Preliminary trials of a specific gravity technique in the determination of early embryo growth potential†

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Published on: July 26, 2019

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S.D. Prien,1,2,* C.E. Wessels,2 and L.L. Penrose1

. 2015 Sep; 30(9): 2076–2083.
Published online 2015 Jul 22. doi: 10.1093/humrep/dev178
PMCID: PMC4542720
PMID: 26202920

Abstract

STUDY QUESTION

Can a modified specific gravity technique be used to distinguish viable from nonviable embryos?

SUMMARY ANSWER

Preliminary data suggests a modified specific gravity technique can be used to determine embryo viability and potential for future development.

WHAT IS KNOWN ALREADY

Single embryo transfer (SET) is fast becoming the standard of practice. However, there is currently no reliable method to ensure development of the embryo transferred.

STUDY DESIGN, SIZE, DURATION

A preliminary, animal-based in vitro study of specific gravity as a predictor of embryo development using a mouse model.

PARTICIPANTS/MATERIALS, SETTING, METHODS

After a brief study to demonstrate embryo recovery, experiments were conducted to assess the ability of the specific gravity system (SGS) to distinguish between viable and nonviable embryos. In the first study, 1-cell mouse embryos were exposed to the SGS with or without previous exposure to an extreme heat source (60°C); measurements were repeated daily for 5 days. In the second experiment, larger pools of 1-cell embryos were either placed directly in culture or passed through the SGS and then placed in culture and monitored for 4 days.

MAIN RESULTS AND THE ROLE OF CHANCE

In the first experiment, viable embryos demonstrated a predictable pattern of descent time over the first 48 h of development (similar to previous experience with the SGS), while embryos that were heat killed demonstrated significantly altered drop patterns (P < 0.001); first descending faster. In the second experiment, average descent times were different for embryos that stalled early versus those that developed to blastocyst (P < 0.001). Interestingly, more embryos dropped through the SGS developed to blastocyst than the culture control (P < 0.01).

LIMITATIONS, REASONS FOR CAUTION

As this is a preliminary report of the SGS technology determining viability, a larger embryo population will be needed. Further, the current in vitro study will need to be followed by fecundity studies prior to application to a human population.

WIDER IMPLICATIONS OF THE FINDINGS

If proven, the SGS would provide a noninvasive means of assessing embryos prior to transfer after assisted reproductive technologies procedures, thereby improving fecundity and allowing more reliable SET.

STUDY FUNDING/COMPETING INTEREST(S)

The authors gratefully acknowledge the funding support of the U.S. Jersey Association, the Laura W. Bush Institute for Women’s Health and a Howard Hughes Medical Institute grant through the Undergraduate Science Education Program to Texas Tech University. None of the authors have any conflict of interest regarding this work.

TRIAL REGISTRATION NUMBER

none.

Keywords: embryo development, embryo selection, embryo viability, specific gravity, buoyance, noninvasive, zygote, blastocyst

In vitro culture systems: how far are we from optimal conditions?

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Published on: July 25, 2019

C. Wrenzycki

http://dx.doi.org/10.21451/1984-3143-AR869

Anim Reprod, vol.13, n3, p.279-282, 2016

Abstract

Over the past decades in vitro production (IVP) of bovine embryos has been significantly improved. Nevertheless, embryos generated in vitro still differ from their in vivo produced counterparts. Embryos must adjust to multiple microenvironments at preimplantation stages. Consequently, maintaining or mimicking the in vivo situation in vitro will aid to improve the quality and developmental competence of the resulting embryo.

cattle, embryo, in vitro production

Articles of Interest

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Published on: April 17, 2019

Significant heparin effect on bovine embryo development during sexed in vitro fertilization

Consequences of bovine oocyte maturation, fertilization or early embryo development in vitro versus in vivo: Implications for blastocyst yield and blastocyst quality

Sex control by Zfy siRNA in the dairy cattle

Daily administration of a GnRH analogue enhances sperm quality in bucks during the non-breeding season

Maternal age influences the number of primordial follicles in the ovaries of yearling Angus heifers

Role of cAMP modulator supplementations during oocyte in vitro maturation in domestic animals

Factors in cattle affecting embryo transfer pregnancies in recipient animals

Comparison of luteolysis and timed artificial insemination pregnancy rates after administration of PGF2α in the muscle or the ischiorectal fossa in cattle

Large-scale transcriptional analysis of bovine embryo biopsies in relation to pregnancy success after transfer to recipients

Effects of supplementation of medium with different antioxidants during in vitro maturation of bovine oocytes on subsequent embryo production

Influence of bovine serum albumin and fetal bovine serum supplementation during in vitro maturation on lipid and mitochondrial behaviour in oocytes and lipid accumulation in bovine embryos

50 Survival of sexed ivf-derived bovine embryos frozen at different preimplementation stages of development

141 Bovine embryo development rats are affected when oocytes are matured in different vials containing hepes/bicarbonate buffered medium

The ischiorectal fossa: an alternative route for the administration of prostaglandin in cattle

Effects of nutrition and genetics on fertility in dairy cows

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Published on: April 17, 2019

https://www.publish.csiro.au/RD/RD18364

Reproduction, Fertility and Development 31(1) 40-54 https://doi.org/10.1071/RD18364
Published online: 3 December 2018

Alex Bach

Institucio´Catalana de Recerca i Estudis Avanc¸ats (Barcelona 08007, Spain) and Department of Ruminant Production, Institut de Recerca i Tecnologies Agroalimenta`ries (Caldes de Montbui, 08140 Spain). Email: alex.bach@icrea.cat

Optimal reproductive function in dairy cattle is mandatory to maximise profits. Dairy production has progressively improved milk yields, but, until recently, the trend in reproductive performance has been the opposite. Nutrition, genetics, and epigenetics are important aspects affecting the reproductive performance of dairy cows. In terms of nutrition, the field has commonly fed high-energy diets to dairy cows during the 3 weeks before calving in an attempt to minimise postpartum metabolic upsets. However, in the recent years it has become clear that feeding high-energy diets during the dry period, especially as calving approaches, may be detrimental to cow health, or at least unnecessary because cows, at that time, have low energy requirements and sufficient intake capacity. After calving, dairy cows commonly experience a period of negative energy balance (NEB) characterised by low blood glucose and high non-esterified fatty acid (NEFA) concentrations. This has both direct and indirect effects on oocyte quality and survival. When oocytes are forced to depend highly on the use of energy resources derived from body reserves, mainly NEFA, their development is compromised due to a modification in mitochondrial b-oxidation. Furthermore, the indirect effect of NEB on reproduction is mediated by a hormonal (both metabolic and reproductive) environment. Some authors have attempted to overcome the NEB by providing the oocyte with external sources of energy via dietary fat. Conversely, fertility is affected by a large number of genes, each with small individual effects, and thus it is unlikely that the decline in reproductive function has been directly caused by genetic selection for milk yield per se. It is more likely that the decline is the consequence of a combination of homeorhetic mechanisms (giving priority to milk over other functions) and increased metabolic pressure (due to a shortage of nutrients) with increasing milk yields. Nevertheless, genetics is an important component of reproductive efficiency, and the incorporation of genomic information is allowing the detection of genetic defects, degree of inbreeding and specific single nucleotide polymorphisms directly associated with reproduction, providing pivotal information for genetic selection programs. Furthermore, focusing on improving bull fertility in gene selection programs may represent an interesting opportunity. Conversely, the reproductive function of a given cow depends on the interaction between her genetic background and her environment, which ultimately modulates gene expression. Among the mechanisms modulating gene expression, microRNAs (miRNAs) and epigenetics seem to be most relevant. Several miRNAs have been described to play active roles in both ovarian and testicular function, and epigenetic effects have been described as a consequence of the nutrient supply and hormonal signals to which the offspring was exposed at specific stages during development. For example, there are differences in the epigenome of cows born to heifers and those born to cows, and this epigenome seems to be sensitive to the availability of methyl donor compounds of the dam. Lastly, recent studies in other species have shown the relevance of paternal epigenetic marks, but this aspect has been, until now, largely overlooked in dairy cattle.

Additional keywords: Amino acids, Epigenetics, Fat, Glucose, Minerals, Reproduction, Vitamins

Antral follicle population in prepubertal and pubertal heifers

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Published on: April 17, 2019

https://www.publish.csiro.au/RD/RD18344

Reproduction, Fertility and Development 31(1) 10-16 https://doi.org/10.1071/RD18344
Published online: 3 December 2018

M. M. Seneda (A,D), F. Morotti (A), A. F. Zangirolamo (A,B), N. C. da Silva (A), K. Sanches (A), W. Blaschi (C), and T. R. R. Barreiros (C)

A Universidade Estadual de Londrina, Laborato´ rio de Reproduc¸a˜o Animal, Departamento de Clı´nicas Veterina´rias – Centro de Cieˆncias Agra´rias – Universidade Estadual de Londrina, Londrina, Parana, Brazil. B National Institute of Science and Technology for Dairy Production Chain (INCT–LEITE), Universidade Estadual de Londrina, Rodovia Celso Garcia Cid-Campus Universita´rio, PO Box 10011, Londrina, Parana 86057-970, Brazil. C Universidade Estadual do Norte do Parana´ , Laborato´ rio de Biotecnologia da Reproduc¸a˜o Animal, Departamento de Veterina´ria e Produc¸a˜o Animal, Rodovia BR – 369, Km 54, Vila Maria, Bandeirantes, Parana 86360-000, Brazil. D Corresponding author. Email: marcelo.seneda@uel.br

The antral follicle count (AFC) is an important tool in the selection of bovine females destined for biotechnology. However, little is known about AFC in prepubertal and pubertal heifers. Some challenges inherent to the physiology of young females must be considered to achieve efficient rates with different procedures, such as ovum pick-up and IVF. This paper covers some important topics about ovarian physiology related to the population of antral follicles and reproductive efficiency in young female cattle.

Additional keywords: Bos indicus, Bos taurus, calf, embryo production.

Cryopreservation and microfluidics: a focus on the oocyte

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Published on: April 17, 2019

https://www.publish.csiro.au/RD/RD18326

Reproduction, Fertility and Development 31(1) 93-104  https://doi.org/10.1071/RD18326
Published online: 3 December 2018

Gary D. Smith (A,C) and Shuichi Takayama (B)

A Departments of Obstetrics & Gynecology, Physiology, and Urology, Reproductive Sciences Program, University of Michigan, Ann Arbor, MI 48108, USA. B Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology & Emory University School of Medicine, Atlanta, GA 30332, USA. C Corresponding author. Email: smithgd@umich.edu

Cryopreservation of gametes and embryos has played a critical role in successful assisted reproductive technologies in rodents, domestic farm species, endangered species and humans. With improved success, and changing needs, the utility of gamete or embryo cryopreservation has escalated. In this review we address some of the foundational history of mammalian cryobiology, species-specific utilities, fundamental understandings of cryoprotectant agents and their use in slow-rate freezing and vitrification, and expand on the recent success and uses of oocyte vitrification and warming. In the area of female gamete cryopreservation, emphasis will be placed on not just cell survival, but also perceived and measured affects of cryopreservation on intracellular structures and functions that affect subsequent completion of meiosis with chromatin segregation fidelity, normal fertilisation and embryonic developmental competence. We compare and contrast data from cow, mouse and humans with a focus on using species-comparative developmental biology to guide future studies for improving methodologies for all species. The application of the relatively new technology microfluidics is discussed in relation to moving gradually (i.e. changing the solution over cells in an automated fashion) compared with the stepwise manual movement of cells through changing solution currently used. This use of microfluidics to change the way cells are exposed to cryoprotectant agents can provide new insights into the effects of osmotic stress and cellular strain rates previously unappreciated, precise methods of computational and biological data acquisition and appreciation of morphometric changes to cellular structure in response to different osmotic stresses and strain rates achieved with varying cryoprotectant exposures. Collectively, these devices and methodologies provide a means of achieving incremental improvement of oocyte and zygote cryopreservation with normalised and improved developmental competence. Finally, we look to the past and the future to acknowledge the accomplishment of leaders in the field of mammalian gamete and embryo cryobiology, their inspirational works, their tireless dissemination of information and the potential of new technologies in bioengineering to improve the efficiency and safety of gamete and embryo cryopreservation.

Additional keywords: embryos, gametes, vitrification.

Articles of Interest

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Published on: December 27, 2018

Consequences of bovine oocyte maturation, fertilization or early embryo development in vitro versus in vivo: Implications for blastocyst yield and blastocyst quality

Cryopreservation of preimplantation embryos of cattle, sheep, and goats

A simple medium enables bovine embryos to be held for seven days at 4°C

Aggressive attempted escape behavior during head-lock restraint reduced reproductive performances in Holstein heifers

Effects of feeding a source of omega-3 fatty acid during the early postpartum period on the endocannabinoid system in the bovine endometrium

Relationships between numbers of antral follicles and postpartum interval in Brahman females

Administration of an herbal powder based on traditional Chinese veterinary medicine enhanced the fertility of Holstein dairy cows affected with retained placenta

Influence of cycle stage, age and endometrial biopsy score on oxytocin receptor distribution and gene expression in the cervix and uterus of non-pregnant mares

Comparison of pregnancy in cattle when non-vitrified and vitrified in vitro-derived embryos are transferred into recipients

 

Use of FSH in two different regimens for ovarian superstimulation prior to ovum pick up and in vitro embryo production in Holstein cows

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Published on: July 6, 2018

Authors: Júlio César Barboza da Silva, Roberta Machado Ferreira, Milton Maturana Filho, Julianne de Rezende Naves, Thiago Santin, Guilherme Pugliesi, Ed Hoffmann Madureira

Publication: Theriogenology

Publisher: Elsevier

Date of Publication: 1 March, 2017

Link: https://www.ncbi.nlm.nih.gov/pubmed/28166990

Superstimulation prior to the ovum pick-up to improve in vitro embryo production in lactating and non-lactating Holstein cows

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Published on: July 6, 2018

Authors: L.M. Vieira, C.A. Rodrigues, A. Castro Netto, B.M. Guerreiro, C.R.A. Silveira, R.J.C. Moreira, M.F. Sá Filho, G.A. Bó, R.J. Mapletoft, P.S. Baruselli

Publication: Theriogenology

Publisher: Elsevier

Date of Publication: 15 July 2014

Link: https://www.ncbi.nlm.nih.gov/pubmed/24839924

Short communication: Follicle superstimulation before ovum pick-up for in vitro embryo production in Holstein cows

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Published on: July 6, 2018

Authors: Louise H. Oliveira, Carlos P. Sanches,Adriano S. Seddon, Marcio B. Veras, Flávio A. Lima, Pedro L.J. Monteiro, Milo C. Wiltbank, Roberto Sartori

Publication: Journal of Dairy Science

Publisher: Elsevier

Date of Publication: November 2016

Link: https://www.journalofdairyscience.org/article/S0022-0302(16)30571-9/pdf

Articles of Interest

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Published on: July 6, 2018

In vitro sperm quality and DNA integrity of SexedULTRA sex-sorted sperm compared to non-sorted bovine sperm

 

Angiocoupling between the dominant follicle and corpus luteum during waves 1 and 2 in Bos taurus heifers

 

Improved uterine immune mediators in Holstein cows supplemented with rumen-protected methionine and discovery of neutrophil extracellular traps (NET)

 

Hormonal strategy to reduce suckled beef cow handling for timed artificial insemination with sex-sorted semen

 

Differential release of cell-signaling metabolites by male and female bovine embryos cultured in vitro

 

Synchronization treatments previous to natural breeding anticipate and improve the pregnancy rate of postpartum primiparous beef cows

 

Heat-shock-induced cathepsin B activity during IVF and culture compromises the developmental competence of bovine embryos

 

Associations between dairy cow inter-service interval and probability of conception

 

μ-Calpain (CAPN1), calpastatin (CAST), and growth hormone receptor (GHR) genetic effects on Angus beef heifer performance traits and reproduction

 

Assessment of the temperature cut-off point by a commercial intravaginal device to predict parturition in Piedmontese beef cows

 

Variations in bovine embryo production between individual donors for OPU-IVF are closely related to glutathione concentrations in oocytes during in vitro maturation

 

Eventual re-vitrification or storage in liquid nitrogen vapor does not jeopardize the practical handling and transport of vitrified pig embryos

 

Cryopreservation and in vitro culture of white-tailed deer ovarian tissue

 

Preparation, characterization and application of long-acting FSH analogs for assisted reproduction

 

Aromatase inhibitors: A new approach for controlling ovarian function in cattle

 

Pursuit of a method for single administration of pFSH for superstimulation in cattle: What we have learned

 

Progesterone-releasing devices for cattle estrus induction and synchronization: Device optimization to anticipate shorter treatment durations and new device developments

 

Potential of connected devices to optimize cattle reproduction

 

Vaginal temperature measurement by a wireless sensor for predicting the onset of calving in Japanese Black cows

 

Effect of different chorionic gonadotropins on final growth of the dominant follicle in Bos indicus cows

 

Effect of different shipping temperatures (∼22 °C vs. ∼7 °C) and holding media on blastocyst development after overnight holding of immature equine cumulus-oocyte complexes

 

A recovery time after warming restores mitochondrial function and improves developmental competence of vitrified ovine oocytes

 

Additional small dose of prostaglandin F at timed artificial insemination failed to improve pregnancy risk of lactating dairy cows

 

The relationship between external auditory canal temperature and onset of estrus and ovulation in beef heifers

 

Follicular response and oocyte production following variations in ovarian stimulation in goats

 

Inhibition of apoptosis by caspase inhibitor Z-VAD-FMK improves cryotolerance of in vitro derived bovine embryos

 

Promoter variants of OAS1 gene are associated with reproductive performance and incidence of normal calving in cattle

 

The ability to predict pregnancy loss in cattle with ELISAs that detect pregnancy associated glycoproteins is antibody dependent

 

http://www.sciencemag.org/news/2018/02/first-cow-embryonic-stem-cells-could-lead-healthier-more-productive-livestock

AETA Articles of Interest

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Published on: September 26, 2017

Birth of healthy calves after intra-follicular transfer (IFOT) of slaughterhouse derived immature bovine oocytes

Effects of oocytes exposure to bovine diarrhea viruses BVDV-1, BVDV-2 and Hobi-like virus on in vitro-produced bovine embryo development and viral infection

Relationship between in vitro growth of bovine oocytes and steroidogenesis of granulosa cells cultured in medium supplemented with bone morphogenetic protein-4 and follicle stimulating hormone

Equine chorionic gonadotropin increases fertility of grazing dairy cows that receive fixed-time artificial insemination in the early but not later postpartum period

Effective use of SexedULTRA™ sex-sorted semen for timed artificial insemination of beef heifers

Genetic component of sensitivity to heat stress for nonreturn rate of Brazilian Holstein cattle

Leptin supplementation in vitro improved developmental competence of buffalo oocytes and embryos

2-Methoxystypandrone improves in vitro-produced bovine embryo quality through inhibition of IKBKB

Split-time artificial insemination in beef cattle: III. Comparing fixed-time artificial insemination to split-time artificial insemination with delayed administration of GnRH in postpartum cows

Temporal effect of maternal heat stress during gestation on the fertility and anti-Müllerian hormone concentration of offspring in bovine

Maternal and non-maternal factors associated with late embryonic and early fetal losses in dairy cows

Blood flow and echotextural differences between the future dominant and subordinate follicles before the beginning of diameter deviation in heifers

Comparison of estrus synchronization by controlled internal drug release device (CIDR) and adhesive transdermal progestin patch in postpartum beef cows

Relationship among circulating anti-Müllerian hormone, insulin like growth factor 1, cadmium and superovulatory response in dairy cows

Follicular waves and hormonal profiles during the estrous cycle of carriers and non-carriers of the Trio allele, a major bovine gene for high ovulation and fecundity

Relationships between uterine health and metabolism in dairy cows with different dry period lengths

Insulin during in vitro oocyte maturation has an impact on development, mitochondria, and cytoskeleton in bovine day 8 blastocysts

Ovulation rate, antral follicle count, and circulating anti-Müllerian hormone in Trio allele carriers, a novel high fecundity bovine genotype

Evaluation of in vitro-produced bovine embryos

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Published on: June 30, 2017

2015 CETA/ACTE & AETA JOINT CONVENTION – NIAGARA FALLS, ONTARIO

SESSION: IVP vs IVD EMBRYO EVALUATION

Evaluation of in vitro-produced bovine embryos

Jennifer Barfield, Ph.D.

Animal Reproduction and Biotechnology Lab, Colorado State University, Fort Collins, CO

At the 2014 joint meeting of the American and Canadian Embryo Transfer Associations, I presented a pre-conference symposium on bovine embryo grading in an interactive forum where participants provided real-time feedback on how they would grade embryos of various stages and qualities. One aspect of grading touched on was the difference between in vitro-produced (IVP) and in vivo- derived (IVD) embryos. When asked whether the attendees believed we need separate grading systems for these two types of embryos, the crowd was split with 47% of respondents supporting the development of a new system and 53% believing it is not needed. Here I will review some of the challenges involved with grading IVP and IVD embryos, the implications of these challenges, and propose a method by which researchers and practitioners could collaborate to gather data that can be easily shared and used to develop a concensus on the best guidelines for grading IVP embryos.

(more…)

AETA Articles of Interest

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Published on: June 30, 2017

Relationship between circulating progesterone at timed-AI and fertility in dairy cows subjected to GnRH-based protocols

Lipid profiles of follicular fluid from cows submitted to ovarian superstimulation

Corrigendum to “Reducing treatments in cattle superovulation protocols by combining a pituitary extract with a 5% hyaluronan solution: Is it able to diminish activation of the hypothalamic pituitary adrenal axis compared to the traditional protocol?” [Theriogenology 85 (2016) 914–921]

Downsizing cumulus cell layers to improve cryotolerance of germinal vesicle-stage bovine oocytes

Evaluation of shortened timed-AI protocols for resynchronization of ovulation in multiparous Holstein dairy cows

Effects of rumen-protected methionine and choline supplementation on steroidogenic potential of the first postpartum dominant follicle and expression of immune mediators in Holstein cows

Effects of d-cloprostenol on different layers and regions of the bovine uterus during the follicular and luteal phases

Cryosurvival of in vitro produced bovine embryos supplemented with l-Carnitine and concurrent reduction of fatty acids

Articles of Interest

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Published on: March 21, 2017

Calving distributions of individual bulls in multiple-sire pastures

The effect of Presynch-Ovsynch protocol with or without estrus detection on reproductive performance by parity, and the long-term effect of these different management strategies on milk production, reproduction, health and survivability of dairy cows

Bacterial invasion of the uterus and oviducts in bovine pyometra

Transcriptomic evaluation of bovine blastocysts obtained from peri-pubertal oocyte donors

Embryo production in heifers with low or high dry matter intake submitted to superovulation

Early postpartum administration of equine chorionic gonadotropin to dairy cows calved during the hot season: Effects on fertility after first artificial insemination

(more…)

Evaluation of In Vitro–Produced Bovine Embryos

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Published on: December 9, 2016

by Jennifer Barfield, PhD
Animal Reproduction and Biotechnology Lab, Colorado State University, Fort Collins, CO

At the 2014 joint meeting of the American and Canadian Embryo Transfer Associations, I presented a preconference symposium on bovine embryo grading in an interactive forum where participants provided real-time feedback on how they would grade embryos of various stages and qualities. One aspect of grading touched on was the difference between in vitro–produced (IVP) and in vivo–derived (IVD) embryos. When asked whether the attendees believed we need separate grading systems for these two types of embryos, the crowd was split with 47% of respondents supporting the development of a new system and 53% believing it is not needed. Here I will review some of the challenges involved with grading IVP and IVD embryos, the implications of these challenges, and propose a method by which researchers and practitioners could collaborate to gather data that can be easily shared and used to develop a consensus on the best guidelines for grading IVP embryos.

http://www.aeta.org/docs/Evaluation_of_in_vitro_produced_bovine_embryos.pdf

Articles of Interest

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Published on: December 9, 2016

Ovulation time in suckled beef cows is anticipated by use of low doses of progesterone and temporary calf removal on fixed timed AI protocol

Effects of eCG are more pronounced in primiparous than multiparous Bos indicus cows submitted to a timed artificial insemination protocol

Crocetin improves the quality of in vitro–produced bovine embryos: Implications for blastocyst development, cryotolerance, and apoptosis

Improving the cytoplasmic maturation of bovine oocytes matured in vitro with intracellular and/or extracellular antioxidants is not associated with increased rates of embryo development

Investigations of mammary and uterine blood flow in relation to milk yield, postpartum disease, and pregnancy result in dairy cows

Comparison of two timed artificial insemination system schemes to synchronize estrus and ovulation in Nellore cattle

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Bison Conservation

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Published on: September 13, 2016

Good article on bison conservation from Colorado State University.

Natural birth: Two calves born to NoCo conservation herd

Two Articles of Interest Regarding Kisspeptins

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Published on: September 13, 2016

The role of kisspeptin signalling in the hypothalamic–pituitary–gonadal axis — current perspective

Abstract

The discovery of kisspeptins in the recent past remoulded current understanding of the neuroendocrine axis relating to the regulation of human puberty and reproduction. Kisspeptins have been recognised to act upstream of GnRH and have been shown to play a vital role in the control of the hypothalamic–pituitary–gonadal axis via regulation of gonadotrophin secretion, onset of puberty, and control of fertility. KNDy (kisspeptin/neurokinin-B/dynorphin) neurons have been suggested to modulate GnRH pulsatile secretion, which is required to support reproductive function in both sexes. They have also been involved in mediating both positive and negative sex steroid feedback signals to GnRH neurons and serve as a vital connection between reproduction and metabolic status of the body. When kisspeptin is administered to healthy humans, and in patients with reproductive disorders, it strongly and directly stimulates GnRH and subsequent LH secretion and enhances LH pulse frequency. These observations suggest that kisspeptins are a potential novel therapeutic approach for treating disorders with either pathologically reduced or augmented gonadotrophins pulsatile secretion and is currently a focus of translational research. Kisspeptins have also been identified in several peripheral reproductive organs, indicating their role in modulation of ovarian function, embryo implantation, and placentation, but a great deal of work remains to be done to explore further in this regard, and the evidence is only available from studies done on animal models. In this review we will mainly focus on current available evidence related to the role of kisspeptins in controlling GnRH pulse frequency, specifically their role in puberty, fertility, and reproduction. We will also be appraising other factors that regulate the kiSS1/Kisspeptin/GPR-54 system. (Endokrynol Pol 2015; 66 (6): 534–547) (more…)

Articles of Interest

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Published on: September 13, 2016

3 tips to avoid early embryonic loss in cattle

Dealing with the stubborn corpus luteum during a timed AI program

Proceedings from the 18th ICAR

Steroid hormones in bovine oviductal fluid during the estrous cycle

Effective embryo production from Holstein cows treated with gonadotropin-releasing hormone during early lactation

(more…)

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