Intrinsic determinants and predictors of superovulatory yields in sheep: Circulating concentrations of reproductive hormones, ovarian status, and antral follicular blood flow

The effect of flunixin meglumine on the premature regression of corpus luteum, recovery rate, and embryo production in superovulated Dorper ewes

This study evaluated the use of flunixin meglumine to prevent the occurrence of premature corpus luteum (CL) regression in superovulated ewes, improving embryo recovery and viability. Ewes (n=23) submitted to conventional superovulatory protocol and laparoscopic artificial insemination were treated with 2.2 mg/kg/day of flunixin meglumine (FLU, n=12) or 1.5 mL saline solution (CONT, n=11) on Days 2, 3, and 4 (Day 0 = 48 h after device removal). Serum progesterone (P4) concentrations were measured (Day 1-6). Ultrasound (US, Days 3 and 6) and laparoscopic evaluation (Day 6) were performed to identify luteinized structures. In the US, laparoscopy, and P4 assessments, the percentage of ewes with premature CL regression differed (P<0.05) between CONT (54.5; 63.6; and 54.5 %) and FLU (0.0; 0.0; and 0.0 %), respectively. The US exams revealed the effect (P<0.05) of treatment on the number of regressing CL between CONT (1.4 ± 0.6) and FLU (0.0 ± 0.0). Greater (P<0.05) number of normal CLs (10.5 ± 1.8 vs. 4.4 ± 1.5), ova/embryos (9.1 ± 2.1 vs. 3.7 ± 1.3), viable embryos (5.1 ± 1.1 vs. 2.6 ± 1.2), and recovery rate (79.5 ± 9.6 vs. 41.3 ± 15.0 %) were observed in FLU compared to CONT, respectively. The embryo viability rate did not differ (P>0.05) between FLU (60.7 ± 10.5 %) and CONT (45.5 ± 16.1 %). In conclusion, the flunixin meglumine protocol was able to prevent the occurrence of premature CL regression in superovulated ewes, increasing the recovery rate and embryo production.

Impact of antral follicle count on follicular-luteal characteristics, superovulatory response, and embryo quality in Sahiwal cows

The study aimed to evaluate the effect of antral follicle count (AFC) on follicular and luteal development during the estrous cycle and superovulatory period, as well as on superovulatory response and in vivo embryo quality within the MOET program. A total of 48 estrus-induced (500 μg PGF2α, Single dose, IM) Sahiwal cows (Bos indicus) with a BCS between 3.5 and 4.0 were selected for the study. On the day of wave emergence, the animals were divided into two groups based on the AFC, i.e., low AFC (≤18) and high AFC (>18). Both the groups were monitored daily using B-mode ultrasonography (USG) for one cycle, and the superovulation protocol was initiated on the 9th day of the subsequent estrous cycle. A total of 240 μg of FSH in eight divided doses were given in a tapering sequence for 4 days and simultaneous administration of 500 μg PGF2α, along with the fifth dose of FSH. Donors were inseminated at superovulatory estrus using double straws of high-quality frozen semen thrice at 12-h intervals, and non-surgical flushing was performed on day 7 of the superovulatory estrus followed by embryo searching and evaluation under a stereo zoom microscope. Ovulatory waves of the high-AFC Sahiwal cows have significantly (p ≤ 0.05) larger sizes of preovulatory follicles (POF) (12.06 ± 0.19 mm vs 11.56 ± 0.16 mm) and corpus luteum (CL) (19.57 ± 0.28 mm vs 18.26 ± 0.35 mm), as compared to low AFC. The ovarian size was significantly (p < 0.0001) larger in cows with high AFC during the superovulatory protocol. The number of large, medium, and small follicles was significantly (p < 0.0001) high on the day of superovulatory estrus (SOE), PGF2α administration, and initiation of superovulatory protocol, respectively, in high AFC. Donors with high AFC had a notably greater (p < 0.0001) count of CL and embryos retrieved per flushing, including excellent and fair-quality embryos. A strong association (p < 0.0001) between high AFC and ovarian size (r = 0.9136), superovulatory response (r = 0.9350), and embryo quality (x2 = 8.788; p = 0.032) and number (r = 0.9858) were also recorded. Based on these results, AFC is considered a dependable indicator for forecasting reproductive capacity. Bos indicus donors with an average AFC of 30 or higher are recommended.

The pFSH dose affects the efficiency of in vivo embryo production in Santa Inês ewes

This study compared the follicular growth, superovulatory response, and in vivo embryo production after administering two doses of porcine follicle-stimulating hormone (pFSH) in Santa Inês ewes. The estrous cycle of 36 multiparous ewes was synchronized with the Day 0 protocol and superovulated with 133 mg (G133, n=18) or 200 mg (G200, n=18) of pFSH. Ultrasonographic evaluations of the ovaries were performed, ewes were mated and submitted to non-surgical embryo recovery. Viable blastocysts were stained with Nile Red and Hoechst. The G200 had a greater number of medium and large follicles, as well as a larger size of the third largest follicle. A total of 97.2% (35/36) of the ewes came into estrus and it was possible to transpose cervix in 80.6% (29/36). There were no effects of treatments in the response to superovulation, the proportion of ewes in which was possible to transpose the cervix, the number of corpora lutea, the number of anovulatory follicles, the proportion of ewes flushed with at least one recovered structure, number of recovered structures, number of viable embryos, viability rate, and recovery rate. The G200 ewes were in estrus for a longer period of time than the G133 ewes (54.0 ± 4.5 h vs. 40.3 ± 3.6 h) and produced more freezable embryos (6.5 ± 1.6 vs. 2.3 ± 0.7) than G133. Both doses promoted an efficient superovulatory response and did not affect embryonic lipid accumulation. The dose of 200 mg of pFSH showed greater potential to increase the superovulatory response, as it increased follicular recruitment and the recovery of freezable embryos.

Ovarian and uterine arteries blood flow velocities waveform, hormones and nitric oxide in relation to ovulation in cows superstimulated with equine chorionic gonadotropin and luteolysis induction 10 and 17 days after ovulation

To investigate the ovarian responses, ovarian and uterine hemodynamics, circulating ovarian hormones, and nitric oxide (NO) with their relations in superstimulated cows. Eight Holstein Friesian dry cows previously synchronized with CIDR underwent rectal Doppler ultrasound scanning and blood sampling after administrating eCG (1500 I.U) on day 10 of the second ovulation (day -5). Cows were treated with 12.5 mg prostaglandin F2α (PGF2α) on days 10 and 17 after ovulation. Estradiol, progesterone, and NO were measured. Results showed that from ≥ 13 follicles, five follicles ovulated from both ovaries. The ovulated follicles increased antrum colored area and colored area % till day -1. The developed corpora lutea (CLs) attained similar diameter, area, colored area, and colored area % from day 2 till day 15. The peak point of velocity (PSV) of uterine arteries decreased while that of ovarian arteries increased from day -4 to day 0. Both ovarian arteries diameter, resistance index (RI), PSV, end velocity (EDV) and systolic/diastolic ratio (S/D) positively correlated (P < 0.0001), but their pulsatility index (PI) negatively correlated (P < 0.0001). The uterine arteries PI, RI, PSV, EDV, time average velocity (TAMV) and S/D negatively correlated (P < 0.0001) but their diameters positively correlated. Estradiol increased but progesterone decreased from day -5 till day 0. After ovulation, P4 reached maximum values on day 9 and started to decrease till day 19.NO showed one peak on day -3 and another one from day 3 to day 9. Conclusions: Blood flow of ovarian arteries is different from uterine arteries and depended on pre- or post-ovulation.

Intravaginal progesterone device reinsertion during the early luteal phase affects luteal function and embryo yield in superovulated ewes

This study checked the efficacy of progesterone (P4) device reinsertion during the early luteal phase on luteal function and embryo yield in superovulated crossbred ewes. Twenty multiparous ewes received an intravaginal P4 device for nine days (D0 to D9) followed by six decreasing doses (25, 25, 15, 15, 10, 10%) of 133 mg pFSH i.m. at 12 h intervals, starting 60 h before P4 device removal. Ewes were naturally mated at 12 h intervals while in estrus. On D13, ewes with viable corpora lutea (CL; n = 19) were equally allocated for receiving their P4 device reinsertion (G-P4; n = 10) or not (G-Control; n = 9). On D17, the P4 device was removed, and all females received the cervical relaxation protocol 16 h to 20 min before non-surgical embryo recovery. CL count and their functionality classification were performed on D13 and D17 by transrectal B-mode and color Doppler ultrasonography (US). Plasma P4 concentrations (ng/mL) of G-P4 ewes increased (P < 0.05) over the days, being greater on D17 (9.2 ± 2.8) than on D9 (1.9 ± 0.7) and D13 (1.6 ± 0.4). The overall CL count per ewe tended to be greater (P = 0.09) in G-P4 compared with G-Control. The occurrence of premature regression of corpora lutea did not differ (P > 0.05) between G-P4 (30.0%) and G-Control (44.4%). The number of ova/embryos recovered was greater (P < 0.05) in G-P4 (11.6 ± 2.9) compared with G-Control (3.7 ± 2.0), respectively. Altogether, the reinsertion of the P4 device for four days after superovulation in ewes promotes greater P4 concentrations, resulting in greater ova/embryos recovered.

Luteal Function, Biometrics, and Echotextural Attributes in Santa Inês Ewes Superovulated with Different Total Doses of Porcine Follicle-Stimulating Hormone

Premature regression of corpora lutea (PRCL) may adversely affect the outcome of hormonal ovarian superstimulation in small ruminants, and the total dose of exogenous gonadotropins used may be one of the causes of this condition. There were two major objectives of the present study: (1) to evaluate the effects of different superovulatory doses of porcine follicle-stimulating hormone (pFSH) on the biometry, blood perfusion (Doppler), and echotextural characteristics of luteal structures; and, (2) to determine the usefulness of biometric, vascular, and echotextural luteal variables, as well as measurements of circulating progesterone (P₄) concentrations for early detection of PRCL in superovulated Santa Inês ewes. Twenty-seven Santa Inês ewes received an intravaginal P₄-releasing device (CIDR) from Days 0 to 8 (Day 0 = random day of the anovulatory period). An IM injection of d-cloprostenol (37.5 μg) was given at the time of the CIDR insertion and withdrawal. On Day 6, all the ewes received 300 IU of eCG IM and were divided into three treatment groups (each n = 9): G100 (100 mg); G133 (133 mg); and G200 (200 mg of pFSH) administered IM every 12 h in eight injections. Transrectal ovarian ultrasonography and jugular blood sampling for serum P₄ measurements were performed on Days 11 to 15. On the day of embryo recovery (Day 15), all the ewes underwent diagnostic videolaparoscopy and were classified, based on their luteal characteristics, into three response groups: nCL (ewes with normal CL only); rCL (ewes with regressing CL only); and ewes with both nCL and rCL following the superovulatory regimen. Our present results indicate that the total pFSH doses of 100 mg and 200 mg result in similar ovulatory responses and luteal function/biometrics, although the percentage of donor ewes with nCL was greater (p < 0.05) for G100 compared with the G200 animals. An application of 133 mg of pFSH was associated with diminished luteogenesis. Lastly, circulating P₄ concentrations, ultrasonographic estimates of total luteal area, and CL pixel heterogeneity (standard deviation of numerical pixel values) are promising markers of luteal inadequacy in superovulated ewes.

Hormonal indexes as predictors of porcine reproductive traits

The aim of the present study was to examine the applicability of several hormonal indexes for early prediction of puberty and reproductive state in pigs. For this purpose, we have compared the level of hormones leptin, estradiol, progesterone, and IGF-I in the blood of gilts at 150 days of age and their indexes of puberty and ovarian state at the age of 200 days. The association between blood leptin, estradiol, progesterone, and IGF-I and indexes of future reproductive state has been demonstrated. High blood concentrations of leptin and IGF-I levels were associated with relatively low reproductive traits, while high levels of estradiol and progesterone were associated with future high reproductive indexes. These observations are the first demonstration of the applicability of these endocrine indexes for prediction of porcine reproductive traits.

Analytical Validation of the IMMULITE® 2000 XPi Progesterone Assay for Quantitative Analysis in Ovine Serum

Monitoring circulating progesterone (P4) concentration is an important component of basic and applied reproduction research and clinical settings. IMMULITE® 2000 XPi (Siemens) is a newly upgraded fully automated immunoassay system marketed for human use to measure concentrations of different analytes including P4. Our objective was therefore to characterize the analytical performance of the IMMULITE® 2000 XPi P4 immunoassay across the reportable range in ovine serum. This validation of analytical performance included determining (1) linearity, (2) precision through within-run, and between-run coefficient of variation (CV) calculations, (3) accuracy through bias calculations for spiking-recovery bias and interlaboratory (range and average based) bias for two laboratories across the reportable range (0.2−40 ng/mL). The average within-run and between-run precision (CV%) across the reportable range of the IMMULITE® 2000 XPi P4 immunoassay for serum P4 concentration were both <5%, ranging between 2−8%. The average Observed Total Analytic Error (TEo) reported here for serum P4 concentration across the reportable range was ~30%, ranging from 14.8−59.4%, regardless of the considered bias. Based on these data we conclude that the automated IMMULITE® 2000 XPi P4 immunoassay provides a precise, accurate, reliable, and safe method for measuring P4 concentration ovine serum.

Use of logistic models to evaluate the response of superovulation treatment and embryo production in Santa Inês ewes

The study aimed to verify the influence of the FecG^E mutation in superovulated ewes and to evaluate the probability of logistic models to determine the response capacity of these ewes to superovulatory treatment. Santa Inês ewes (n = 29) were genotyped for the FecG^E mutation and separated for their genotype group in carriers of the mutant E allele (FecG^E/E, FecG^+/E) and non-carrier (FecG^+/+) alleles. The ewes underwent hormonal treatment for superovulation. Aside from the genotypes, variables included in the statistical model were reproductive status (empty, early lactation, or late lactation), age (> or < 6 years), and number of births (nulliparous, primiparous, multiparous). The carriers of the mutation could be discriminated from the non-carriers based on the number of corpora lutea, rate of frozen embryos, and fecundity. Recovery rate was significantly higher (P < 0.05) in FecG^E/E (94.31%) compared to FecG^+/E (63.15%) and FecG^+/+ (61.90%) (P < 0.05), whereas fecundity rate of FecG^+/+ ewes (50.76%) was significantly higher than FecG^+/E (18.96%) and FecG^E/E (32.53%) (P < 0.05). We determined in this study that the response to superovulation and embryo production can be discriminated between FecG^E/E and FecG^+/E ewes in relation to the FecG^+/+ genotype. Logistic models that included reproductive status and mutation, or reproductive status and age, or reproductive status and number of births were effective in predicting the response to superovulatory treatment.

Multiple ovulation and embryo transfer in sheep: Effects of embryo developmental stage and quality on viability in vivo under farm conditions

Multiple ovulation and embryo transfer (MOET) technologies are integral to genetic improvement programs in the sheep industries. Despite the protocols being well established, previous findings regarding the effects of embryo properties on MOET success remain contradictory. The objective of this study was to determine the effects of embryo developmental stage and quality on embryo viability following transfer to recipient ewes. Data including details of 377 embryos collected from 45 Merino donor ewes were obtained from MOET trials conducted on three separate farms on day 6 after laparoscopic artificial insemination (AI). A total of 270 embryos were classified as being of transferrable grade (grade 1: n = 233; grade 2: n = 37). One or two transferrable grade embryos were transferred to each of 256 synchronised recipient ewes and pregnancy diagnosis was performed on day 36 after embryo transfer. Embryos at the hatched blastocyst stage tended to have greater viability in vivo compared to embryos at the late morula stage (59.0 ± 10.6% vs. 36.2 ± 9.7%; P = 0.083). The viability of grade 1 embryos was greater than that of grade 2 embryos (53.6 ± 7.8% vs. 35.9 ± 10.2%; P < 0.05). The results suggest that the success of the MOET trials was influenced by the transfer of embryos at the late morula stage, almost half of which were classified as grade 2 embryos. These findings highlight the importance of following strict embryo quality grading criteria to inform the most economical management of recipient ewes and maximize pregnancy outcomes.

Towards Improving the Outcomes of Multiple Ovulation and Embryo Transfer in Sheep, with Particular Focus on Donor Superovulation

Considerable improvements in sheep multiple ovulation and embryo transfer (MOET)protocols have been made; however, unlike for cattle, MOET is poorly developed in sheep, and thus has not been broadly applicable as a routine procedure. The tightly folded nature of the ewe cervix, the inconsistent ovarian response to various superovulatory treatments, and the requirement of labor to handle animals, particularly during large-scale production, has limited the implementation of successful MOET in sheep. Moreover, several extrinsic factors (e.g., sources, the purity of gonadotrophins and their administration) and intrinsic factors (e.g., breed, age, nutrition, reproductive status) severely limit the practicability of MOET in sheep and other domestic animals. In this review, we summarize the effects of different superovulatory protocols, and their respective ovarian responses, in terms of ovulation rate, and embryo recovery and transfer. Furthermore, various strategies, such as inhibin immunization, conventional superovulation protocols, and melatonin implants for improving the ovarian response, are discussed in detail. Other reproductive techniques and their relative advantages and disadvantages, such as artificial insemination (AI), and donor embryo recovery and transfer to the recipient through different procedures, which must be taken into consideration for achieving satisfactory results during any MOET program in sheep, are also summarized in this article.

A study of the factors affecting embryo yields and quality in superovulated Morada Nova ewes that underwent non-surgical uterine flushing

The present study compared the outcomes of in vivo embryo production in Morada Nova ewes subjected to either 9-day (G-9_SOV , n=21) or 12-day (G-12_SOV , n=21) progesterone (P₄ )-based estrus synchronization protocol coupled with superovulatory treatment with decreasing doses of porcine follicle-stimulating hormone (133 mg of pFSH given over 3 days). Non-surgical embryo recovery (NSER) was performed 6-7 days after the onset of estrus. Total antral follicle count doubled from the 1^st to the 6^th pFSH dose in both groups (P < 0.05). Estrus responses did not vary between the two groups of animals (95.2%). Corpora lutea (CL) were detected in 85.0% and 60.0% of ewes that previously manifested estrus behavior in G-9_SOV and G-12_SOV , respectively. NSER was successfully completed in 86.2% of ewes that had CL (P > 0.05). The mean number of CL per ewe/successfully flushed donor ewe was greater (P < 0.05) in G-12_SOV (12.3 ± 1.7/12.1 ± 1.9) than in G-9_SOV (7.9 ± 1.4/8.2 ± 1.6). Mean numbers of retrieved blastocysts and viable embryos were greater (P > 0.05) in G-12_SOV (5.8 ± 1.9 and 3.7 ± 1.7) than G-9_SOV (3.5 ± 1.1 and 0.8 ± 0.3, respectively). The total follicle count (all follicles ≥ 2 mm in diameter) at the 6^th pFSH dose (at P₄ -device removal) was positively correlated (P < 0.05) with the number of CL (r = 0.95) and viable embryos (r = 0.91) in G-12_SOV . The ewes with ≥ 10 CL (48% of all flushed donors) yielded 80.5% of viable embryos. In summary: i. Morada Nova ewes from G-12_SOV group had better superovulatory responses compared with G-9_SOV group; ii. total follicle count at the last pFSH dose was a good predictor of superovulatory responses only in the ewes primed with P₄ for 12 days; and iii. animals with ≥ 10 ovulations are main contributors to viable embryo production in Morada Nova ewes.

Intrafollicular oocyte transfer (IFOT): Potential feasibility in the ovine species

Intra-follicular oocyte transfer (IFOT) is a promising and innovative technique for in vivo embryo production previously described for equines and bovines. The aim of this study was to assess the feasibility of IFOT in the ovine species. Two preliminary in vivo and in vitro trials were performed to test the optimal procedures and timing for IFOT. In the in vivo trial, follicular growth was monitored with transrectal ultrasonography in ten adult ewes to preliminarily determine the ovulation and ideal timing for IFOT. The in vitro trial assessed i) the optimal inner diameter of the injection needle and ii) the recovery rate and integrity of injected cumulus-oocyte complexes (COCs) after follicle aspiration. For IFOT and embryo collection, five ewes were synchronized by CIDR insertion. Forty hours after CIDR removal, in ewes under sedation and general anesthesia, the ovaries were exposed by laparotomy, and the preovulatory follicle was injected with COCs previously collected from ovaries obtained from an abattoir. At 4 h after surgery, fully recovered ewes were housed in a paddock with a ram of proven fertility. Crayon marking on ram's chest was used to detect mating. Ovulation was assessed 40 h after the transfer of oocytes by transrectal ultrasonography. On day 6 after IFOT, embryo collection was performed by uterine flushing. In the in vitro testing, injection of >5 mm follicles with a 28 G needle loaded with 30 COCs in a 5 μL volume resulted in higher recovery rates and better preservation of COCs integrity. In the in vivo trial, ultrasound scanning revealed that ovulation occurred between 60 and 72 h after CIDR removal in all animals. In one ewe subjected to IFOT, 22/24 oocytes were effectively injected into the preovulatory follicle, but no embryos were collected after flushing. In the remaining four animals, 85/102 oocytes were injected, and six cleaved embryos, 12 morulae and 1 blastocyst were collected, including native embryos. This preliminary investigation indicated that IFOT in ovine species resulted in ovulation, fimbrial capture, tubal transport of heterologous oocytes and in vivo embryo production. Further studies are needed to optimize the embryo recovery rate and develop less invasive techniques for oocyte injection and uterine flushing, such as through a laparoscopic or transcervical approach.

Relationship between superovulation and embryo production with ovarian follicular population before superovulatory treatment in Brazilian Bergamasca sheep

ABSTRACT The objective of this study was to quantify the superovulatory response and embryo production of Brazilian Bergamasca sheep and to evaluate the link to the follicular condition before superovulatory treatment, as a reference for selection of donors with potential for superovulation. Follicular population of twenty-three sheep was evaluated by ultrasound during metestrus phase of the estrous cycle and divided into groups of low, medium and high follicular population. Subsequently, they were synchronized, superovulated with 133mg of pFSH, mated and subjected to embryo collection. The superovulatory response (9.0±3.3 vs 10.7±6.2 vs 13.8±7.1) and embryo production (4.0±3.8 vs 2.6±2.0 vs 1,8±4.0) were similar between groups (P>0.05). There was a positive correlation between the number of follicles during the metestrus phase and the number of corpus luteum with premature regression (PLR) (0.52) and a negative correlation between the recovery rate and PLR (-0.44) (P<0.05). The sheep that presented PLR had more follicles during metestrus (16.9±7.8 vs 12.7±3.2) and lower embryo recovery rate (38.8±29.3 vs 72.2±29.9) than those with functional CLs (P<0.05). Follicular quantification during metestrus phases was unable to identify donors with high embryo production. Animals with PLR had a larger follicular population during metestrus and lower embryo recovery rate.

Synchronization of follicular wave emergence does not improve embryonic yield in superovulated ewes

The present study aimed to investigate the effects of a combination of progesterone with different doses of E-17β on following end points: (1) ovarian follicular dynamics and emergence of a new follicular wave, and (2) superovulatory response and embryo yield. In Experiment 1, 28 ewes were randomly divided into four groups (n = 7) to receive either 2.0 mg, 1.0 mg, 0.5 mg or none E-17β one day after insertion of a progesterone device. The different doses of estradiol similarly delayed the moment of follicular emergence (overall mean = 3.1 ± 1.0 days vs. control group = 0.86 ± 1.0 days; P < 0.01), but the emergence of the new wave showed greater synchronization with the 0.5 mg dosage of E-17β. In Experiment 2, sixty-two donor ewes received an internal progesterone release device (day -1) for 7 d and 1 d after the insertion of this device (day 0) were allocated randomly to receive 0.5 mg of E-17β or only the vehicle (control group). Superstimulation was initiated on day 3 with the administration of 133 mg of pFSH in eight decreasing doses. Contrary to expectations, the protocol with the administration of 0.5 mg E-17β did not improve the percentage of donors with > 2 CL, the number of CL and the production of embryos (P > 0.05). It was concluded that the combination of progesterone and 0.5 mg E-17β was more efficient in synchronizing the emergence of the new follicular wave, however this approach seems to be unnecessary in ewe’s superovulation programs.

The Effect of P4 + eCG Estrus Induction Protocol during the Deep and the Transition Anestrous Period on the Reproductive Performance of Crossbred Dairy Goats

Simple Summary

The effect of an ultra-short progesterone (P4) plus equine chorionic gonadotropin (eCG) based estrus induction protocol during deep seasonal anestrous, or the reproductive transition period upon reproductive performance in an arid environment (26° N) was assessed. Results confirm a multidimensional response of goats regarding the effectiveness of P4 + eCG estrus induction protocols, mainly modulated by a specific time within the anestrous season (June) or even by specific management or a particular environment at herd level (herd 1 in this study), although, it is quite remarkably non–dependent on the animal’s body weight or body condition score.

Abstract

Seasonal reproduction restricts the offering of goat commodities across the year. Therefore, it is crucial to improve diverse strategies to induce the reproductive response in goats during the anestrus stage. The effectiveness of a short P4 + eCG-based estrus induction protocol during both the deep anestrous (March) or the reproductive transition period (June) upon the reproductive performance of crossbred dairy goats was assessed. Adult, anestrous, 24–30-month- old dairy crossbred (Saanen–Alpine–Nubian × Criollo) goats (n = 123) from two commercial herds and 10 sexually active goat bucks were used. Before the trials, the anestrous status of goats was confirmed. Then, goats were randomly allocated into two different experiments. In Exp. 1, we tested the effect of different doses (D) of intramuscular progesterone (P4; 10 or 20 mg + eCG (100 UI)) and type of breeding (TB), natural mating (NM), or artificial insemination (AI), on two commercial goat herds (H1 & H2), in March (deep anestrous). In Exp. 2, we evaluated the effect of D (P4; 10 or 20 mg + 100 UI eCG) in goats subjected to NM, and either during deep anestrous (March; M) or transitional anestrous (June; J), in two commercial herds. After breeding, conception and pregnancy were diagnosed with ultrasound scanning. The response variables were estrus induction (EI; %), estrus latency (EL; h), ovulation (OVP; %), ovulation rate (OR; units), fertility (FERT; %), and pregnancy (PREG; %). No differences (p > 0.05) in live weight (LW) and body condition score (BCS) occurred between herds in both trials. In Exp. 1, EI, EL, OVP, OR, FERT, and PREG were affected (p < 0.05) by the H–TB–D interaction, whereas in H1 + P4–20 combination had the highest (p < 0.05) EI, EL, and OVP values. Irrespective of TB, H1 had the largest (p < 0.05) OR, independently of TB or D. Also, the lowest (p < 0.05) OVP occurred in the AI + P4–10 group, while the AI had the lowest (p < 0.05) FERT, irrespective of D. FERT and PREG were two-fold higher (p < 0.05) in NM compared with AI. In Exp. 2, EI, EL, OVP, OR, FERT, and PREG were affected (p < 0.05) by the H–M–D interaction. In general, H2 + P4–10 had the lowest (p < 0.05) reproductive outcomes in March, whereas H1 had the largest (p < 0.05) values in either month. No differences (p > 0.05) between P4 doses occurred for EI, OVP, OR, FERT, and PREG. Yet, the largest (p < 0.05) EL occurred with P4–20 in June. No correlations (p > 0.05) occurred between LW and all the reproductive variables. BCS was positively correlated (p < 0.05) with EI (0.34), OVP (0.44), OR (0.58), and PREG (0.20). Also, positive correlations (p < 0.05) occurred between EI with EL (0.83), OVP (0.80), OR (0.64), and PREG (0.56); EL with OVP (0.58), OR (0.44), and PREG (0.42); OVP with OR (0.79) and PREG (0.70), as well as OR and PREG (0.63). Results of these studies confirm a multidimensional response regarding the effectiveness of P4 + eCG for estrus induction in goats mainly modulated by a specific time within the anestrous season, or even by specific management or a particular environment at the herd level (H1), although quite remarkably independent of the animal’s LW or BCS at herd level. Moreover, the best reproductive outcomes occurred with NM in June. The most reproductive variables were similar using either 10 or 20 mg P4 + 100 IU eCG, giving the possibility to lessen the scale in the use of exogenous hormones while obtaining acceptable out of season reproductive response.

Embryo yield and quality are associated with progestogen treatment during superovulation protocol in lactating Lacaune ewes

This study assessed the effect of progestogen treatment length on ovarian parameters and embryo yield in superovulated Lacaune ewes collected by nonsurgical embryo recovery. Twenty-three lactating ewes were superovulated 30 d apart using a cross-over design. All ewes received 60 mg of MAP intravaginal sponges for 6 (G-6 group) or 9 (G-9 group) d. A total dose of 133 mg pFSH was given in six decreasing doses (twice a day) starting at 60 h before device removal. Ultrasound examination of the ovaries was performed at the first pFSH injection and one day before embryo recovery, which was performed 6-7 d after the onset of estrus. Embryo recovery was conducted only in ewes that expressed estrus and were mated. There was no difference (P > 0.05) in the total number of follicles between G-6 (15.7 ± 1.0) and G-9 (15.6 ± 0.8) at the time of the first pFSH treatment. The percentage of responding donors with ≥3 corpora lutea (CL; 78.2% [18/23] vs 69.5% [16/23]), mean (±SEM) CL number (7.0 ± 1.2 vs 8.1 ± 1.6), transcervical passage rate (94.4% [17/18] vs 83.3% [15/18], and ova/embryo recovery rate (54.5% [60/110] vs 68.0% [83/122]) were not different (P > 0.05) between the G-6 and G-9 groups. However, the mean number of viable embryos was lower (P < 0.05) in the G-6 group (1.8 ± 0.7) than in the G-9 group. (3.5 ± 1.1). In conclusion, treatment with an intravaginal MAP sponge for 9 d during a superovulation protocol is beneficial for viable embryo yield in Lacaune ewes out of the breeding season.

Repeated trans-cervical embryo recoveries in Santa inês ewes subjected to short- or long-term superovulatory treatment regimens

Outcomes of short- (6.5 days) and long-term (14.5 days) estrous synchronization for 6.5 d (G-6.5d) or 14.5 d (G-14.5d) and followed by the 4-day or 3-day declining-dose follicle-stimulating hormone superovulatory regimen, respectively, were compared using 16 estrous-cycling Santa Inês ewes. Non-surgical embryo recovery (NSER) procedures were performed 60 d apart starting 6 or 7 d after the onset of estrus; an i.m. injection of estradiol benzoate and of d-cloprostenol at 16 h was followed by an i.v. oxytocin injection administered 20 min before NSER. There was a longer (P < 0.05) period before estrous onset in ewes during the second (September) compared with the first study replicate (July) by approximately 14 h. The NSER could be performed in 11 of 15 ewes that were in estrus, with an average of three viable-embryos/donor and the mean duration of the procedure being 29 min. There were no differences in superovulatory responses between the two groups of ewes, but there were only degenerated embryos in ewes of the G-6.5d group. In summary: i. the duration of progestin-priming and of multiple-dose pFSH treatment had a limited effect on superovulatory responses in estrous-cycling Santa Inês ewes; ii. NSER is a safe and repeatable method of embryo collection in ewes subsequent to superovulation; and iii. duration of the superovulatory treatment regimen may alter the effects of endogenous steroids on oocyte/embryo quality in ewes.

Towards Improving the Outcomes of Assisted Reproductive Technologies of Cattle and Sheep, with Particular Focus on Recipient Management

The Australian agricultural industry contributes AUD 47 billion to the Australian economy, and Australia is the world's largest exporter of sheep meat and the third largest for beef. Within Australia, sheep meat consumption continues to rise, with beef consumption being amongst the highest in the world; therefore, efficient strategies to increase herd/flock size are integral to the success of these industries. Reproductive management is crucial to increasing the efficiency of Australian breeding programs. The use of assisted reproductive technologies (ARTs) has the potential to increase efficiency significantly. The implementation of multiple ovulation and embryo transfer (MOET) and juvenile in vitro fertilization and embryo transfer (JIVET) in combination with genomic selection and natural mating and AI is the most efficient way to increase genetic gain, and thus increase reproductive efficiency within the Australian livestock industries. However, ARTs are costly, and high variation, particularly between embryo transfer recipients in their ability to maintain pregnancy, is a significant constraint to the widespread commercial adoption of ARTs. The use of a phenotypic marker for the selection of recipients, as well as the better management of recipient animals, may be an efficient and cost-effective means to increase the productivity of the Australian livestock industry.

Are the spectral Doppler indices of ovarian arteries indicative of antral follicular development and predictive of ovulatory responses and embryo yields in superovulated ewes?

Nineteen ewes received 200 mg of pFSH administered in eight decreasing doses from Days 1 to 4, starting three days before CIDR® device removal. Ten ewes received an injection of 350 μg of estradiol benzoate at CIDR® device insertion (Group E) and nine animals served as controls (Group C). B-mode and spectral Doppler ultrasonographic examinations were performed daily throughout superovulatory treatment to enumerate ovarian antral follicles and to determine ovarian blood flow indices, respectively. There were no differences (P > 0.05) in superovulatory responses between left and right ovaries/uterine horns or the two groups of animals. End-diastolic velocity (EDV) and mean velocity (Vm) values were greater (P < 0.05) on Days 1 and 2, and peak systolic velocity (SVp) was greater (P < 0.05) on Day 3 in Group C than in Group E. In Group E 15 correlations was recorded among indices (SVp, Vm, EDV, flow velocity integral-FVI, and pulsatility index-PI) and follicles numbers in different size classes on Days 1, 2 and 4, and seven correlations among indices (SVp, EDV, Vm, and vascular resistance index-RI) and superovulatory/embryo results (numbers of regressing corpora lutea, numbers/percentages of degenerated embryos and viability rates) on Days 1, 2 and 3. In Group C, there were three correlations among EDV and RI and medium-sized/large follicle numbers on Days 1 and 3, and five correlations among indices (EDV, RI and PI) and superovulatory/embryo results (numbers of luteinized unovulated follicles, degenerated embryos and unfertilized eggs) on Days 2 or 4. There was a lack of consistency in the velocimetric correlates of antral follicle numbers and superovulatory responses between the left and right side. Therefore, the usefulness of ovarian arterial indices to predict ovine superovulatory outcomes remains equivocal and requires further confirmatory studies.

Follicular dynamics and in vivo embryo production in Santa Inês ewes treated with smaller doses of pFSH

To evaluate follicular dynamics, there was assessment of superovulatory response and in vivo embryo production in ewes treated with relatively smaller doses of exogenous pFSH than typically used in combination with a dose of eCG at the beginning of the gonadotropin treatment period. Santa Inês ewes (n = 24) were randomly divided into three groups, based on mg dose of pFSH administered: G200 (n = 8), G133 (n = 8) and G100 (n = 8) in eight decreasing doses at 12 -h intervals. All ewes were treated with 300 IU of eCG concomitantly starting with first pFSH administration. Ovulatory follicular dynamics and follicular wall vascularization (FWV) were evaluated using a B-mode and color Doppler ultrasonic machine, respectively. Superovulatory response and embryo production were evaluated 6 days after estrous detection. In the G200 group, the preovulatory follicle size (PFS) were less (P <  0.05), ovulation time later (P <  0.05), and PFS rate greater (P <  0.05); while in the G100 group ovulation rate, and number and percentage of unfertilized eggs were greater (P <  0.05) than in the G133 group (P <  0.05). Number and percentage of viable embryos were greater in the G200 and G100 compared to G133 group (P <  0.05). The dose of 100 mg of FSH was as efficacious as the traditional dose of 200 mg, in combination with a dose of eCG, for superovulatory response and viable embryo production but there was a greater percentage of unfertilized eggs with this treatment.

Evaluation of morphology, morphometry and follicular dynamics in FecGE genotyped ewes

This study aimed to evaluate the effect of FecG^E mutation on the development of ovarian follicles. To this end, 42 Santa Inês ewes were genotyped for FecG^E mutation and classified as wild-type (FecG^+/+), heterozygous (FecG^+/E) or mutant homozygous (FecG^E/E). Ovarian fragments were processed, and the follicles were analyzed with regard to the morphology and morphometry using classical histology. For the evaluation of follicular dynamics, ewes underwent oestrous synchronization and were monitored throughout an interovulatory period. A higher (P < 0.05) percentage of morphologically normal follicles in the primordial stage was identified in FecG^E/E (90.0%) and FecG^+/E (88.1%) ewes than in the FecG^+/+ (73.0%) ewes. There was also a significantly greater (P < 0.05) number of morphologically normal follicles in the FecG^E/E (87.3%) and FecG^+/E (83.3%) ewes than in FecG^+/+ (76.8%) ewes in the transitional stage. A smaller (P < 0.05) diameter was observed in the secondary follicles in FecG^E/E (93.8 μm) ewes than in FecG^+/E (171.8 μm) ewes. Regarding follicular dynamics, FecG^E/E ewes showed a greater (P < 0.05) number of ovulations (2.5 ± 0.2) than FecG^+/+ ewes (1.5 ± 0.3) ewes. Ovulatory follicles were smaller (P < 0.05) in the FecG^E/E (5.1 mm) and FecG^+/E (5.2 mm) ewes than in FecG^+/+ (5.8 mm) ewes. Santa Inês nulliparous ewes carrying the FecG^E mutation showed a greater proportion of morphologically normal follicles in the primordial and transitional stages than those not carrying the mutation. FecG^E/E ewes demonstrated a higher number of ovulated follicles and that FecG^E/E and FecG^+/E ewes presented ovulatory follicles with a smaller diameter.

Non-surgical embryo transfer in goats and sheep: the Brazilian experience

Brazil has presented tremendous progress in non-surgical embryo transfer (NSET) in sheep and goats. New instruments and techniques for non-surgical embryo recovery (NSER) and NSET in small ruminants were implemented. Recent improvements include refinement of the protocols for cervical relaxation combining oestradiol–oxytocin–cloprostenol treatment at specific times before NSER in sheep; recipient goats do not require any hormonal drugs to induce cervical dilation and direct embryo transfer by the cervical route yields excellent results. Transrectal ovarian ultrasonography (B-mode but especially colour Doppler) have proven to be accurate methods to localise and enumerate corpora lutea and luteinised unovulated follicles in recipient and donor does and ewes. An array of new criteria for selecting superior animals for NSER and NSET (e.g. cervical mapping) have been developed by Brazilian researchers. Extensive studies on both technologies were initially conducted in commercial breeds of goats and sheep but have been gradually extended to some native breeds of sheep (germplasm conservation) and dairy goat operations. It is speculated that, in future, NSER and NSET may become methods of choice for caprine and ovine embryo recovery and transfer in Brazil, and then globally. Due primarily to the efficiency of NSET in goats, a novel interspecies (e.g. bovine) IVP method may soon be developed on a large scale. The Brazilian experience is an invaluable source of information and know-how promoting the replacement of conventional surgical assisted reproductive technologies with non-surgical procedures and hence supporting the rapid development of the embryo transfer industry in small ruminants.

Anti-Müllerian hormone and antral follicle count are more effective for selecting ewes with good potential for in vivo embryo production than the presence of FecGE mutation or eCG pre-selection tests

This study aims to compare four different methods for selecting high responding sheep donors for in vivo embryo production. These methods include a pre-selection eCG test (eCG), antral follicle count (AFC), plasma anti-Müllerian hormone measurement (AMH) and genotyping for the presence of the FecG^E mutation (a polymorphism in the GDF9 gene associated with increased ovulation rate). Santa Ines ewe lambs (n = 25) underwent superovulation (SOV) with 800 IU equine chorionic gonadotropin (eCG) and the corpus luteum (CL) count was recorded by laparoscopy after eight days. At the D0_eCG, blood samples for AMH and genotyping analysis were collected. Twenty-one days after the end of the eCG test, the same animals underwent SOV with 200 mg of FSH, administered in six decreasing doses, and then naturally mated. Immediately before the beginning of the FSH protocol (D0_FSH), and at the moment of the first FSH dose (D9_FSH), the AFC was assessed. Plasma AMH was again determined at the D9_FSH. After each screening process, animals were classified as having a high (HR), or low (LR), potential of response (using specific thresholds for each method). Then, the ewes' response to SOV and embryo yield for each screening method, classified as HR or LR, were compared. Animals classified as HR by AFC (HR_AFC) and by AMH concentration (HR_AMH) at the D9_FSH, produced more viable embryos than those classified as LR_AFC and LR_AMH (HR_AFC 6.2 ± 3.2 vs LR_AFC 2.8 ± 3.0 and HR_AMH 6.6 ± 3.6 vs LR_AMH 3.0 ± 2.9). Pre-selection tests with eCG and different FecG^E genotypes, either heterozygous (+/E) or wild type (+/+), were unable to discriminate HR or LR animals. A tendency (P = 0.06) to have lower plasma AMH was observed in heterozygous FecG^E (+/E) ewes. In conclusion, both AFC and plasma AMH can be used to select donor ewes with a higher potential of response for in vivo embryo production.