Embryo Transfer Program Research Articles

Reducing one third the dose of porcine follicle-stimulating hormone did not affect the in vivo embryo production in Santa Inês ewes

Context Superovulation is still a main limitation of multiple ovulation and embryo transfer programs because of its high cost and the variability in the responses to the hormonal protocols used. Aims This study aimed to compare the effect of two doses of porcine follicle-stimulating hormone (pFSH) on follicular growth, superovulatory response, and in vivo embryo production of Santa Inês ewes. Methods A total of 40 multiparous ewes received a Day 0 estrus synchronization protocol and were superovulated with either 333 IU (G333, n = 20) or 500 IU (G500, n = 20) of pFSH. Ultrasonographic evaluations of ovaries were performed every 12 h, from the first pFSH dose until 60 h after the last dose. Ewes were naturally mated and submitted to non-surgical embryo recovery. A subsample of viable blastocysts (G333: n = 10; G500: n = 8) was stained with Nile Red to quantify lipid droplets. Key results The number of small, medium, and large follicles, and the size of the largest follicle, varied over time (P < 0.0001), even though there was no difference between the treatments. The pFSH dose also did not affect estrous behavior rate (95% vs 100%), superovulatory response (75% vs 70%), recovery rate (52.4% vs 56.4%), viability rate (73.8% vs 62.3%), recovered structures (5.9 vs 5.3), viable embryos (4.9 vs 3.7), and lipid accumulation in embryos (132.9 vs 129.4 arbitrary fluorescence units), for G333 and G500 respectively. Four ewes (10%) had premature luteal regression. It should be noted that all viable embryos recovered were Grade 1 or 2, that is, freezable embryos. Conclusions In conclusion, 333 IU of pFSH is enough to reach a similar superovulatory response as obtained from 500 IU of pFSH in Santa Inês ewes. Implications The use of lower doses of pFSH could reduce costs per embryo produced.

Support of the luteal phase in programs for transferring thawed embryos into the uterine cavity in patients with overweight and obesity

Introduction. Progesterone levels are a critical factor for embryo implantation in in vitro fertilization (IVF) programs, including thawed embryo transfer programs. Overweight/obese patients often have lower blood progesterone concentrations in the luteal phase during IVF cycles, which requires an individual approach to planning luteal support in this category of patients.Aim. To compare the pregnancy ratе and miscarriage rates up to 12 weeks of pregnancy in overweight/obese patients who underwent a program of transfer of thawed embryos into the uterine cavity, depending on the type and route of administration of gestagens.Materials and methods. The study included 76 overweight or obese patients. All patients were treated for infertility using a program for transferring a thawed embryo into the uterine cavity; luteal phase support was carried out either using micronized progesterone, identical to natural, – the drug Utrogestan in a daily dose of 800 mg intravaginally (40 patients), or combination therapy was prescribed – vaginal gel with progesterone 90 mg in combination with the synthetic progestin dydrogesterone in a daily dose of 30 mg, taken orally (36 patients).Results. The rates of pregnancy and miscarriage in the first trimester were comparable in both groups and did not depend on differences in luteal support.Conclusions. The formation of the luteal phase of the cycle in patients with overweight/obesity is equally effective using various forms of gestagens. The use of micronized progesterone may be preferable in patients with overweight/obesity in terms of the ability to monitor blood progesterone levels, a more favorable metabolic profile when used vaginally, and the possibility of switching to oral administration of the drug in the event of the development of adverse local events.

Factores que afectan la tasa de gestación con embriones cebú producidos in vitro en trópico

Objective. To study the factors affecting the success of embryo transfers (ET). Materials and methods. 1087 ET in zebu cattle were analyzed. The considered extrinsic factors of the donor cows were the cattle production unit from which they were sourced (n=13), amount of transfers in the unit (1 time, >1 time), geographical zone (n=4), period (dry or rainy) and year season; and the intrinsic factors were the breed of the bull and DC, semen, embryo quality and embryo developmental stage. Statistics were compiled with ci2 for the analysis of the main effects, and correlations were estimated through a multivariate clustering analysis. Results. The general pregnancy rate was 37.99±1.47, and there were differences (p<0.05) observed among the CPU (2.78–75%). The PR was higher in the dry than in the rainy period (44.55 vs 31.28%), and in fall and winter (p<0.05) than spring and summer (42.76, 43.98, 37.57 and 29.77%, respectively), and there were differences observed between the geographical zones as well (p<0.05). The PR was higher with excellent-quality embryos (p<0.05) than with good-quality embryos (38.9 vs. 26.3%). The period and year season had an effect over the RC (p<0.05), and the grouping analysis showed a correlation (r>0.90) between the period and year season during Oocyte pick-up (OPU) over the PR; moreover, semen, EQ and EDS had larger associations with the PR (r>0.80). Conclusions. Environmental conditions at the moment of OPU and EQ are factors worth considering in embryo transfer programs with zebu cattle using in vitro produced embryos in tropical conditions.

Validation of Hand Grading Technique of Corpora Lutea in Embryo Recipient Cows

The success of embryo transfer in cattle may depend on several factors. The blood progesterone level of the embryo recipient would be one of the main factors secondary to the size and quality of the corpus luteum. Per-rectal palpation and by-hand grading of corpora lutea have been practiced routinely, even under commercial embryo transfer programs in cattle. This experiment aimed to evaluate the accuracy of the per-rectal hand grading technique of mid-phase corpora lutea in embryo recipient cows. A group of healthy cows (Friesian× Jersey, n=25), which had been selected as recipient animals with the special consideration of reproductive history in an embryo transfer program, was used in this study. Estrous of those animals were synchronized using a standard progesterone intravaginal devise-PGF2α protocol. Conven-tional evaluation and grading of corpora lutea were conducted at the per-rectal hand grading as 'A', 'B', 'C' and 'Cystic' (If diameters; < 1cm=C, 1-1.9cm=B, 2-2.5cm= A, >2.5cm= Cystic). In this study, the accuracy of those hand-grading techniques was evaluated using ultra-sound scanning technology on the same day. Identification accuracy of grades C, B, A, and Cysts in hand grading technique was 45%, 56%, 67%, and 50%, respectively. The average accuracy in the hand grading technique was 52%, and identification accuracy as suitable (A or B) corpora lutea for embryo transfer was 76%. Results raised the 24% probable loss of embryo transferrable recipients due to the hand-grading technique. Further, 8% of unsuitable cows can be selected as embryo recipients due to the practice of hand-grading techniques at embryo transfer programs. Although higher accuracy is a characteristic of the hand grading technique, the technology causes considerable loss due to inaccurate selection probability of recipients at embryo transfer programs.

Assessment of endometrial and subendometrial three-dimensional power Doppler angiography evaluated by the VOCAL method in frozen-thawed embryo transfer cycles on hormone replacement therapy

BACKGROUND: The effectiveness of in vitro fertilization cycles / frozen-thawed embryo transfer cycles depends on a number of factors, the endometrial one being of great importance. Adequate endometrial and subendometrial blood supply is considered necessary for successful implantation. Currently, the possibilities of non-invasive assessment of the implantation properties of the endometrium are limited to the use of ultrasound. AIM: The aim of this study was to assess the performance of endometrial and subendometrial three-dimensional power Doppler angiography combined with the Virtual Organ Computer-aided Analysis (VOCAL) method in frozen-thawed embryo transfer cycles on hormone replacement therapy and compare the obtained data among the women examined. MATERIALS AND METHODS: This prospective study included 20 women. Doppler measurements were carried out three times — on the day of progesterone initiation, the day before embryo transfer and on the day of embryo transfer. The VOCAL software assessed the endometrial and subendometrial volume and blood flow indices such as vascularization index, flow index, and vascularization flow index. Patients were divided into two study groups depending on the onset of clinical pregnancy. RESULTS: On the day of progesterone initiation among patients who got pregnant, we observed higher vascularization (3.52 ± 1.99 vs. 1.05 ± 1.36; p = 0.03) and vascularization flow (1.54 ± 0.98 vs. 0.63 ± 0.55; p = 0.03) indices compared to women with a negative result. Moreover, endometrial vascularization index on the day of progesterone initiation was positively correlated with the estrogen dose among both pregnant (r = 0.61; p = 0.04) and non-pregnant (r = 0.9; p = 0.0008) women. No differences in subendometrial blood flow indices depending on the onset of pregnancy were obtained, just as endometrial blood flow indices the day before embryo transfer and on the day of embryo transfer were comparable between women in the both study groups. CONCLUSIONS: Three-dimensional power Doppler angiography evaluated by the Virtual Organ Computer-aided Analysis (VOCAL) method is a promising tool for non-invasive assessment of endometrial receptivity in frozen-thawed embryo transfer programs. However, further studies are required on a larger patient sample to form conclusions that are more accurate.

Evaluation of intrinsic and extrinsic factors affecting pregnancy rate in dual-purpose cows under tropical conditions.

Embryo transfer (ET) in bovines was created with the purpose of increasing the pregnancy rate (PR) of animals with high genetic value; however, multiple factors have been found to affect the success of this reproductive biotechnology. These factors are frequently grouped in intrinsic and extrinsic factors. Thus, the objective of the present experiments was to assess the effect of intrinsic and extrinsic factors on the pregnancy rate under tropical conditions. To do this a total of 648 embryo transfer (ET) procedures were performed between January and December 2021. The intrinsic factors were size and location of the corpus luteum, body condition, genetic group, age and parity; while extrinsic factors were location of the farm, environmental comfort, season in which the ET was carried out, prevailing weather conditions, and the preservation, quality, and the development stage of embryos at the time of ET. A χi2 was used for analysis of main effects, and logistic regression analysis to calculate the probability of pregnancy and the association between intrinsic or extrinsic factors; additionally, a multivariate analysis of data clusters was used to find a linkage between the effects. While recipient female age had a negative effect (Odds ratio = 0.345-0.871) on PR (p < 0.05), being higher in younger cows, the rest of the intrinsic factors did not affect the PR. The significant (p < 0.05) extrinsic factors were THI category, season of year and type of embryo preservation, showing that the highest PR (p < 0.05) was obtained in the comfort THI category, during the winter season and using fresh embryos for transfer. The clustering analysis did not show any linkage between PR and intrinsic factors, while a linkage (p < 0.05) was found with season of the year and embryo preservation as extrinsic factors. It is concluded that age of the recipient cow and environmental conditions at the time of the embryo transfer are key factors to be considered for a successful pregnancy rate from in-vitro ET programs using dual-purpose cows under tropical conditions.

Cytokine profile in peripheral blood mononuclear cells differs between embryo donor and potential recipient sows.

Pregnancy success relies on the establishment of a delicate immune balance that requires the early activation of a series of local and systemic immune mechanisms. The changes in the immunological profile that are normally occurring in the pregnant uterus does not take place in cyclic (non-pregnant) uterus, a fact that has been widely explored in pigs at the tissue local level. Such differences would be especially important in the context of embryo transfer (ET), where a growing body of literature indicates that immunological differences at the uterine level between donors and recipients may significantly impact embryonic mortality. However, whether components of peripheral immunity also play a role in this context remains unknown. Accordingly, our hypothesis is that the immune status of donor sows differs from potential recipients, not only at the tissue local level but also at the systemic level. These differences could contribute to the high embryonic mortality rates occurring in ET programs. In this study differences in systemic immunity, based on cytokine gene expression profile in peripheral blood mononuclear cells (PBMCs), between embryo-bearing donor (DO group; N = 10) and potential recipient sows (RE group; N = 10) at Day 6 after the onset of the estrus were explored. Gene expression analysis was conducted for 6 proinflammatory (IL-1α, IL-1β, IL-2, GM-CSF, IFN-γ, and TNF-α) and 6 anti-inflammatory (IL-4, IL-6, IL-10, IL-13, TGF-β1, and LIF) cytokines. All cytokines were overexpressed in the DO group except for IL-4, suggesting that stimuli derived from the insemination and/or the resultant embryos modify the systemic immune profile in DO sows compared to RE (lacking these stimuli). Our results also suggest that certain cytokines (e.g., IL-1α and IL-1β) might have a predictive value for the pregnancy status.

Impact of negative energy balance and postpartum diseases during the transition period on oocyte quality and embryonic development in dairy cows.

Transition period is a critical time for dairy cows because a large proportion of clinical and subclinical diseases are observed in the first month after parturition. Occurrence of negative energy balance is associated with depressed immunity and these conditions can affect oocyte quality and further embryonic development. The aim of this study was to assess the effects of negative energy balance-associated disorders on in vitro embryo production (IVP) in dairy cattle. We hypothesized that subclinical metabolic and/or inflammatory disorders have a negative effect on oocyte developmental competence and morphokinetic parameters of the resulting embryos. The study was conducted on 30 lactating Holstein-Friesian cows which were assigned into four groups: healthy (HEAL, n = 6), metabolic disease (META, n = 8), inflammatory disease (INFL, n = 8), or combined metabolic and inflammatory disease (COMB, n = 8). Ovum pick-up (OPU) was performed twice weekly on all cows over a period of four weeks (n = 8 OPU sessions/cow) starting on the fifth week postpartum, and the collected oocytes were subjected to routine IVP. Donor's health status did not affect the number of oocytes/OPU or the recovery rate (p > 0.05). The number of quality 1 oocytes collected from INFL and COMB cows was lower compared to HEAL cows (p < 0.05). Also, the percentage of quality 1 embryos was reduced in META and COMB compared to HEAL cows (p < 0.05). Cleavage, blastocyst and hatching rates were similar among groups (p > 0.05). Presence of disease did not affect the time required by zygotes to reach specific developmental stages, as recorded by means of time-lapse monitoring. Nevertheless, there was a higher probability of direct cleavage after IVF in oocytes of COMB cows compared to those of HEAL cows (p < 0.05). In conclusion, oocytes and embryos derived from dairy cows diagnosed with subclinical metabolic and/or inflammatory diseases during the transition period showed reduced quality but similar developmental potential and morphokinetics when compared to healthy cows. These results shed light on the consequences of subclinical disease on embryonic development in dairy cows which might be important for embryo transfer programs.

Evolution over the last 40 years of the assisted reproductive technologies in cattle - the Brazilian perspective for embryo transfer and resynchronization programs (part II).

The productivity of the beef and dairy industries depends directly on the reproductive efficiency and genetic gain of the herd, which are directly associated with the appropriate use of Assisted Reproductive Technologies (ARTs). The objective of this review is to show from a Brazilian perspective the evolution over the last 40 years of ARTs related to ovulation resynchronization programs and embryo transfer in cattle. Despite significant improvements and high fertility obtained in timed artificial insemination (TAI) protocols (Sales et al., 2024 - Part I), the improvement of the use of in vitro-produced embryos, development of resynchronization programs, and the advance in Doppler ultrasonography (Doppler-US) for reproductive assessments of bovine females were the ARTs that presented the greatest relevance on reproductive effectiveness in cattle. In the last seven years, the embryo transfer (ET) technology using in vitro-produced (IVP) embryos took over the conventional ET of in vivo produced embryos after donor's superovulation. Also, procedures and pregnancy rates after ET of IVP embryos were improved in dairy and beef operations. The Doppler-US allows the identification of non-pregnant females at an early stage based on the evaluation of blood perfusion of the corpus luteum. Recent studies in beef and dairy cows indicate satisfactory accuracy when Doppler-US is used at 20-22 days after TAI. Consequently, super-early resynchronization programs have been developed and are being implemented in commercial programs, thereby facilitating earlier conception through the use of semen from superior bulls, providing genetic and economic improvements in herds. Likewise, the assessment of luteal function by Doppler-US allows the selection of embryo recipients with greater receptivity, and consequently may increase the effectiveness of timed ET programs.

From the laboratory to the field: how to mitigate pregnancy losses in embryo transfer programs?

Pregnancy losses negatively affect the cattle industry, impacting economic indices and consequently the entire production chain. Early embryonic failure has been an important challenge in the embryo industry because proper identification of embryo death at the beginning of gestation is difficult. This review aimed to provide a better understanding on reproductive failure and the relationship between early embryonic loss and different reproductive biotechniques. This review also considers insights and possible strategies for reducing early embryonic loss. The strategies addressed are as follows: i) great impact of rigorous embryo evaluation on reducing embryo losses; ii) selection of recipients at the time of transfer, taking into account health and nutritional status, and classification of the corpus luteum using ultrasound, either in area or vascularization; and iii) paternal effect as one of the factors that contribute to pregnancy losses, with a focus on embryo transfer.

Ovarian Follicular Development Study in Jersey Crossbred Cows Reared in India

Ovarian follicular wave pattern studies provide the basis for applying reproductive intervention for improving fertility and improving the success of embryo transfer programmes in cattle. Four apparently healthy non-pregnant, pluriparous crossbred Jersey cows reared in a local farm located at Tirupur were utilized for this study. The evaluation was performed more than one plane, and all the measurable follicles (&gt;3mm) were counted and recorded every other day. Various follicular dynamics related parameters were studied such as day of wave emergence, dominant follicle, static phase of dominant follicle, regressing phase of dominant follicle, day of maximum diameter, maximum size, duration of growth, growth rate, duration of atresia, rate of atresia and duration of detection. The Ultrasonographic evaluation was performed every other day throughout an estrous cycle starting from observed estrus (Day 0) to the subsequent standing estrus. A total of 10 normal estrous cycles were monitored for follicular wave pattern, in which 8 out of 10 (80 per cent) were two wave and 2 out of 10 (20 per cent) were three wave estrous cycles. The mean length of 2-wave estrous cycle was 19.25±0.41 days and 3-wave estrous cycle was 21.50±0.50 days. It was concluded that Jersey crossbred cows frequently had 2 wave estrous cycle with pre-ovulatory follicle size 12.62±0.94mm with the growth rate of 1.13±0.12mm/day and the size of pre-ovulatory follicle in 3-wave estrous cycle was lower (10.75±1.25mm) than 2-wave estrous cycle.

119 Use of lactating females with nursing calves as recipients in an embryo transfer program in camel (Camelus dromedarius)

119 Use of lactating females with nursing calves as recipients in an embryo transfer program in camel (Camelus dromedarius)

Effect of strategies to increase progesterone levels on fertility of bovine embryo transfer recipients - A meta-analysis

The pregnancy rate following embryo transfer (ET) is a very important factor in the success of embryo production programs. Different strategies were therefore developed to increase pregnancy rates. The aim of this meta-analysis was to investigate the effects of hormone treatments used to increase the success of embryo transfer programs on pregnancy rates. A meta-analysis was performed of 46 trials from 39 publications involving treated (n = 7856) and control (n = 6663) cattle. The meta-analysis explained the effect size with its 95 % confidence interval (CI) for pregnancy per embryo transfer (P/ET) after hormonal treatment under different moderators. Hormonal support was found to increase P/ET compared to the control group (P < 0.05). However, GnRH treatment was found to increase P/ET by approximately 4.3 % and hCG treatment by 8.0 %. Progesterone supplementation was not found to have a statistically significant effect on P/ET. In addition, GnRH treatment significantly increased P/ET when used to transfer in vitro or frozen-thawed embryos or in studies using cows as recipients. It was observed that hCG treatment had a positive effect on P/ET according to all moderators. Progesterone supplementation significantly increased P/ET when frozen embryos were transferred and reduced P/ET, especially in publications where fresh or in vitro produced embryos were transferred or cows were used as recipients. The results of this meta-analysis showed that the use of GnRH, and hCG, in bovine embryo transfer programs increased P/ET, whereas the use of progesterone had no effect on P/ET. However, it was found that P/ET could increase/decrease depending on the moderator.

Vaginal Cytology as a tool for estrus detection improves the success of artificial insemination in water buffalo

Estrus detection in water buffalo is affected by the high incidence of poor manifestation inherent in this animal species. This affected the success rate of Artificial Insemination (AI) and Embryo Transfer (ET) due to the failure of perfect timing in AI and embryo-recipient synchrony in ET. While various ways of estrus detection were reported, the accuracy was interfered with by other symptoms that signify the health condition rather than the reproductive status of the animal. This results in a low conception rate and long calving intervals in AI and ET programs. Vaginal Cytology is a simple clinical tool of estrus detection that can also detect the pathological status of the reproductive tract and the perfect time for AI. While this is greatly used in canines, application in large animals was limited. The need to collect the swab from animals in the field and bring the smeared sample for analysis to the laboratory hindered its use and application. Our study, however, showed that by adopting this tool in estrus detection, increase in conception rate and calf production were achieved. A >60.0% cornification with the presence of >10 mm Graafian follicle is enough indicators of the perfect time for AI resulting in 80-100% conception. The development of a water buffalo vaginal chart helped determine the time of estrus. Strategies to adopt this tool for improved livestock reproduction are warranted.

Age and treatment on the day of embryo transfer in recipient mares affect likelihood of pregnancy.

This retrospective evaluation of data from a large commercial embryo transfer facility aimed to determine the extent to which age and treatment on the day of embryo transfer in recipient mares influence the likelihood of pregnancy. Embryo recovery was carried out on days 8-10 post-ovulation using transcervical uterine flushing. Recipient mares grouped according to their age were treated once on the day of embryo transfer (Day 3-8 post ovulation) and were assigned randomly to 1 of 3 groups: Mares in Group A (n=101) received antispasmodic, antimicrobial, and anti-inflammatory drugs. Mares in Group B (n=100) received gentamicin and flunixin meglumine. Group C (control) (n=103) did not receive any treatment. Detomidine (0.008 mg/kg bwt i.v.) was administered to all recipients before transfer of the embryo. The influence of treatment and recipient´s age was calculated using binary logistic regression. Day 16 post-transfer pregnancy rates were highest in Group A (74/101, 73.3a%), when compared to Group B (60/100, 60%), and Group C (57/103, 55.3b%) (a vs b, p<0.05). Pregnancy loss rates at D45 were not different between groups, A (8/74, 10.8%), B (5/60, 8.3%), and C (6/57, 10.5%), respectively (p>0.05). Pregnancy losses were increased in recipient mares 17-22 years (33.3a%) compared to younger recipient mares (2-6 years 7b%, 7-11 years 10%, 12-16 years 8b%) (a:b p<0.05). The regression model showed that the predicted probability for pregnancy after embryo transfer decreased as the age of the recipient mare increased for treated recipients in Group A (p=0.012), there was no effect of treatment and recipient´s age in Group B, and a decreased likelihood of pregnancy in recipients of advanced age (≥12 years of age) in untreated recipients (group C). Likelihood of pregnancy increased following single administration of antispasmodic, antimicrobial, and anti-inflammatory drugs at the time of embryo transfer in recipients 2-12 years of age. Likelihood of pregnancy in recipients decreased in recipients≥12 years of age. These results, obtained under the conditions of a large commercial embryo transfer program, offer an opportunity to improve pregnancy rates in recipient mares≤12 years of age.

Enhancement of preimplantation mouse embryo development with optimized in vitro culture dish via stabilization of medium osmolarity.

We evaluated the efficacy of the newly developed optimized in vitro culture (OIVC) dish for cultivating preimplantation mouse embryos. This dish minimizes the need for mineral oil and incorporates microwells, providing a stable culture environment and enabling independent monitoring of individual embryos. Mouse pronuclear (PN) zygotes and two-cell-stage embryos were collected at 18 and 46 hours after human chorionic gonadotropin injection, respectively. These were cultured for 120 hours using potassium simplex optimized medium (KSOM) to reach the blastocyst stage. The embryos were randomly allocated into three groups, each cultured in one of three dishes: a 60-mm culture dish, a microdrop dish, and an OIVC dish that we developed. The OIVC dish effectively maintained the osmolarity of the KSOM culture medium over a 5-day period using only 2 mL of mineral oil. This contrasts with the significant osmolarity increase observed in the 60-mm culture dish. Additionally, the OIVC dish exhibited higher blastulation rates from two-cell embryos (100%) relative to the other dish types. Moreover, blastocysts derived from both PN zygotes and two-cell embryos in the OIVC dish group demonstrated significantly elevated mean cell numbers. Use of the OIVC dish markedly increased the number of cells in blastocysts derived from the in vitro culture of preimplantation mouse embryos. The capacity of this dish to maintain medium osmolarity with minimal mineral oil usage represents a breakthrough that may advance embryo culture techniques for various mammals, including human in vitro fertilization and embryo transfer programs.

Embryo yield and quality in superovulated Simmental donor cows following oral supplementation with different sources of omega-3 and omega-6 fatty acids

Owing to contradictory results with respect to the yield and quality of embryos after supplementation with omega-3 fatty acids, this study sought to determine the effect of an oral supplement containing sources of omega-3 and omega-6 fatty acids on the ovarian response and embryo quality after superovulation. Cows were allocated to receive one of three oral supplement regimens. In the control (CO) group (n = 9), cows were fed a control supplement without fatty acids. The cows in the soybean oil (SO) (n = 8) and linseed oil (LO) (n = 8) groups received supplements containing SO or LO, respectively. Supplements were administered for 28 days, commencing 7 days before the onset of estrus synchronization until the day of embryo collection. The estrous cycle of all cows was synchronized by inserting a controlled internal drug release (CIDR) device (progesterone 1.38 g), followed by the administration of estradiol benzoate 2.5 mg. The CIDR device was withdrawn 7 days after insertion, followed by intramuscular administration of dinoprost 25 mg. Superovulation was induced via the administration of 152 mg of follicle-stimulating hormone (Folltropin-V) in tapered doses, starting 72 h before CIDR withdrawal. The embryos were collected 6 days after artificial insemination. The estrous response, onset of estrus after CIDR withdrawal, and number of ovulations were similar among the experimental groups (p > 0.05). The mean number of transferable embryos (grades 1 and 2) was higher in the LO group compared to the CO group (9.0 vs 3.2; p < 0.05). Although the number of transferable embryos (grades 1 and 2) was greater in the LO group than that in the SO group, the difference was not statistically significant (9.0 and 4.4; p > 0.05). In conclusion, oral supplementation with LO for 28 days increased the yield of transferable embryos, which could potentially improve the profitability of embryo transfer programs in cattle.

Assessment of Luteal Function Using Rectal Palpation, B-Mode Ultrasonography, and Progesterone Determination to Improve Recipient Selection in Embryo Transfer Programs.

Proper selection of recipients determines the success of embryo transfer (ET) programs. Therefore, the objectives of this study were to assess the accuracy of rectal palpation (RP) in selecting recipients according to the size and firmness of their corpus luteum (CL) compared to ultrasonography (US) and progesterone determination (P4); to check if US or P4 provide additional information to RP with regard to selecting animals with higher odds of maintaining the pregnancy; and to verify the reliability of the presence of a cavity and the volume of the CL within the ovary (%CLOV) as predictors of the ET outcome. In Experiment 1, measurements for the largest and minor diameter (LADCL and MIDCL), CL area, and P4 at ET day were collected, as well as the RP score, in 94 heifers. In Experiment 2, measurements for the LADCL, MIDCL, CL volume, %CLOV, and presence of a cavity were collected, as well as data about the procedure and metabolic markers, in 108 heifers. No differences were found in Experiment 1, whereas in Experiment 2, just a tendency was observed for the variable of veterinarian. Consequently, these results suggest that RP and US are useful methods to select recipients with, that US and P4 do not offer additional data to use to select animals with higher odds of maintaining pregnancy, and that neither %CLOV nor cavitary CL were good indicators for pregnancy rates.

Anti-Müllerian hormone in female dromedary camel and its association with super-ovulatory response in embryo donors

Anti-Müllerian hormone (AMH) has a conserved role in regulating the reproductive cycle in several species. Its circulating concentration reflects the size of the growing primordial follicle reserve and is a reliable predictor of superovulation response in embryo/oocyte donors. This study investigated the possible application of AMH measurement in dromedary camels (Camelus dromedarius) multiple ovulation embryo transfer programs. In experiment 1, the follicular cycle of synchronized and naturally cycling camels (n = 12) was monitored. Blood was collected at 6 timepoints in 2 consecutive cycles corresponding to emergence, mid-cycle, and dominance in both group and hormonal fluctuations were evaluated for repeatability of measurements within and between cycles. In experiment 2, the correlation between circulating AMH concentrations prior to initiation of superovulation and the outcome of superovulation was evaluated. The results were compared between donors with higher (n = 7) and lower than median (n = 8) AMH values. Mean AMH concentrations in synchronized and non-synchronized camels were 1.46 ± 0.15 and 0.95 ± 0.09, respectively. Intercycle and intracycle values of AMH showed high repeatability in camels of both groups (>96.4% and >92.74%, respectively) with significant correlations between values at different stages of the ovarian cycle (Emergence and mid-cycle: R2 = 0.82; emergence and. dominance: R2 = 0.86; Mid-cycle and dominance: R2 = 0.93, P < 0.05). Total follicles, CLs, and recovered embryos were highly correlated with AMH values prior to superovulation (R2 = 0.64, R2 = 0.77, and R2 = 0.64, respectively, P < 0.05). A greater number of developed follicles prior to mating (17.00 ± 2.09 vs. 7.62 ± 1.06), CLs (12.58 ± 1.36 vs. 5.12 ± 0.93), transferable (10.85 ± 1,31 vs. 3.37 ± 0.82), and spherical embryos (8.14 ± 1.07 vs. 2.62 ± 0.7) were observed in camels with higher than median concentrations of AMH (P < 0.05). Fluctuations in estradiol and progesterone did not affect variations in mean AMH values (r2 < 0.19 and r2 < 0.24, respectively, P > 0.05). In conclusion, highly consistent AMH values in dromedary camels are a reliable predictor of superovulation response and outcome in dromedary camels.

Use of Doppler ultrasonography for selection of recipients in embryo transfer programs in horses

We aimed to evaluate the impact of corpus luteum (CL) and uterine characteristics accessed by B-mode and Color-Doppler ultrasonography in recipient mares at the time of embryo transfer (ET) on pregnancy outcomes. Recipient mares (n = 110), between days 3–9 after spontaneous ovulation, received a fresh embryo. Immediately before ET, the reproductive system was assessed by transrectal palpation for the following parameters: uterine tone (0–3), CL echogenicity (0–6), CL type (homogeneous, trabecular or anechoic center), luteal area (cm2), uterine echogenicity (0–3), uterine edema (0–3), luteal blood perfusion (0–100%) and uterine blood perfusion (1–4). Additionally, a blood sample was collected by puncture of the jugular vein for plasma P4 dosage. Retrospectively, recipients were classified according to the luteal area (small [≤ 6 cm2] or large [> 6 cm2]), luteal blood perfusion (low [≤ 55%] or high [> 55%]), and plasma concentration of P4 (low ≤ 9.98 ng/mL or high > 9.98 ng/mL). Pregnancy diagnosis was performed at 12 and 30 days of gestation. Luteal blood perfusion was significantly higher (P = 0.04) in pregnant recipients (n = 83) than in non-pregnant recipients (n = 27). Overall P/ET was higher (P ≤ 0.02) in mares with high luteal blood perfusion and high P4. Luteal blood perfusion was the most adequate significant (P = 0.01) predictor of pregnancy compared with the luteal area and plasma P4 concentration. Only luteal blood perfusion showed a linear (P = 0.03) and cubic (P = 0.004) effect on P/ET. In conclusion, CL blood perfusion determined by color-Doppler can be used in real-time to select recipients with the greatest chance of maintaining pregnancy in equine ET programs.