The contribution of efficient production of monozygotic twins to beef cattle breeding

In vitro developmental competence of bovine demi-embryos generated by blastomere separation and blastocyst bisection

The efficiency of bovine in vitro embryo production can be significantly improved by splitting embryos at different stages. However, the blastocyst quality of in vitro-produced demi-embryos remains unexplored. The objective of this research was to compare embryo developmental rates and quality of bovine demi-embryos produced by two different strategies: (a) embryo bisection (BSEC) and (b) 2-cell blastomere separation (BSEP). To determine demi-embryos quality, we evaluated total blastocyst cell number and proportion of SOX2+ cells. Additionally, the expression of SOX2, NANOG, OCT4, CDX2, IFNT, BAX and BCL genes and let-7a and miRNA-30c Micro RNAs was analysed. BSEP resulted in improved blastocyst development, higher ICM cells and a significantly higher expression of IFNΤ than demi-embryos produced by BSEC. Let-7a, which is associated with low pregnancy establishment was detected in BSEC, while miRNA-30c expression was observed in all treatments. In conclusion, BSEP of 2-cell embryos is more efficient to improve in vitro bovine embryo development and to produce good quality demi-embryos based on ICM cell number and the expression pattern of the genes explored compared to BSEC.

Development and growth of bovine calves demi-embryos

The aim of this study was to investigate the growth and development of animals produced from demi-embryos and compare them with whole embryos from fetus to adult life. To achieve this, calves produced from fresh demi-embryos and whole embryos were individually transferred and monitored from 60 days of pregnancy until slaughter at 550 days. Ultrasound scans were conducted on fetuses at 60 and 90 days to evaluate the biparietal, abdominal, umbilical cord, orbital, and aorta diameters. Subsequently, morphological traits of newborn calves were measured at 0, 7, and 21 days (N = 18). Live weight was recorded at birth, weaning, and every 30 days thereafter until slaughter at 550 days. The growth curve of each group was modeled using logistic regression, and the factors of the respective functions were compared. As early as 60 days of pregnancy, ultrasound evaluations revealed no morphometric differences between fetuses produced from demi-embryos and those from whole embryos. This lack of differentiation persisted in the morphometric evaluations of newborns up to 21 days of age, as well as in live weight and the growth curve from birth to slaughter. Moreover, there were no significant differences between the groups in terms of rib eye area and fat thickness evolution. Consequently, individuals from demi-embryos exhibited no discernible disparities to those whole embryos in growth and development from 60 days of gestation, through birth, and into adulthood.

Negative photoperiod induces an increase in the number of ovulations in dairy cattle

This study sought to examine the impact of negative photoperiod on the incidence of multiple ovulations and pregnancies in dairy cattle. The study population consisted of 5,373 pregnant cows in their third or greater lactation that experienced their first post-partum pregnancy after spontaneous estrus. The positive photoperiod (increasing day-length) extends from December 22 to June 21, whereas the negative photoperiod (decreasing day-length) extends from June 22 to December 21. The odds ratios (ORs) for multiple ovulations and pregnancies in cows that became pregnant during the negative photoperiod and the remaining cows that became pregnant during the positive photoperiod were 1.4 and 1.3 (P < 0.0001), respectively. The ORs for cows that became pregnant ≥ 90 days in milk and the remaining cows that became pregnant < 90 days in milk were 4.3 and 4.1 (P < 0.0001), respectively. No significant differences were detected in the monthly rates of multiple ovulations or pregnancies during positive and negative photoperiods. Thus, the present study demonstrates that the ovarian function in cows is related to changes in day-length, with decreasing day-length being associated with greater multiple ovulation and pregnancy rates. The present study also shows that positive and negative photoperiods exhibit different trends. The results of this study are consistent with a growing body of work demonstrating the effects of photoperiod patterns on the reproductive physiology of cows, with clear implications for twin pregnancy prevention.

Update on Mesenchymal Stem Cells: A Crucial Player in Cancer Immunotherapy

The idea of cancer immunotherapy has spread, and it has made tremendous progress with the advancement of new technology. Immunotherapy, which serves to assist the natural defenses of the body in eradicating cancerous cells, is a remarkable achievement that has revolutionized both cancer research and cancer treatments. Currently, the use of stem cells in immunotherapy is widespread and shares a special characteristic, including cancer cell migration, bioactive component release, and immunosuppressive activity. In the context of cancer, mesenchymal stem cells (MSCs) are rapidly being identified as vital stromal regulators of tumor progression. MSCs therapy has been implicated in treating a wide range of diseases, including bone damage, autoimmune diseases, and particularly hematopoietic abnormalities, providing stem cell-based therapy with an extra dimension. Moreover, the implication of MSCs does not have ethical concerns, and the complications known in pluripotent and totipotent stem cells are less common in MSCs. MSCs have a lot of distinctive characteristics that, when coupled, make them excellent for cellular-based immunotherapy and as vehicles for gene and drug delivery in a variety of inflammations and malignancies. MSCs can migrate to the inflammatory site and exert immunomodulatory responses via cell-to-cell contacts with lymphocytes by generating soluble substances. In the current review, we discuss the most recent research on the immunological characteristics of MSCs, their use as immunomodulatory carriers, techniques for approving MSCs to adjust their immunological contour, and their usages as vehicles for delivering therapeutic as well as drugs and genes engineered to destroy tumor cells.

Cloning in action: can embryo splitting, induced pluripotency and somatic cell nuclear transfer contribute to endangered species conservation?

The term 'cloning' refers to the production of genetically identical individuals but has meant different things throughout the history of science: a natural means of reproduction in bacteria, a routine procedure in horticulture, and an ever-evolving gamut of molecular technologies in vertebrates. Mammalian cloning can be achieved through embryo splitting, somatic cell nuclear transfer, and most recently, by the use of induced pluripotent stem cells. Several emerging biotechnologies also facilitate the propagation of genomes from one generation to the next whilst bypassing the conventional reproductive processes. In this review, we examine the state of the art of available cloning technologies and their progress in species other than humans and rodent models, in order to provide a critical overview of their readiness and relevance for application in endangered animal conservation.

Lab partners: oocytes, embryos and company. A personal view on aspects of oocyte maturation and the development of monozygotic twins

The present review addresses the oocyte and the preimplantation embryo, and is intended to highlight the underlying principle of the "nature versus/and nurture" question. Given the diversity in mammalian oocyte maturation, this review will not be comprehensive but instead will focus on the porcine oocyte. Historically, oogenesis was seen as the development of a passive cell nursed and determined by its somatic compartment. Currently, the advanced analysis of the cross-talk between the maternal environment and the oocyte shows a more balanced relationship: Granulosa cells nurse the oocyte, whereas the latter secretes diffusible factors that regulate proliferation and differentiation of the granulosa cells. Signal molecules of the granulosa cells either prevent the precocious initiation of meiotic maturation or enable oocyte maturation following hormonal stimulation. A similar question emerges in research on monozygotic twins or multiples: In Greek and medieval times, twins were not seen as the result of the common course of nature but were classified as faults. This seems still valid today for the rare and until now mainly unknown genesis of facultative monozygotic twins in mammals. Monozygotic twins are unique subjects for studies of the conceptus-maternal dialogue, the intra-pair similarity and dissimilarity, and the elucidation of the interplay between nature and nurture. In the course of in vivo collections of preimplantation sheep embryos and experiments on embryo splitting and other microsurgical interventions we recorded observations on double blastocysts within a single zona pellucida, double inner cell masses in zona-enclosed blastocysts and double germinal discs in elongating embryos. On the basis of these observations we add some pieces to the puzzle of the post-zygotic genesis of monozygotic twins and on maternal influences on the developing conceptus.

In vitro embryo production from ewes at different physiological stages

BACKGROUND

The collection of ovaries from slaughterhouses is an important source of oocytes for in vitro embryo production. On the other hand, the physiological stage of slaughtered females varies and influences embryo production.

OBJECTIVES

The study examined the in vitro efficiency of embryos and demi-embryos from young, non-pregnant adult, and pregnant adult ewes from a local slaughterhouse.

METHODS

One thousand three hundred ovaries were collected from August to October 2020. The recovered oocytes were matured, fertilized, and cultured at 5% CO₂, 38.5°C, and 100% humidity. Embryo bisection was performed in 96 blastocysts (n = 32 per treatment). The demi-embryo pairs were incubated for their reconstitution for 12 h. SAS was used for data analysis.

RESULTS

The number of oocytes collected from the experimental group of non-pregnant adult ewes was higher (p ≤ 0.007) than those collected from the group of pregnant adult ewes (2.67 ± 0.19 vs. 2.18 ± 0.15 oocytes/group, respectively). The blastocyst rate was higher (p ≤ 0.0001) in the non-pregnant adult group (36.39%) than in the young (17.96%). The ratio of demi-embryos that recovered the blastocoelic cavity was higher (p < 0.05) in the young group (81.25%) than in the pregnant adult group (59.38%). The diameter of the demi-embryos was higher (p < 0.05) in the non-pregnant adult group (186.54 ± 8.70 μm) than those in the young and pregnant adult groups.

CONCLUSIONS

In conclusion, the in vitro embryo production efficiency was highest when using oocytes from non-pregnant adult ewes under the conditions of this study.

Potential of preimplantation genomic selection using the blastomere separation technique in bovine in vitro fertilized embryos

Preimplantation genomic selection combined with an in vitro embryo production system is expected as a means of accelerating genetic improvement in cattle. While micromanipulation-based biopsy approaches are often used to collect embryonic cells for genetic testing, they require expensive equipment and sophisticated skills, hindering the adoption of this system. In the present study, to develop a simple method for preimplantation genomic selection using the blastomere separation (BS) technique in bovine in vitro fertilized embryos, we examined the accuracy of single nucleotide polymorphism (SNP) genotyping and optimal cryopreservation method in demi-blastocysts produced by the BS technique. We demonstrated reliable SNP genotyping using DNA derived from demi-blastocysts. We indicated a suitable equilibrium time in vitrification solution for demi-blastocysts and succeeded obtaining pregnancies by the transfer of vitrified demi-blastocysts. In conclusion, our findings suggest that the BS technique provides a simple method for preimplantation genomic selection in bovine in vitro fertilized embryos.

The mystery of monozygotic twinning II: What can monozygotic twinning tell us about Amyoplasia from a review of the various mechanisms and types of monozygotic twinning?

Monozygotic (MZ) twins ("identical twins") are essentially unique to human beings. Why and how they arise is not known. This article reviews the possible different types of MZ twinning recognized in the previous article on twins and arthrogryposis. There appear to be at least three subgroups of MZ twinning: spontaneous, familial, and those related to artificial reproductive technologies. Each is likely to have different etiologies and different secondary findings. Spontaneous MZ twinning may relate to "overripe ova." Amyoplasia, a specific nongenetic form of arthrogryposis, appears to occur in spontaneous MZ twinning and may be related to twin-twin transfusion.

Twins in Dairy Herds. Is It Better to Maintain or Reduce a Pregnancy?

Simple Summary

In dairy herds, twin or other multiple pregnancies are not desirable as they compromise the health and productive lifespan of the cows. The mean productive lifespan of primiparous and secundiparous dairy cows delivering twins is about 300 and 200 days shorter, respectively, than that of cows delivering singletons. In addition, the long-term negative effects of twinning are not limited to the early lactation but continue for a period of up to 800 days after calving. Herd management options after diagnosing a twin pregnancy are discussed from an animal health and economic perspective.

Abstract

Multiple ovulations and so multiple pregnancies have increased recently in dairy cattle. The incidence of the double ovulation impact in high producers at insemination may be over 20%. Twin pregnancies are undesirable as they seriously compromise the welfare and productive lifespan of the cow and herd economy. Clinical problems extend from the time of pregnancy diagnosis to pregnancy loss, abortion or parturition. Early pregnancy loss or abortion of multiple pregnancies lead in most cases to culling. In cows reaching their term, mean productive lifespan is up to about 300 days shorter for cows delivering twins than for cows delivering singletons. While there is an urgent need to address multiple pregnancy prevention procedures in the foreseeable future, the incidence of twin pregnancies continues to rise in parallel with increased milk production. Herein, we review two contrasting measures proposed for the time of twin pregnancy diagnosis: (1) gonadotropin-releasing hormone treatment for pregnancy maintenance, or (2) embryo reduction. These options are discussed in terms of their implications for individual animal health and herd economy. Our main conclusions find that manual twin reduction has proven to be the best management option, whereas the use of prostaglandin F_2α for inducing abortion may be a better option than doing nothing.

Naturally monozygotic quadruplets in a Braford cow confirmed by DNA analysis: A case report

Cattle are a monotocous species, despite naturally conceived multiple births are sometimes observed. Although the number of twins has consistently increased, triplet and quadruplet pregnancies represent 0.015% and 0.004% of the total births, respectively. Multiple births are the result of multiple ovulation and/or the spontaneous cleavage of one fertilized oocyte, which is known as monozygotic (MZ) twinning. In cattle, approximately 5% to 14% of all twin births are MZ, and births with more than two MZ calves are extremely rare. Monozygotic animals are genetically identical, and those derived from two or more zygotes are genetically different. Furthermore, the presence of placental vascular anastomosis can result in foetal chimerism. Notwithstanding, animals born as single calves can be chimeras when one of the foetal twins dies undetected in utero. Here, we used DNA testing to study the zygotic condition of an unusual female quadruplet born from a Braford cow bred in a multi-sire natural mating system without hormone stimulation. Two tissues with different embryological origin were sampled to test zygosity and possible chimerism. The results showed an identical genotype, confirming they all originated in an MZ pregnancy and suggesting the lack of chimerism in all animals. The use of MZ twins in breeding and selection systems provides an alternative to the conventional progeny testing. Some works have suggested a genetic background of MZ twins in humans. This female and her daughters could be the founders of a lineage to study the possible inheritance of MZ multiple births in cattle.

To What Extent Does Photoperiod Affect Cattle Reproduction? Clinical Perspectives of Melatonin Administration – A Review

The seasonality of reproduction in most mammals is dictated by photoperiod, temperature and nutrition. Melatonin, mainly synthesized in the pineal gland, is generally accepted as the active mediator of photoperiod responses including reproduction. While non-pregnant heifers and cows show continuous sexual activity and are therefore not seasonal breeders, it has been suggested that photo-periodicity may influence the appearance of puberty in heifers and the onset of parturition. Further, the light/dark ratio may influence endocrine patterns of gestation and a shorter light period correlates with the incidence of twin pregnancies. This review considers specific aspects of the effects of photoperiod and melatonin on reproduction in dairy cattle and discusses the clinical applications of melatonin.

Managing embryonic and calves losses after twin pregnancies induced by transfer of in vitro-produced Nellore embryos

Two farms applying reproductive technology for the Nellore beef cattle were selected. Both farms had the same technology programme of oestrous synchronization and embryo transfer, but management was different, especially regarding twins pregnancies. In the present study, we followed the farms from the moment of oestrous synchronization, embryo transfer (two per cow), until delivery and first care of the calves. In farm A, cows presenting twin pregnancies (5 from 13) were submitted to delivery induction, as well as calves and cows were monitored after birth. In farm B, such management was not followed with the twin pregnant cows (31 from 49). In both farms, freemartinism was detected, but this was not a problem as none of the animals would be selected for breeding. No dystocia was observed in farm A, while 48% of the twin pregnancies in farm B ended up in dystocia. Furthermore, the mortality rate of new-born calves in farm A was 10%, while in farm B it reached 32%. Although twin pregnancies remain a concern, we showed here that proper management during and after delivery minimizes animal and economic losses.

Improved embryo survival following follicular drainage of subordinate follicles for twin pregnancy prevention in bi-ovular dairy cows

To prevent twin pregnancies in cattle, a simple transvaginal device can be used for follicular drainage. This study examines embryo survival following follicular drainage of the smaller pre-ovulatory follicle at timed artificial insemination (AI) in cows with a pre-ovulatory follicle in each ovary. The study groups established were a control group of 289 monovular cows, a non-drainage group of 114 bi-ovular cows and a follicular drainage group of 113 bi-ovular cows. All cows undergoing drainage developed a corpus luteum (CL) in the drained ovary. Pregnancy loss was recorded 56 days post-AI in 19.5% of the 149 cows that became pregnant. Pregnancy loss in the drainage group cows not suffering heat stress (3.8%) was significantly lower (P < 0.05) than in control non-heat stressed cows (20.9%) and heat-stressed non-drainage group cows (25%). Results indicate that CL induction by follicular drainage for twin pregnancy prevention may reduce the incidence of pregnancy loss.

Luteal activity following follicular drainage of subordinate follicles for twin pregnancy prevention in bi-ovular dairy cows

Twin pregnancy is undesirable in dairy cattle. This study examines luteal activity following ultrasound-guided puncture and drainage of the smaller pre-ovulatory follicle at timed AI in cows with a pre-ovulatory follicle in each ovary. Luteal activity was determined through Doppler ultrasonography and plasma progesterone (P4) concentrations. The effects of GnRH treatment on Day 7 post-AI on subsequent luteal activity were also assessed. Two study groups were established: a control group of 29 cows and a follicular drainage (FD) group of 28 cows. After drainage, all cows developed a corpus luteum (CL) in the drained ovary. On Day 21 post-AI, drainage-induced CL and fellow CL were similar in terms of size and vascularization. According to a GLM repeated measures analysis of variance (P < 0.001), non-treated drained cows had lower P4 concentrations on Day 21 post-AI than non-treated non-drained cows, whereas GnRH treated cows, both drained and non-drained, showed the highest P4 concentrations at this time point. Twin pregnancy was recorded in 3 of the 8 pregnant control cows, whereas no twins were observed in the FD group. Our results indicate that luteal structures following follicular drainage were functional. As for the presence of an additional CL, this could suggest a reduced risk of pregnancy loss. In addition, luteal activity was significantly increased following GnRH treatment on Day 7 post-AI in drained cows.