Multiple Ovulation Research Articles

Recipient maternal genotypes improved the litter size components of a paternal line involved in a MOET programme in rabbits

An essential factor in the success of multiple ovulation and embryo transfer programmes (MOET) in any species is the selection of the recipient females. In rabbit there is a notable lack of studies on the effects of recipient genotype on postnatal growth. The aim of this study was to evaluate the effects of recipient maternal genotypes on litter size components within a MOET programme applied to a commercial paternal line that appears to have exhausted its selection programme after 37 generations. The experiment was designed using 13 nulliparous donors from the R line (paternal line) to produce 453 embryos, which were transferred to two recipient maternal genotypes (A and V lines) and the own donor paternal line (R line). Litter size components and pre-and postnatal body mass of kits were evaluated. The differences between the genetic groups of recipients were estimated using a general linear model applying Bayesian analysis. The results showed that maternal lines have a high capacity to implant the embryos, maintain the pregnancy and present a favourable environment for embryo development compared to the R line. Specifically, A line dams showed the highest prenatal survival, total born and number born alive without effects on growth traits. The present study demonstrated the applicability of a MOET programme based on maternal ability recipients to improve the number of kits per cycle. Therefore, to allow the genetic improvement programme of meat rabbits to continue using the R line, we recommended applying for a MOET programme as a routine procedure. HIGHLIGHTS MOET programme based on maternal ability recipients enhanced the number of kits per cycle. The MOET programme could be a routine procedure to favour the selection of paternal lines by increasing selection pressure.

A simple method to select high superovulatory responder goats

In most female mammals, a common drawback to multiple ovulation embryo transfer programs is the variability in the superovulatory response to the multidose pFSH treatment. The aim of the present study was to identify embryo donor goats based on their response to superovulation before the performance of a high-cost hormonal treatment, as we have previously done in sheep. To this end, we evaluated the number of ovulations obtained in response to the administration of a one-shot eCG treatment and related it with the subsequent ovarian response to a multiple-dose pFSH treatment in 33 goats of the Criolla-Neuquina breed. Goats received a one-shot eCG treatment of 800 IU at the end of a 17-day progestational treatment; 9 days later, started a second 17-day progestational treatment and then received a multiple-dose pFSH treatment on days 15–17 (116 mg pFSH, in six decreasing doses). The number of corpora lutea (CL) per goat was recorded laparoscopically after both hormonal treatments. On day 8 after the second pessary removal, embryos were surgically recovered and classified by quality. Results showed a significant positive correlation between the number of CL obtained in response to the eCG and pFSH treatments (r = 0.41; y = 0.8352x + 6.9906; P < 0.05), although of limited value to select high ovulatory responding goats, due to its low correlation value. Then, goats were grouped into high and low ovulatory responders to the eCG (High ≥9; Low <9 CL) and pFSH treatments (High ≥13; Low <13 CL). After the eCG and pFSH treatments, 60% of the goats maintained their classification as high or low superovulatory responders (expressed as recurrence rate). Significant differences were found in the number of CL (18.2 ± 1.3 vs 9.9 ± 1.3), number of embryos + oocytes (13.5 ± 1.7 vs 7.6 ± 1.7), number of embryos (10.8 ± 1.4 vs 5.1 ± 1.4) and number of Grade 1 and Grade 2 embryos (8.8 ± 1.4 vs 4.3 ± 1.4) between high and low superovulatory responder goats (P < 0.05), while no differences were observed in the number of oocytes and in the recovery of embryos + oocytes, embryos, Grade 1 and Grade 2 embryos and fertilization rates (P > 0.05). In conclusion, the recurrence rate in ovarian response between the one-shot eCG treatment and the multiple-dose pFSH treatment would confirm the existence of an “individual or intrinsic factor” of the donor goat that would respond as a high or low ovulatory responder to superovulatory treatments.

EP46.12: Multiple ovulations: the sign on the borderland of primary ovarian insufficiency and fertility stimulation treatment effects

EP46.12: Multiple ovulations: the sign on the borderland of primary ovarian insufficiency and fertility stimulation treatment effects

Ovule initiation: the essential step controlling offspring number in Arabidopsis

AbstractSeed is the offspring of angiosperms. Plants produce large numbers of seeds to ensure effective reproduction and survival in varying environments. Ovule is a fundamentally important organ and is the precursor of the seed. In Arabidopsis and other plants characterized by multi‐ovulate ovaries, ovule initiation determines the maximal ovule number, thus greatly affecting seed number per fruit and seed yield. Investigating the regulatory mechanism of ovule initiation has both scientific and economic significance. However, the genetic and molecular basis underlying ovule initiation remains unclear due to technological limitations. Very recently, rules governing the multiple ovules initiation from one placenta have been identified, the individual functions and crosstalk of phytohormones in regulating ovule initiation have been further characterized, and new regulators of ovule boundary are reported, therefore expanding the understanding of this field. In this review, we present an overview of current knowledge in ovule initiation and summarize the significance of ovule initiation in regulating the number of plant offspring, as well as raise insights for the future study in this field that provide potential routes for the improvement of crop yield.

Correlation analysis of serum reproductive hormones and metabolites during multiple ovulation in sheep

BackgroundThe establishment of non-invasive diagnostic method for multiple ovulation prediction is helpful to improve the efficiency of multiple ovulation. The blood hormones and metabolites would be suitable indexes for this subject.MethodsIn this study, 86 estrus ewes (65 of induced estrus (IE) and 21 of spontaneous estrus (SE)) were selected and the blood samples were collected at the day before follicle-stimulating hormone (FSH) injection (1st) and before artificial insemination (2nd). The serum reproductive hormones ofFSH, luteinizing hormone (LH), 17β-Estradiol (E2), progesterone (P4) and anti-Mullerian hormone (AMH) were measured through enzyme linked immunosorbent assay (ELISA) and the untargeted metabolomics analysis was processed through LC–MS/MS. The embryos were collected after 6.5 days of artificial insemination.ResultsIn total, 975 and 406 embryos were collected in IE and SE group, respectively. The analysis of reproductive hormones showed that concentrations of FSH, E2 and AMH were positive correlated with the embryo yield while concentrations of LH and P4 were negative correlated in both group at 1st detection. At 2nd detection, the trends of reproductive hormones were similar with 1st except P4, which was positive correlated with embryo yield. The metabolomics analysis showed that 1158 metabolites (721 in positive iron mode and 437 in negative iron mode) were detected and 617 were annotated. In 1st comparation of high and low embryonic yield populations, 56 and 53 differential metabolites were identified in IE and SE group, respectively. The phosphatidyl choline (PC) (19:0/20:5) and PC (18:2/18:3) were shared in two groups. In 2nd comparation, 48 and 49 differential metabolites were identified in IE and SE group, respectively. The PC (18:1/18:2) and pentadecanoic acid were shared. Most differential metabolites were significantly enriched in amino acid, fatty acid metabolism, digestive system secretion and ovarian steroidogenesis pathways.ConclusionsThis study showed that FSH, P4, AMH, the PC relevant metabolites and some anomic acids could be potential biomarkers for embryonic yield prediction in ovine multiple ovulation. The results would help to explain the relation between blood material and ovarian function and provide a theoretical basis for the multiple ovulation prediction.

Mixed-Effects Modelling of the Risk Factors Associated with Multiple Pregnancies in Thoroughbred Mares.

Simple SummaryMultiple pregnancies (MPs), or twins/triplets, are commonly diagnosed in pregnant mares. Whilst some studies have identified factors associated with an increased risk of MPs, they have only looked at each factor individually and not accounted for the effects of factors when they occur together. This study used statistical modelling to identify risk factors for MPs, looking at 27 factors as well as the contribution of the mare, stallion (both proxies for genetics), farm, and veterinarian. We found that multiple ovulations and the use of a drug that mimics prostaglandin F2α to induce oestrus, both increased the risk of a mare having an MP. Mares that had a foal that same year, had a uterine cyst, or who did not get pregnant on the first cycle they were bred on were at a decreased risk of having an MP. Factors that impact the early embryonic environment are more important influences of multiple pregnancies when compared to the genetics of the mare. The increased incidence of MP but not MOs over the previous decades may well reflect improved management of the endometrium as opposed to selection of mares with increased risk for MPs. A limitation of the study is the reliance on clinical records being completed accurately.Multiple pregnancies (MPs) are commonly diagnosed during breeding management of mares. Whilst some studies have reported on factors associated with the risk of MPs, few have utilised multivariable data analysis to control for confounding variables. A prospective cohort study of Thoroughbred broodmares was conducted with information collected on 27 factors. Mixed-effects logistic regression was used to determine risk factors for MPs. Mare, stallion, stud, and veterinarian were evaluated as random effects. The prevalence of MPs in 1754 mares and 2245 pregnancies was 16.06% (95% confidence interval [CI] = 14.54, 17.58). Multiple ovulations (OR = 15.57, 95% CI = 11.88, 20.53) and treatment with cloprostenol (OR = 1.35, 95% CI = 1.015, 1.80) were associated with increased odds of MPs following multivariable analysis. Mares that foaled at the start of the breeding season (OR = 0.66, 95% CI = 0.47, 0.94), conceived at the second or more oestrus cycles (OR = 0.60, 95% CI= 0.43, 0.84), or identified with a uterine cyst (OR = 0.63, 95% CI = 0.40, 0.97) were at reduced odds of conceiving MPs. Mare, stallion, stud, and veterinarian were not associated with MPs. These findings provide possible explanations as to why the prevalence of MPs but not MOs have increased over the last decade.

Luteal Tissue Area and Immunoreactive Concentration of Progesterone in Plasma of Bred and Non-bred Mares

Progesterone is pivotal to maintain pregnancy in the first trimester and low concentration (<4 ng/mL) has been associated with early pregnancy loss. Measurement of progesterone is widely used in practice to determine whether a mare needs progestin supplementation. Therefore, the objective of the present study was to determine progesterone concentration and the luteal tissue area in mares non-bred, and those bred becoming pregnant, and those failing to become pregnant. We hypothesized that pregnant mares have greater progesterone concentration than non-pregnant mares. Fifty-two cycles of mares (n = 14) were monitored by ultrasonography every other day until detection of a pre-ovulatory follicle. Then deslorelin acetate was administered to induce ovulation. Twenty-four hours later, mares were bred (∼2 billion progressively motile sperm extended in 50 mL; n = 37 cycles) or a sham-bred (50 mL of extender; n = 15 cycles). Ovulation was confirmed and number of corpora lutea and the luteal tissue area were recorded daily until 10-days post-ovulation. Progesterone concentration was assessed daily from the day of the ovulation up to 10-days post-ovulation. Pregnancy diagnosis was carried out at 10- and 13-days post-ovulation. Of the bred mares, 20 of them became pregnant and 17 did not. Data were analyzed with a mixed model, Tukey's test as post-hoc, and Pearson's coefficient of correlation. Progesterone concentration and luteal tissue area varied with time (P = .001) but not with group (P > .05). Multiple ovulations were associated with greater progesterone concentration and luteal tissue area (P = .0001). There was a moderate positive association between the number of ovulations and luteal tissue area (r = 0.54; P = .0001). The lack of change in the progesterone concentration and luteal tissue area between bred and non-bred mares suggests that horse seminal plasma does not affect luteal function in mares. As all mares had progesterone above 4 ng/mL after 5-days post-ovulation; it is possible that if mares with abnormal progesterone concentration were used, the results could have been different. In conclusion, pregnancy was not associated with greater progesterone concentration or luteal tissue area.

Effect of elevating luteinizing hormone action using low doses of human chorionic gonadotropin on double ovulation, follicle dynamics, and circulating follicle-stimulating hormone in lactating dairy cows

Double ovulation and twin pregnancy are undesirable traits in dairy cattle. Based on previous physiological observations, we tested the hypothesis that increased LH action [low-dose human chorionic gonadotropin (hCG)] before the expected time of diameter deviation would change circulating FSH concentrations, maximum size of the second largest (F2) and third largest (F3) follicles, and frequency of multiple ovulations in lactating dairy cows with minimal progesterone (P4) concentrations. In replicate 1, multiparous, nonbred lactating Holstein dairy cows (n = 18) had ovulation synchronized. On d 5 after ovulation, all cows had their corpus luteum regressed and were submitted to follicle (≥3 mm) aspiration 24 h later to induce emergence of a new follicular wave. Cows were then randomized to NoP4 (untreated) and NoP4+hCG (100 IU of hCG every 24 h for 4 d after follicle aspiration). Ultrasound evaluations and blood sample collections were performed every 12 h for 7 d after follicle aspiration. All cows were then treated with 200 μg of GnRH to induce ovulation. In replicate 2, cows (n = 16) were resubmitted to similar procedures (i.e., corpus luteum regression, follicle aspiration, randomization, ultrasound evaluations every 12 h, GnRH 7 d after aspiration). However, cows in replicate 2 received an intravaginal P4 device that had been previously used (∼18 d). Only cows with single (n = 15) and double (n = 16) ovulations were used in the analysis. No significant differences were detected for frequency of double ovulation, follicle sizes, and FSH concentrations across replicates (NoP4 vs. LowP4 and NoP4+hCG vs. LowP4+hCG), so data were combined. Double ovulation was 40% for control cows with no hCG (CONT) and 62.5% with hCG (hCG). Double ovulation increased as the maximum size of F2 increased: <9.5 mm and 9.5-11.5 mm (7.7%) and ≥11.5 mm (94.1%). The hCG group had more cows with F2 > 11.5 (69%) than with 9.5 ≥ F2 ≤ 11.5 (25%) and F2 < 9.5 (6%). In agreement, F2 and F3 maximum size were larger in the hCG group, but FSH concentrations were lower after F1 > 8.5 mm compared with CONT. In contrast, FSH concentrations were greater before deviation (F1 closest value to 8.5 mm) in cows with double ovulations than in those with single ovulations, regardless of hCG treatment. In addition, time from aspiration to deviation was shorter in cows with double rather than single ovulation and in cows treated with hCG as a result of faster F1, F2, and F3 growth rates before diameter deviation. In conclusion, greater FSH and follicle growth before deviation seems to be a primary driver of greater frequency of double ovulation in lactating cows with low circulating P4. Moreover, the increase in follicle growth before deviation and in the maximum size of F2 during hCG treatment suggests that increased LH may also have a role in stimulating double ovulation.

Novel roles of luteinizing hormone (LH) in tissue regeneration-associated functions in endometrial stem cells

Luteinizing hormone (LH) stimulates the synthesis and secretion of the key steroid hormone estrogen, which subsequently promotes ovarian follicular growth and development. Therefore, the administration of exogenous LH to achieve superovulation (multiple ovulations) and an LH surge is commonly used as the most effective therapeutic option in a majority of in vitro fertilization (IVF) clinics. However, a relatively low pregnancy rate (between 20% and 35%) is one of the most challenging aspects of LH-based infertility treatment. Furthermore, the major cause of this low pregnancy rate in LH-based infertility treatment remains unidentified. Recent studies have shown that endometrial stem cell loss or deficiency can significantly decrease tissue regeneration ability during the menstrual cycle and reduce endometrial receptivity. In this context, we postulated that the low pregnancy rates following LH-based ovarian hyperactivation may be the result of the adverse effects of consecutive exogenous LH administration on endometrial stem cells. To the best of our knowledge, this study revealed for the first time that in addition to its previously reported roles in stimulating ovarian functions through the pituitary-gonadal axis, LH brings about the extragonadal suppression of various tissue regeneration-associated functions in endometrial stem cells, such as self-renewal, migration ability, multilineage differentiation potential, and pluripotency/stemness, by inhibiting pro-survival Akt and ERK1/2 signaling pathways in vitro and in vivo, and as a consequence, it decreases the endometrial receptivity.

Bioactive supplements influencing bovine in vitro embryo development.

Ovum pickup and in vitro production (IVP) of bovine embryos are replacing traditional multiple ovulation embryo transfer (MOET) as the primary means for generating transferable embryos from genetically elite sires and dams. However, inefficiencies in the IVP process limit the opportunities to produce large numbers of transferable embryos. Also, the post-transfer competency of IVP embryos is inferior to embryos produced by artificial insemination or MOET. Numerous maternal, paternal, embryonic, and culture-related factors can have adverse effects on IVP success. This review will explore the various efforts made on describing how IVP embryo development and post-transfer competency may be improved by supplementing hormones, growth factors, cytokines, steroids and other bioactive factors found in the oviduct and uterus during early pregnancy. More than 40 of these factors, collectively termed as embryokines, are reviewed here. Several embryokines contain abilities to promote embryo development, including improving embryo survivability, improving blastomere cell numbers, and altering the distribution of blastomere cell types in blastocysts. A select few embryokines also can benefit pregnancy retention after IVP embryo transfer and improve neonatal calf health and performance, although very few embryokine-supplemented embryo transfer studies have been completed. Also, supplementing several embryokines at the same time holds promise for improving IVP embryo development and competency. However, more work is needed to explore the post-transfer consequences of adding these putative embryokines for any adverse outcomes, such as large offspring syndrome and poor postnatal health, and to specify the specific embryokine combinations that will best represent the ideal conditions found in the oviduct and uterus.

REVIEW ON THE IMPACT AND CONSEQUENCES OF THE OCCURRENCE OF MULTIPLE BIRTHS IN CATTLE AND GOATS

Background: The large animal species such as cattle, buffaloes and horses are monotocous with one or sometimes two newborns per birth whereas small farm animal species such as sheep, goats and pigs are usually polytocous animals are highly prolific and especially pigs often produce a dozen newborns at each farrowing. Cattle usually produce only one calf per gestation resulting from ovulation of a single follicle. The most common form of twinning in cattle occurs due to multiple ovulations which may produce dizygotic twins. The twin births in dairy cattle often negatively impacts the reproduction, production, health and reduces the productive lifespan of cows. Therefore, there is a great interest to know the multiple ovulations and multiple births to reduce the twinning rate in dairy cattle herds. Objective: This review updates the status of multiple births and its impact and consequences on production of dairy cattle and goats. Materials and Methods: The related literatures on the multiple births in cattle and goats have been reviewed for which the search was carried out in Google Scholar, PubMed, CrossRef, Banglajol and also the online daily newspapers. Results: Although multiple births with up to quadruplets have been reported from different countries, the prevalence of twin births are commonly reported in dairy cattle. The prevalence of twinning rates are varied widely in different breeds like twin calving in Holstein Friesian cattle is 3 to 5%, 5.6% Spanish dairy herd and 3.9% in Iranian Holsteins, whereas triplet and quadruplet births represent 0.015% and 0.004% of the total births, respectively. Twin calving shorten gestation length, increased dystocia, stillbirths, decrease birth weight, perinatal calf mortality, retained placenta, decrease milk production, increases the occurrence of metabolic diseases, reduced conception rate, increased calving interval, shorten the productive lifespan of the dam and increases overall culling rate. Two strategies- the transfer of a single embryo produced in vitro and follicular drainage of co-dominant follicles at AI have been suggested to prevent twin pregnancies. Conclusion: Multiple births in dairy cattle is not desirable due to negative effects on both cows that calve twins and calves born as twins that result in economic losses in dairy herds. Regardless of the direct effect of multiple births on health and fertility, reducing the occurrence of multiple ovulations to decrease the risk of twin births is desirable to mitigate the negative consequences of twinning in dairy cattle. The estimated losses due to twinning range between US$ 59 to 161 per twin pregnancy and attempting manual embryo reduction decreased the economic losses of a twin pregnancy by US $ 23 to 45. Bangladesh scientists discovered a new technique to produce twin calves but the future research on this aspect need to consider the negative effects of twin births in cattle.

In vitro- and in vivo-produced male dairy calves show molecular differences in the hepatic and muscular energy regulation†.

In cattle, the in vitro production (IVP) of embryos is becoming more relevant than embryos produced in vivo, i.e. after multiple ovulation and embryo transfer (MOET). However, the effects of IVP on the developmental programming of specific organs in the postnatal calves are yet unknown. Previously, we reported an epigenomic and transcriptomic profile of the hypothalamus–pituitary–testicular axis compatible with its earlier activation in IVP calves compared to MOET animals. Here, we studied the hepatic and muscular epigenome and transcriptome of those same male dairy calves (n = 4 per group). Tissue samples from liver and semitendinosus muscle were obtained at 3 months of age, and the extracted gDNA and RNA were sequenced through whole-genome bisulfite sequencing and RNA-sequencing, respectively. Next, bioinformatic analyses determined differentially methylated cytosines or differentially expressed genes [false discovery rate (FDR) < 0.05] for each Omic dataset; and nonparametrically combined genes (NPCG) for both integrated omics (P < 0.05). KEGG pathways enrichment analysis showed that NPCG upregulated in the liver and the muscle of the IVP calves were involved in oxidative phosphorylation and the tricarboxylic acid cycle. In contrast, ribosome and translation were upregulated in the liver but downregulated in the muscle of the IVP calves compared to the MOET calves (FDR < 0.05). A model considering the effect of the methylation levels and the group on the expression of all the genes involved in these pathways confirmed these findings. In conclusion, the multiomics data integration approach indicated an altered hepatic and muscular energy regulation in phenotypically normal IVP calves compared to MOET calves.

P-568 The effect of recombinant hCG on FSH-induced ovarian stimulation in rats depends on the FSH dose and can be detrimental at high concentrations

Abstract Study question What is the effect of choriogonadotropin beta (CG beta) on FSH-induced ovarian stimulation and multifollicular development in a rat model? Summary answer CG beta dose-dependently potentiates effects of low-to-mid FSH doses but has inhibitory effects at high concentrations: optimal CG beta/FSH ratio depends on the FSH dose. What is known already Similarly to follitropin delta (rFSH), CG beta (FE 999302) is a novel recombinant hCG purified from the human PER.C6®cell line. A recent placebo-controlled trial in women undergoing ovarian stimulation with follitropin delta demonstrated that the addition of 1 to 12 µg CG beta reduced the number of intermediate follicles and related hormones. This observation required further preclinical research to (1) evaluate whether the pharmacology of CG beta at LH/CGR was different than other hCG forms used in the clinic and/or (2) assess the effect of high concentrations of hCG and different hCG/FSH ratios on multiple follicular development and follicle atresia. Study design, size, duration Signaling properties of CG beta and other LH/hCG forms were compared at downstream pathways of LH/CGR in recombinant systems and human granulosa cells. To evaluate the effects of FSH±hCG in vivo, juvenile female rats were injected subcutaneously twice daily with follitropin delta ± CG beta/alfa for three days followed by an ovulatory dose of hCG. Oviducts were then collected for oocyte enumeration, ovaries and uteri were weighed, and ovaries were fixed for histological analysis. Participants/materials, setting, methods The pharmacology of CG beta and other LH/hCG forms was evaluated in a cAMP assay in human granulosa cells from follicular fluid from IVF patients and in recombinant systems, at the Gs, Gq and arrestin pathways. In the rat model, a dose response of follitropin delta (Rekovelle) was first evaluated, followed by evaluation of the dose-dependent effects of CG beta (0.00117-2.4 µg/kg), or CG alfa (Ovidrel/Ovitrelle), in combination with 1, 3 or 10 µg/kg rFSH. Main results and the role of chance The in vitro pharmacology (potency and efficacy) of CG beta was similar to recombinant LH, urinary hCG and recombinant hCG (CG alfa) tested at all proximal pathways evaluated downstream of LH/CGR as well as in human granulosa cells. In vivo, treatment with follitropin delta induced a bell-shaped dose-response curve for oocyte release with a maximum response of 40-50 oocytes at 8-10 µg/kg follitropin delta dose. The addition of CG beta dose-dependently potentiated the effects at low-to-mid follitropin delta doses but had inhibitory effects on the number of ovulated oocytes at high CG beta concentrations. The lowest CG beta dose that clearly reduced the number of ovulated oocytes was 2.4, 0.6 and 0.3 µg/kg in combination with a fixed dose of 1, 3 and 10 µg/kg follitropin delta, respectively, which indicated that the optimal hCG/FSH ratio and corresponding hCG efficacious dose was inversely related to the FSH dose. There was no difference between CG beta and CG alfa for the dose effect on the number of ovulated oocytes or ovarian weight. Histology data indicated many cystic follicles following high CG beta exposure which may represent atretic follicles prior to triggering follicular maturation and ovulation. Limitations, reasons for caution This is the first study demonstrating that the FSH dose in combination with the hCG dose determines the effect on multiple follicle growth, ovulation, and atresia. These observations need to be confirmed in clinical research, as doses and ratios applied in the rat cannot be extrapolated to the clinical setting. Wider implications of the findings A better understanding of the effect of different FSH to hCG ratios will help to improve current mixed protocols and design future recombinant combination products providing the optimal treatment outcome for each individual patient. Trial registration number not applicable

REVIEW ON THE IMPACT AND CONSEQUENCES OF THE OCCURRENCE OF MULTIPLE BIRTHS IN CATTLE AND GOATS

Background: The large animal species such as cattle, buffaloes and horses are monotocous with one or sometimes two newborns per birth whereas small farm animal species such as sheep, goats and pigs are usually polytocous animals are highly prolific and especially pigs often produce a dozen newborns at each farrowing. Cattle usually produce only one calf per gestation resulting from ovulation of a single follicle. The most common form of twinning in cattle occurs due to multiple ovulations which may produce dizygotic twins. The twin births in dairy cattle often negatively impacts the reproduction, production, health and reduces the productive lifespan of cows. Therefore, there is a great interest to know the multiple ovulations and multiple births to reduce the twinning rate in dairy cattle herds. Objective: This review updates the status of multiple births and its impact and consequences on production of dairy cattle and goats. Materials and Methods: The related literatures on the multiple births in cattle and goats have been reviewed for which the search was carried out in Google Scholar, PubMed, CrossRef, Banglajol and also the online daily newspapers. Results: Although multiple births with up to quadruplets have been reported from different countries, the prevalence of twin births are commonly reported in dairy cattle. The prevalence of twinning rates are varied widely in different breeds like twin calving in Holstein Friesian cattle is 3 to 5%, 5.6% Spanish dairy herd and 3.9% in Iranian Holsteins, whereas triplet and quadruplet births represent 0.015% and 0.004% of the total births, respectively. Twin calving shorten gestation length, increased dystocia, stillbirths, decrease birth weight, perinatal calf mortality, retained placenta, decrease milk production, increases the occurrence of metabolic diseases, reduced conception rate, increased calving interval, shorten the productive lifespan of the dam and increases overall culling rate. Two strategies- the transfer of a single embryo produced in vitro and follicular drainage of co-dominant follicles at AI have been suggested to prevent twin pregnancies. Conclusion: Multiple births in dairy cattle is not desirable due to negative effects on both cows that calve twins and calves born as twins that result in economic losses in dairy herds. Regardless of the direct effect of multiple births on health and fertility, reducing the occurrence of multiple ovulations to decrease the risk of twin births is desirable to mitigate the negative consequences of twinning in dairy cattle. The estimated losses due to twinning range between US$ 59 to 161 per twin pregnancy and attempting manual embryo reduction decreased the economic losses of a twin pregnancy by US $ 23 to 45. Bangladesh scientists discovered a new technique to produce twin calves but the future research on this aspect need to consider the negative effects of twin births in cattle.

In vivo embryo production in bovine donors with low and high antral follicle counts superovulated with low and high FSH doses

This study evaluated the embryo yield in Bos indicus donors with low and high antral follicle counts (AFCs) subjected to a multiple ovulation and embryo transfer (MOET) program using low and high FSH doses for superovulation. Donors (n = 16) underwent a presynchronization E2/P4-based protocol 30 days (D-30) before starting the MOET program. After AFC evaluation (D-26), donors with low (n = 8; ≤ 15 follicles; mean = 10.00 ± 0.91 follicles) and high AFCs (n = 8; ≥ 25 follicles; mean = 36.13 ± 6.05 follicles) underwent a first program involving a dose of 150 IU of FSH (low-dose). Then, 45 days later, all donors underwent a second program involving a dose of 300 IU of FSH (high-dose). MOET was performed using a conventional timed superstimulation protocol with decreasing FSH applications at 12 h intervals, and uterine flushing was performed 7 days after ovulation induction. Data were analyzed by two models employing ANOVA and Tukey's test in a procedure for an adjusted mixed effect model (P ≤ 0.05). The first model contemplated a split-plot scheme and second model considered the treatment effect. An effect of AFC was observed only for the number of corpora lutea (CLs), which was higher (P = 0.01) in donors with high AFCs than in those with low AFCs. For all other variables monitored, donors with low AFCs showed similar reproductive performance to high-AFC donors (P > 0.1). In general, the 300 IU of FSH dose resulted in significantly greater (P < 0.01) numbers of CL, total structures, and viable and freezable embryos than the 150 IU dose. There was no interaction of AFC*FSH (P > 0.05). However, a significant treatment effect was observed, which showed that donors with a high AFC treated with a high FSH dose presented the greatest mean numbers of CL (P = 0.002), total structures (P = 0.002), viable embryos (P = 0.04) and freezable embryos (P = 0.004). However, donors with a low AFC treated with 300 IU of FSH exhibited similar embryo yield to that of the high-AFC group treated with 300 IU of FSH (P > 0.1). In conclusion, the embryo yield was not influenced by the AFC category but was influenced by the FSH dose. Furthermore, the significant treatment effect revealed that high-AFC donors superovulated with the highest FSH dose presented the best performance in terms of embryo yield.

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.

Embryo biotechnologies in sheep: Achievements and new improvements.

To date, large-scale use of multiple ovulation and embryo transfer (MOET) programmes in ovine species is limited due to unpredictable results and high costs of hormonal stimulation and treatment. Therefore, even if considered reliable, they are not fully applicable in large-scale systems. More recently, the new prospects offered by in vitro embryo production (IVEP) through collection of oocytes post-mortem or by repeated ovum pick-up from live females suggested an alternative to MOET programmes and may be more extensively used, moving from the exclusive research in the laboratory to field application. The possibility to perform oocytes recovery from juvenile lambs to obtain embryos (JIVET) offers the great advantage to significantly reduce the generation interval, speeding the rate of genetic improvement. Although in the past decades several studies implemented novel protocols to enhance embryo production in sheep, the conditions of every single stage of IVEP can significantly affect embryo yield and successful transfer into the recipients. Moreover, the recent progresses on embryo production and freezing technologies might allow wider propagation of valuable genes in small ruminants populations and may be used for constitution of flocks without risks of disease. In addition, they can give a substantial contribution in preserving endangered breeds. The new era of gene editing might offer innovative perspectives in sheep breeding, but the application of such novel techniques implies involvement of specialized operators and is limited by relatively high costs for embryo manipulation and molecular biology analysis.

Breeding schemes with optimum-contribution selection or truncation selection for beef cattle destined for use on dairy females

We tested the hypothesis that the size of a beef cattle population destined for use on dairy females is smaller under optimum-contribution selection (OCS) than under truncation selection (TRS) at the same genetic gain (ΔG) and the same rate of inbreeding (ΔF). We used stochastic simulation to estimate true ΔG realized at a 0.005 ΔF in breeding schemes with OCS or TRS. The schemes for the beef cattle population also differed in the number of purebred offspring per dam and the total number of purebred offspring per generation. Dams of the next generation were exclusively selected among the one-year-old heifers. All dams were donors for embryo transfer and produced a maximum of 5 or 10 offspring. The total number of purebred offspring per generation was: 400, 800, 1,600 or 4,000 calves, and it was used as a measure of population size. Rate of inbreeding was predicted and controlled using pedigree relationships. Each OCS (TRS) scheme was simulated for 10 discrete generations and replicated 100 (200) times. The OCS scheme and the TRS scheme with a maximum of 10 offspring per dam required approximately 783 and 1,257 purebred offspring per generation to realize a true ΔG of €14 and a ΔF of 0.005 per generation. Schemes with a maximum of 5 offspring per dam required more purebred offspring per generation to realize a similar true ΔG and a similar ΔF. Our results show that OCS and multiple ovulation and embryo transfer act on selection intensity through different mechanisms to achieve fewer selection candidates and fewer selected sires and dams than under TRS at the same ΔG and a fixed ΔF. Therefore, we advocate the use of a breeding scheme with OCS and multiple ovulation and embryo transfer for beef cattle destined for use on dairy females because it is favorable both from an economic perspective and a carbon footprint perspective.

Ovulatory response to GnRH agonist during early and late fall in mares

This study aimed to assess the ovulatory response of deslorelin acetate during the fall and the response to PGF2α 8 d post-ovulation. One hundred estrous cycles from 22 mares kept in 40° latitude were evaluated. Mares were checked by transrectal ultrasonography until a preovulatory follicle was detected and ovulation induced with deslorelin acetate. Ovulation was confirmed by ultrasonography performed at 24, 36 h post-induction and then repeated at 2-h intervals post-induction. Serum progesterone concentrations and luteal tissue area were determined daily to assess CL function. A dose of PGF2α was administered 8 d post-ovulation and interval to the subsequent ovulation was observed; each mare completed up to five cycles. The effects of local climate on endpoints were analyzed. Cycles were grouped as early (Sept 13, 2020–Oct 31, 2020; n = 55; 22 mares) and late fall (Nov 1, 2020–Dec 31, 2020; n = 45; 20 mares) based on the date of induction. The overall number of cycles with ovulations between 24 and 48 h was 90%. The number of multiple ovulations were similar between early (n = 5) and late (n = 4) fall (P = 0.87). There were no differences in deemed spontaneous ovulations occurring before 24 h between early (n = 6) and late (n = 2) fall (P = 0.29). Two failures to respond to deslorelin by 48 h were recorded in early fall and none in the late fall. The interval from induction to ovulation was similar in early (40.6 ± 0.4 h) and late (41.2 ± 0.5 h) fall (P = 0.55). The percentage of mares ovulating between 36 and 48 h post-deslorelin did not vary between early and late fall (91 vs. 95%, P = 0.21), as did not for ovulation occurring between 38 h and 44 h (62 vs. 60%, P = 0.69). Edema scores varied with time relative to ovulation (P < 0.001) and were lower in late fall (P = 0.01). Progesterone concentrations varied with time (P < 0.001) but did not differ between early and late fall (P = 0.73) and correlated weakly with the luteal area (r = 0.13; P = 0.031). Follicles <35 mm at the PGF2α had a shorter interval to the next ovulation than follicles ≥ 35 mm (9.2 ± 0.5 d vs. 10.6 ± 1.2 d) (P = 0.03). Lower temperature was associated with a smaller follicle size at induction (P = 0.0021) and ovulation (P = 0.009) and lower relative humidity was associated with a larger follicle size at ovulation (P = 0.032). In conclusion, cycling mares displayed a highly efficacious response to deslorelin acetate and apparently normal luteal function during the fall, despite lower edema scores in late fall.

Effect of FSH Stimulation of Ovaries on in vitro Maturation of Sahiwal Oocytes Collected by Ovum Pick-up (OPU) Method

Background: For conservation of breeds and faster multiplication of superior germplasm in a short period, ovum pick-up- In vitro embryo production (OPU-IVEP) in combination with embryo transfer (ET) can be a viable alternative to the multiple ovulation embryo transfer (MOET). The aim of the present study was to evaluate the effect of FSH stimulation on follicular population, oocyte recovery rate and in vitro maturation of oocytes collected by ovum pick-up in Sahiwal cows. Methods: Sixteen Sahiwal cows aged 3-6 years were randomly divided into two groups. Animals in group 1 (Non-stimulated, n=8) were subjected to ovum pick-up (OPU) twice at 96h interval at random stage of estrous cycle. Animals in group 2 (FSH stimulated, n=8) were subjected to FSH prestimulation (Follitropin-V, 200 mg i/m in 3 tapering doses 100, 60, 40 mg) prior to OPU 1 and with a duration of 96 hrs interval OPU 2 performed. Result: There was significant difference (p less than 0.05) observed between FSH stimulated and non-stimulated group in mean number of follicles available for aspiration (15.31±1.56 and 6.88±0.55, respectively), mean number of oocytes recovered (4.94±0.70 and 3.25±0.40, respectively), cumulus cell expansion rate (92.95 and 83.7% respectively) and 1st polar body extrusion rate (74.64 and 67.44%, respectively). In conclusion, 200 mg of FSH stimulation with decreasing dose prior to OPU increased the follicular population and increased more number of medium and large follicles available for aspiration. FSH pre-treatment also improved the mean number of oocyte recovery and maturation rate compared to non-stimulated group.