of months in which IVP-ET is used, the use of IVP-ET in repeat-breeder cows, IVP-ET cost, and herd constraints. We built and used a nonlinear programming model of a dairy herd with young stock and cows with monthly Markov Chain transitions. The model varied the number of heifers calving in each calendar month to maximize herd profitability. We varied IVP-ET cost ($100 or $200), duration of the IVP-ET program (2 or 4 months), and the breeding number in which IVP-ET started (1st or 3rd). In total, 20 scenarios were simulated. Maximum profitability was obtained when IVP-ET was not used, regardless of herd constraints. The 16 scenarios in which IVP-ET was used showed increased seasonality in milk yield, numbers of milking cows, total cows, total calvings, and heifer calvings because the program tried to limit the number of IVP-ET breedings in the summer. The addition of the calving constraint increased the value of IVP-ET. The breakeven cost per IVP-ET ranged from −$6.79 to $24.38 compared with conventional semen cost of $20. In conclusion, the current market costs of IVP-ET did not warrant application with the objective to increase reproductive performance during heat stress. Herd constraints on the maximum allowable seasonality in the monthly number of milking cows and calvings affected the value of IVP-ET during heat stress.

Clinical efficacy of hyaluronate-containing embryo transfer medium in IVF/ICSI treatment cycles: a cohort study.

STUDY QUESTIONDoes the duration of embryo exposure to hyaluronic acid (HA) enriched medium improve the rate of live birth events (LBEs)?SUMMARY ANSWERThe use of embryo transfer (ET) medium rich in HA improves LBE (a singleton or twin live birth) regardless of the duration of exposure evaluated in this study, but does not alter gestation or birthweight (BW).WHAT IS KNOWN ALREADYHA-enriched medium is routinely used for ET in ART to facilitate implantation, despite inconclusive evidence on safety and efficacy.STUDY DESIGN, SIZE, DURATIONA cohort study was performed evaluating clinical treatment outcomes before and after HA-enriched ET medium was introduced into routine clinical practice. In total, 3391 fresh ET procedures were performed using low HA and HA-rich medium in women undergoing publicly funded IVF/ICSI treatment cycles between May 2011 and April 2015 were included in this cohort study.PARTICIPANTS/MATERIALS, SETTING, METHODSA total of 1018 ET performed using low HA medium were compared with 1198, and 1175 ET following exposure to HA-rich medium for 2–4 h (long HA exposure) or for 10–30 min (short HA exposure), respectively. A multiple logistic regression analysis was used to compare clinical outcomes including BW, gestational age and sex ratios between groups, whilst adjusting for patient age, previous attempt, incubator type and the number of embryos transferred.MAIN RESULTS AND THE ROLE OF CHANCEThe use of HA-rich medium for ET was positively and significantly associated with improved clinical pregnancy rate and LBE, for both exposure durations: long HA (odds ratio (OR) = 1.21, 95% CI: 0.99–1.48), short HA (OR = 1.32, 95% CI: 1.02–1.72) and pooled OR = 1.26, 95% CI: 1.03–1.54, relative to the use of low HA medium. A comparative analysis of the risks of early pregnancy loss following long HA exposure (OR = 0.76, 95% CI: 0.54–1.06), short HA exposure (OR = 0.84, 95% CI: 0.54–1.30) and late miscarriage (OR = 0.88, 95% CI: 0.51–1.53) (OR = 1.41, 95% CI 0.72–2.77), were lower and not statistically significant. Similarly, ordinary regression analysis of the differences in BW at both HA exposures; pooled OR = −0.9 (−117.1 to 115.3), and adjusted BW between both HA cohorts; pooled OR = −13.8 (−106.1 to 78.6) did not show any differences. However, a difference in gestational age (pooled OR −0.3 (−3.4 to 2.9)) and sex ratio (pooled OR 1.43 (0.95–2.15)) were observed but these were not statistically significant relative to low HA medium.LIMITATIONS, REASONS FOR CAUTIONThe strength of a randomized treatment allocation was not available in this evaluation study, therefore effects of unmeasured or unknown confounding variables cannot be ruled out.WIDER IMPLICATIONS OF THE FINDINGSThe result of this large cohort study strengthens the case for using HA-rich medium routinely at transfer, while adding the important clinical information that duration of exposure may not be critical. The composition and effects of commercial IVF culture media on success rate and safety remains a major controversy despite increasing calls for transparency and evidence-based practice in ART. Nonetheless, the lack of differences in BW and gestational age observed in this study were reassuring. However, an appraisal of clinical outcomes and appropriate research investigations are required for the continuous evaluation of efficacy and safety of HA.STUDY FUNDING/COMPETING INTEREST(S)T.A. is funded by a Clinical Doctoral Research Fellowship (CDRF) grant (reference: ICA-CDRF-2015-01-068) from the National Institute for Health Research (NIHR). The views expressed in this publication are those of the authors and not necessarily those of the NHS, the National Institute for Health Research or the Department of Health. The authors declare no conflict of interest.

Possibilities for a specific breeding program for organic dairy production

Organic dairy production differs from conventional dairy production in many aspects. However, breeding programs for the 2 production systems are the same in most countries. Breeding goals (BG) might be different for the 2 production systems and genotype × environment interaction may exist between organic and conventional dairy production, both of which have an effect on genetic gain in different breeding strategies. Other aspects also need to be considered, such as the application of multiple ovulation and embryo transfer (MOET), which is not allowed in organic dairy production. The general aim of this research was to assess different environment-specific breeding strategies for organic dairy production. The specific aim was to study differences in BG weights and include the effect of genotype × environment interaction, MOET, and the selection of breeding bulls from the conventional environment. Different scenarios were simulated. In the current scenario, the present-day situation for dairy production in Denmark was emulated as much as possible. The BG was based on a conventional dairy production system, MOET was applied in both environments, and conventional bulls could be selected as breeding bulls in the organic environment. Four alternative scenarios were simulated, all with a specific organic BG in the organic breeding program but differences in the usage of MOET and the selection of conventional bulls as breeding bulls. Implementation of a specific BG in organic dairy production slightly increased genetic gain in the aggregate genotype compared with the breeding program that is currently implemented in organic dairy production. Not using embryo transfer or only selecting breeding bulls from the organic environment decreased genetic gain in the aggregate genotype by as much as 24%. However, the use of embryo transfer is debatable because this is not allowed according to current regulations for organic dairy production. Assessing genetic gain on trait levels showed that a significant increase for functional traits was possible compared with the current breeding program in the organic environment without a decrease in genetic gain in the aggregate genotype. This difference on trait level was even more present when selection of conventional bulls as breeding bulls in the organic environment was not possible. This finding is very relevant when breeding for the desired cow in organic dairy production.

Historical Aspects of Equine Embryo Transfer

Early embryo transfer in equids was undertaken simultaneously in the early 1970s in Cambridge, England, and Kyoto, Japan. Both groups achieved limited success when flushing the uterine horn ipsilateral to the side of ovulation but the rates improved markedly when the whole uterus was flushed on realization of the continued movement of the embryo throughout the uterine lumen after day 6. Initial transfers of embryos to recipient mares were carried out surgically, but nonsurgical transfer via the cervix has been used subsequently with increasing success, culminating in pregnancy rates of 75%–90% today. Experimental use of embryo transfer in horses and donkeys demonstrated the unique ability of equids to carry to term a full range of interspecies hybrid conceptuses and extraspecies pregnancies created by embryo transfer. Furthermore, splitting of day 4–8 cell embryos and day 6 compact morulae allowed the creation of genetically identical twin foals. But despite these and other significant advances over the past 45 years, a persisting limitation is the relatively low embryo recovery rates from donor mares treated with exogenous gonadotropins in attempts to induce them to superovulate. This is due to the toughness of the ovarian tunica albuginea which forces ovulation through the ventrally situated ovulation fossa where multiple follicles compete with each other and luteinize before they can ovulate properly.

The main challenges facing camel reproduction research in the 21st century

The reproductive efficiency of camels under their natural pastoral conditions is low. The reasons for this low reproductive efficiency include the short breeding season, the late age of reaching puberty and the long gestation period of 13 months. The introduction of controlled breeding programmes is important but several problems have to be considered. For example, oestrous behaviour is very vague and difficult to interpret, as it does not often relate to follicular development in the ovaries. In addition, all camelids are induced ovulators that normally ovulate only in response to mating, so alternative methods of inducing ovulation, such as injecting gonadotrophic hormones, have been investigated. The use of embryo transfer is becoming increasingly important but involves the necessity to superovulate the donors and synchronize the recipients so that they ovulate preferably 24 h after the donor. Superovulation can be achieved using exogenous gonadotrophins, although there is a high incidence of follicle luteinization before mating, of overstimulated ovaries and non-responsive females. The development of AI in camels is complicated by the difficulty of collecting semen and the gelatinous nature of the semen produced. However, diluting semen in Green Buffer and inseminating a minimum of 300 x 10(6) live spermatozoa has given encouraging results. The ability to control the follicular cycle of camels is leading to an improvement in reproductive efficiency.

191 The effect of high and low doses of follicle-stimulating hormone on embryo collection in Romanov sheep

The use of embryo transfer in small ruminants has served as a way of increasing superior female genetics. This technique, although not new, has been adopted by an increasing number of breeders over the past few years. The Romanov sheep breed is considered a natural litter-bearing breed compared with other small ruminant species, which generally have only 1 or 2 offspring during a natural parturition. This experiment was designed to evaluate the effect of FSH dosage on embryo production and collection in Romanov sheep. Sheep donors (n=12), with an average age of 2±1.4 years and an average body weight of 43±6.7kg, were randomly assigned to either a high (175mg) or low (140mg) dosage treatment of FSH during the breeding season. Hormone injections were given in a decreasing dosage twice daily over a period of 5 days. Donors were naturally cycling before being subjected to a CIDR-G protocol for a period of 15 days, with hormone injections beginning on Day 11. Donors were mated with rams (n=2) of known fertility for a total of 3 hand matings. After the third hand mating, the ram was turned into the breeding pen with the ewes. Embryos were collected 7 days after breeding and evaluated for transfer. A one-way ANOVA was utilised to analyse statistical differences between groups with significance set at (0.05). Results are given as mean±s.e.m. Only embryos of quality grades 1 and 2 were transferred during this study. No differences were detected between the 2 groups for total embryos collected between both high (7.6±6) and low (6.6±5) FSH groups. Furthermore, no differences were detected between both high and low FSH groups for the number of embryos transferred (5.6±5 and 6.3±4, respectively). The results of this study suggest that a lower total dosage (140mg) of FSH can be used in superovulation programs of Romanov ewes without affecting the total number of embryos collected and transferred. However, further investigation should be performed with various levels of FSH to determine the most accurate dosage for Romanov sheep.

Factors in cattle affecting embryo transfer pregnancies in recipient animals

The use of embryo transfer (ET) in cattle is important for profitability and improved genetic gains. The advent of the commercial embryo collection and transfer industry has led to advancements in multiple techniques and practices. Specific variables, however, have historically affected pregnancy rates but an understanding of the magnitude of these effects in the current industry is limited. Transfer location (cranial, middle, or caudal third of the uterine horn ipsilateral to the ovary with a CL), transfer score (range of 1–3 with 1 being excellent and 3 poor, based on difficulty of accessing the site of embryo deposition), and amount of time to complete a transfer, therefore, were recorded. These variables were collected in a setting designed to mimic commercial production practices as well as exaggerated time (due to data collection) to assess effects on pregnancy rates. Fresh and frozen in vivo-derived embryos (n = 256) from Bos taurus cows were transferred to Bos taurus recipients. There tended to be more pregnancies when embryos were deposited in the cranial part of the uterus (P = 0.08) compared to the middle and caudal third of the uterus. With a lesser degree of difficulty in transfers (score 1), there tended to be more pregnancies established (P = 0.07). When lesser time was needed for transferring embryos and collecting data, there were greater pregnancy rates (P = 0.03). Thus, these traditionally accepted variables of influence (site of embryo placement in uterus, difficulty, and time) continue to influence ET pregnancy success.

Cryosurvival and pregnancy rates: One-step protocol for freezing-thawing Shangri-la Yak (Bos grunniens) Embryos.

The yak is one of the most important and economically useful animals for highlanders. The decline in the yak population requires effective measures for the conservation and multiplication of elite germplasm. A standardized protocol will simplify the freezing and warming of yak embryos in straw and facilitate embryo transfer. In this work, we investigated a one-step protocol that uses a stable basal medium, which comprised a warming medium (1.08M sucrose) and a freezing medium (EFS40). We also assessed the effects of the new transfer method on embryo survival. A total of 145 yak frozen embryos were thawed in a standard medium system. The one-step protocol led to a high recovery percentage (84.93) of yak embryos that survived vitrification and warming. The in vitro survival rates of these embryos significantly different from those of embryos frozen-thawed via the conventional method. The 95 embryos frozen-thawed via our one-step protocol were then implanted in selected recipients. Thirty-six singleton pregnancies were established. In conclusion, the proposed one-step method is a simple, safe, and standardized freezing-thawing protocol that ensures embryo survival and quality under field conditions. This study establishes new possibilities for the widespread use of embryo transfer in yaks.

Fibroblast Growth Factor 10 Enhances the Developmental Efficiency of Somatic Cell Nuclear Transfer Embryos by Accelerating the Kinetics of Cleavage During In Vitro Maturation.

Somatic cell nuclear transfer (SCNT) is required for the generation of transgenic animals as disease models. During the in vitro development of SCNT embryos, the quality of matured oocytes is one of the major factors regulating the developmental potential of embryos. Time-lapse monitoring systems are new tools that assess the developmental capacity of embryos for use in embryo transfer. In this study, we investigated the effect of fibroblast growth factor 10 (FGF 10) on the developmental potential of SCNT embryos. After the in vitro maturation (IVM) of oocytes in IVM medium containing 10 ng/mL FGF 10 (10 F), the polar body extrusion rate was significantly higher than in the control. However, there was no difference in the percentage of fused embryos between the groups. The cleavage and blastocyst formation rates of embryos were significantly increased in the 10 F compared with the control. In addition, the total cell number was higher and the apoptotic index was lower in the 10 F than control at day 7. The messenger RNA (mRNA) expression of genes involved in apoptosis (baculoviral inhibitor of apoptosis repeat containing 5 [BIRC5] and caspase 3 [CASP3]) and development (octamer-binding transcription factor 4 [POU5F1] and sex determining region Y box 2 [SOX2]) increased after 10 F treatment. Furthermore, the kinetics of the first cleavage was faster and the percentage of embryos at cell block was significantly lower in the 10 F group than in the control. These results demonstrate that exposure of oocytes to FGF 10 during IVM promotes developmental competence.

Mutation of the Sp1 binding site in the 5' flanking region of SRY causes sex reversal in rabbits.

Sex-determining region Y is a crucial gene that initiates male sex determination in mammals. Mutations of the Sp1-binding site in the 5′ flanking region of SRY are associated with clinical male-to-female sex reversal syndrome, although such occurrences are rare and, until now, have not been reported in animal models. In this study, we mutated Sp1-binding sites in the 5′ flanking region of the rabbit SRY gene using the CRISPR/Cas9 system. As expected, the SRY-Sp1 knockout rabbits had female external and internal genitalia and exhibited normal female copulatory behaviors, but they were infertile, and the adults displayed reduced follicles. Interestingly, we successfully obtained offspring from sex-reversed SRY-Sp1 knockout rabbits using embryo transfer. In summary, our study demonstrates that Sp1 is a major regulator in SRY gene transcription, and mutations of the Sp1 binding sites (Sp1-B and Sp1-C) in the 5′ flanking region of SRY induce sex reversal in rabbits, which can be used as targets for clinical research of male-to-female sex reversal syndrome. Additionally, we provide the first evidence that sex reversal syndrome patients have the potential to become pregnant with the use of embryo transfer.

Effective vitrification and warming of porcine embryos using a pH-stable, chemically defined medium.

The use of pH-stable media would simplify embryo vitrification and the warming of porcine embryos and might facilitate the application of embryo transfer in practice. In this work, we investigated whether a pH-stable basal medium constituted of Tyrode’s lactate medium, polyvinyl alcohol, and HEPES for buffering was suitable for porcine embryo vitrification warming in place of the conventional gas-equilibrated media. A high percentage (>90%) of embryos survived vitrification and warming in this medium, achieving in vitro survival rates similar to embryos vitrified-warmed using the conventional protocol and their fresh counterparts. The pH-stable medium did not affect the in vivo developmental competence of the vitrified-warmed embryos. A farrowing rate of 71.4% (5/7) with 10.4 ± 3.1 piglets born was obtained for the embryos vitrified and warmed in this medium and transferred to selected recipients. This medium will enable the use of simple, safe and standardized protocols for the vitrification and warming of porcine embryos for optimal embryo survival and quality when applied under field conditions. This study opens new possibilities for the widespread use of embryo transfer in pigs.

Developmental potential of oocytes with smooth endoplasmic reticulum clusters and their behaviors observed by time-lapse recording system

We previously reported that oocyte morphology was associated with embryo quality and viability, suggesting that controlled assessment of oocyte morphology is useful to predict human embryo quality.During intracytoplasmic sperm injection (ICSI), we occasionally observe oocytes with smooth endoplasmic reticulum clusters (sERC) (Otsuki et al, 2004), which are thought to disappear after fertilization and be closely associated with poor prognosis in achieving pregnancy. This study aimed to investigate the developmental potential of oocytes with sERC and their behaviors using time-lapse recording system. Research study We collected the data of 6,765 matured oocytes retrieved after controlled ovarian hyper-stimulation from August 2010 to September 2015. During ICSI, three experienced embryologists noticed oocytes containing vacuole-like structures, which were defined as sERC by their disappearance at the zygote stage. These embryos were incubated and imaged by either high-resolution time-lapse cinematography or EmbryoScope®. Developmental velocity, rate of clinical use in embryo transfer or cryopreservation, and achieving pregnancy were compared between oocytes with [sERC(+)] and without sERC [sERC(-)]. Of the 6,765 mature oocytes, 46 (0.7%) showed sERC(+). The developmental velocity of embryos derived from sERC(+) oocytes was significantly higher than that of sERC(-) oocytes, including the time of 2nd polar body (PB) extrusion, pronuclei (PN) formation, and syngamy from the ICSI procedure (in h: 2.5±0.6 vs. 2.9±1.0, 7.6±2.4 vs. 9.9±3.9, and 20.7±2.2 vs. 23.7±4.5, respectively; P<0.05). The sERC all disappeared by 4.3±1.2 h after ICSI in the period from 2nd PB extrusion to PN formation. The rate of clinical use of sERC(+) oocytes was 80.4% (37/46), of which 6 underwent fresh embryo transfer and 31 were cryopreserved. In total, 15 embryos were transferred (6 fresh embryos, 9 frozen/thawed embryos), the pregnancy rate was 40% (6/15), and miscarriage rate was 33.3% (2/6). Moreover, the live birth rate was 50.0% (3/6) and one is still ongoing. Healthy babies were born from oocytes with sERC(+). This study demonstrated that oocytes with sERC could develop into good quality embryos and achieve successful pregnancy resulting in healthy babies. Further follow-up of the children are clearly needed, and mechanisms of the emergence of sERC and its impact on embryonic development are still under investigation. Detailed studies with molecular biological methods are necessary.

Successful non-surgical deep uterine transfer of porcine morulae after 24 hour culture in a chemically defined medium.

Excellent fertility and prolificacy have been reported after non-surgical deep uterine transfers of fresh in vivo-derived porcine embryos. Unfortunately, when this technology is used with vitrified embryos, the reproductive performance of recipients is low. For this reason and because the embryos must be stored until they are transferred to the recipient farms, we evaluated the potential application of non-surgical deep uterine transfers with in vivo-derived morulae cultured for 24 h in liquid stage. In Experiment 1, two temperatures (25°C and 37°C) and two media (one fully defined and one semi-defined) were assessed. Morulae cultured in culture medium supplemented with bovine serum albumin and fetal calf serum at 38.5°C in 5% CO2 in air were used as controls. Irrespective of medium, the embryo viability after 24 h of culture was negatively affected (P<0.05) at 25°C but not at 37°C compared with the controls. Embryo development was delayed in all experimental groups compared with the control group (P<0.001). Most of the embryos (95.7%) cultured at 37°C achieved the full or expanded blastocyst stage, and unlike the controls, none of them hatched at the end of culture. In Experiment 2, 785 morulae were cultured in the defined medium at 37°C for 24 h, and the resulting blastocysts were transferred to the recipients (n = 24). Uncultured embryos collected at the blastocyst stage (n = 750) were directly transferred to the recipients and used as controls (n = 25). No differences in farrowing rates (91.7% and 92.0%) or litter sizes (9.0±0.6 and 9.4±0.8) were observed between the groups. This study demonstrated, for the first time, that high reproductive performance can be achieved after non-surgical deep uterine transfers with short-term cultured morulae in a defined medium, which opens new possibilities for the sanitary, safe national and international trade of porcine embryos and the commercial use of embryo transfer in pigs.

Effect of harvesting technique and presence or absence of corpus luteum on in vitro development after parthenogenetic activation of oocytes recovered from buffalo ovaries

Growing human population, increasing urbanization and rising per capital income are predicted to double the demand for the supply of livestock products in developing countries over the next two decades [1]. Livestock production is growing faster than any other sub-sector and it is predicted that by 2020, livestock will produce more than half of the total global agricultural output in terms of value [2]. The buffalo occupies an integral part in the livestock economy of Asia as well as of India and India has highest buffalo population in the world [3]. Buffaloes are major contributors for milk, meat and draught power and the buffalo is considered as the animal of the future in India due to their ability to survive inharshclimaticconditions, in comparison with cattle. However, reproductive efficiency of this species is low and hampered due to delayed puberty, silent estrus, prolonged inter calving intervals, poor conception rates, seasonal anoestrus and poor super ovulatory response [4]. Reproduction lies at the heart of any livestock breeding enterprise and is vital to maintain or increase the number of animals required for production. In order to improve reproductive efficiency of buffalo; assisted reproductive technologies such as artificial insemination (AI), multiple ovulation and embryo transfer (MOET) and production of embryos has been introduced [4]. Progress in the use of embryo transfer in the buffalo is slow due to poor super ovulatory response. embryo production (IVEP) would be an effective technique to improve the efficacy of transferable embryo production [5]. However, embryo production systems in buffalo are still sub optimal when compared with bovine and requires substantial improvement. in vitro

Design, development, and application of a non-surgical deep uterine embryo transfer technique in pigs

There is enormous potential for the use of embryo transfer in pig production because it should make it possible to move genetic material (i.e., embryos) with minimal risk of disease transmission, reduced transportation costs, and no effect on animal welfare during transport. Unlike other livestock, the commercial use of embryo transfer in pigs has been very limited because embryo collection and transfer require surgical procedures. Recently, a new and unique procedure for the non-surgical transfer of porcine embryos deep into a uterine horn of non-sedated gilts and sows has been developed. The excellent reproductive performance of recipients following non-surgical transfer of fresh embryos and the promising results obtained with vitrified embryos represent a fundamental advance in the widespread commercial use of embryo transfer by the pig industry.

Use of assisted reproduction for the improvement of milk production in dairy camels (Camelus dromedarius)

Despite their production potential and ability to survive on marginal resources in extreme conditions, dromedaries have not been exploited as an important food source. Camels have not been specifically selected for milk production, and genetic improvement has been negligible. High individual variation in milk production both within the population and within breeds provides a good base for selection and genetic progress. In this paper, we discuss the possibilities and constraints of selective breeding for milk production in camels, and include a summary of the use of embryo transfer at the world's first camel dairy farm. Embryo transfer is an integral part of the breeding strategy at the camel dairy farm because it increases selection intensity and decreases the generation interval. Using high milk-producing camels as donors and low producing camels as recipients, 146 embryos were recovered (6.1±1.0embryos/donor; range: 0–18). Embryos were transferred non-surgically into 111 recipients (83 single and 28 twin embryo transfers). Pregnancy rate at 21 days and 5 months was 55% (61/111) and 45% (50/111), respectively. Finally, a total of 46 recipients delivered a live calf. These results document the utility of embryo transfer using high milk producing dromedaries as donors.

Use of embryo transfer seven days after artificial insemination or transferring identical demi-embryos to increase twinning in beef cattle1

Our objectives were to determine pregnancy rate, fetal loss, and number of calves born in beef cattle after a fixed-time transfer of an embryo 7 d after a fixed-time artificial insemination (TAI) of cows (Exp. 1) and after transfer of 2 demi-embryos into a single heifer recipient (Exp. 2). In Exp. 1 after synchronization of ovulation, during 2 yr, 297 suckled beef cows were assigned randomly to 1 of 3 treatments: 1) on d 2 cows received a single TAI (TAI-2; n = 99), 2) a fixed-time direct transfer, frozen and thawed embryo placed in the uterine horn ipsilateral to the ovary containing a corpus luteum (CL) on d 9 embryo transfer (ET-9; n = 99), or 3) cows received TAI on d 2 and a frozen and thawed direct transfer embryo placed in the uterine horn ipsilateral to the ovary containing a CL on d 9 (TWIN) treatments (n = 99). Fetal number and viability were determined with ultrasonography at 33 to 35 d and 90 to 100 d after insemination. In Exp. 2, 74 crossbred recipient heifers were assigned randomly to receive either 1) a single whole fresh embryo (WHOLE; n = 37) or 2) 2 identical fresh demi-embryos (SPLIT; n = 37) in the uterine horn ipsilateral to the CL 7 d after an observed estrus. Ultrasonography was used on d 33, 69, and 108 to determine presence and number of embryos or fetuses. Palpation per rectum was used to determine pregnancy status on d 180 of gestation and number of live calves was recorded at birth. In Exp. 1 pregnancy rates on d 30 to 35 were greater (P < 0.05) for TWIN- (48.5%) and TAI-2- (47.5%) than for ET-9- (33.3%) treated cows. Of the 48 pregnant cows in the TWIN treatment, 21 were twin pregnancies whereas there was 1 twin pregnancy in the TAI-2 treatment. As a result, TWIN cows had more fetuses (P < 0.05) as a proportion of all treated cows (69.7%) than TAI-2- (48.5%) or ET-9-(33.3%) treated cows, and cows in the TWIN treatment gave birth to more (P < 0.01) calves (n = 55) compared with cows in the ET treatment (n = 23) whereas cows in the TAI-2 treatment (n = 40) were intermediate. In Exp. 2 heifers receiving SPLIT (81.1%) had greater (P < 0.05) pregnancy rates on d 33 than heifers receiving WHOLE (40.5%). Of the SPLIT heifers that were confirmed pregnant at d 33 after transfer, 57% were gestating twin fetuses. Embryonic or fetal loss from d 33 to birth was greater (P < 0.01) in heifers in the SPLIT treatment (40.0%) compared with the WHOLE treatment (0.0%), but number of calves per female treated was greater (P < 0.05) in heifers in the SPLIT treatment (75.0%) compared with heifers in the WHOLE treatment (40.5%). We conclude that transferring an embryo into a cow 7 d after TAI did not increase the pregnancy rate in Exp.1. However, transferring 2 demi-embryos into a single heifer recipient increased pregnancy rate at 33 d of gestation whereas both methods of inducing twinning resulted in a greater number of calves per female treated. In addition, embryonic or fetal loss associated with unilateral twin pregnancies in heifers occurred at rates greater than those associated with single-fetus pregnancies.

Breeding or Assisted Reproduction? Relevance of the Horse Model Applied to the Conservation of Endangered Equids

Many wild equids are at present endangered in the wild. Concurrently, increased mechanization has pushed back the numbers of some old native horse breeds to levels that are no longer compatible with survival of the breed. Strong concerns arose in the last decade to preserve animal biodiversity, including that of rare horse breeds. Genome Resource Banking refers to the cryostorage of genetic material and is an approach for ex situ conservation, which should be applied in combination with in situ conservation programmes. In this review, we propose that, owing to the great reproductive similarity among the different members of the genus Equus, the domestic horse can be used to optimize cryopreservation and embryo production protocols for future application in wild equids. We will give this hypothesis a scientific underpinning by listing successful applications of epididymal sperm freezing, embryo freezing, intracytoplasmic sperm injection, oocyte vitrification and somatic cell nuclear transfer in domestic horses. Some ART fertilization methods may be performed with semen of very low quality or with oocytes obtained after the death of the mare.