How much Follicle Stimulating Hormone do we really need for cattle superovulation?

Categories: Evidence-Based ET
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Published on: April 6, 2020

John Gibbons, PhD

Superovulation data
Although the American Embryo Transfer Association and the International Embryo Technology Society perform a tremendous and necessary review of embryo transfer activity in the United States (Tables 1 and 2) and worldwide, there are limited data available on the dose, type, route of delivery, and protocols for Follicle Stimulating Hormone (FSH) administration (Kelly, 1997). Other factors that contribute to the success of ovarian hyperstimulation are the breed, age, parity, and management of cattle, ovarian follicular reserve, and superovulation history of a particular donor. Delivery of FSH to achieve superovulation is generally a twice daily injection schedule beginning on the day before or the day of emergence of a follicular wave (Adams, 1992) and lasting for three or four days; however, single dose (Looney, 1986; Bo, 1994; Kelly, 1997) or split single dose delivery (Tribulo, 2012), as well as FSH gels (Kimura, 2016) and implants (Floyd, 2007) to enhance bioavailability have been reported. The current FDA approved FSH product is a pituitary derivative although the interest in producing a custom, reliable, and effective, FSH (and Luteinizing Hormone [LH]) product from recombinant technology has a substantial history (Looney, 1988; Wilson, 1993) and is gaining considerable traction (Hesser, 2011; Vega, 2019). Classically, pituitary-derived FSH products had substantial LH contamination and a role for each of the gonadotropins was hypothesized (Donaldson, 1985). The current product is very pure although it is likely that some LH might well be important for successful nourishment of multiple dominant follicles (Ginther, 1996) although it may be difficult to mimic the pulsatile pattern of LH. Regardless of the protocol, the most critical component for FSH administration is the timing relative to the endogenous FSH surge. Practically, this approach requires a hormonal or mechanical technique to engineer a follicular wave in order to efficiently schedule the embryo collection (Crowe, 2013. The protocol for engineering a follicular wave also has many considerations and challenges (time, expensive equipment, choice of hormones, etc.).

What if we miss an FSH injection?
The literature is scant with information about which FSH injections are the most important. It seems logical that the first few injections are the most important (due to dosage and timing) and the last few are the least important. Using a six FSH injection protocol following ultrasound guided follicular ablation of all follicles larger than 5 mm, the administration of the sixth FSH injection or not did not impact the embryo recovery results (Gibbons, 2019). Practically, even if it is known that an FSH injection was missed, the donor will still likely be inseminated and embryo recovery attempted. A single dose of FSH administered on Day 10 following estrus has been shown to produce a similar number of ovulations as a multi-dose approach (Kelly, 1997); however, there were more degenerate embryos and unfertilized ova, suggesting that in addition the scheduling aspect, engineering a follicular wave for superovulation may be important impact the “fertilizability” of the ova within the follicles and the timing of the first few FSH injections relative to follicular wave emergence outweighs the effects of any other single FSH injection.

FSH per Transferable Embryo
There is no public data base for the amount of FSH given to any one donor. There are recent data (Gibbons, 2019) to suggest that the amount of FSH per transferable embryo may be as low as 1.5 mls (54 IU; Folltropin) following an engineered follicular wave. The appropriate timing of FSH initiation could decrease the overall required dosage of FSH, which is financially important given that the cost of FSH is one of the largest single costs associated with superovulation. Further, although there is a relatively accurate idea of how many corpora lutea (CL) are present at embryo collection, without counting the CL via ultrasonography, it is difficult to know if or how many embryos / ova are not accounted for following collection.

Where do we go from here?
In vitro embryo technologies are clearly gaining considerable traction (Table 2.); however, the need for effective and efficient superovulation protocols remains important. The effectiveness of these protocols is linked to the timing of the initial FSH injection; however, due to the considerable number of different protocols that are available it is difficult to determine which approach more appropriately exploits the endogenous FSH surge and results in more transferable embryos. Future research comparing different FSH protocols relative to endogenous FSH profiles and follicular wave emergence will be important and may increase the number of transferable embryos per collection which has not waivered substantially in 20 plus years.

References:

Adams GP, Matteri RL, Kastelic JP, Ko JC, Ginther OJ. Association between surges of follicle-stimulating hormone and the emergence of follicular waves in heifers. Journal of Reproduction Fertility, 1992; 94(1):177-188.

Bo GA, Hockley DK, Nasser LF, Mapletoft RJ. Superovulatory response to a single subcutaneous injection of Folltropin-V in beef cattle. Theriogenology, 1994;42(6):963-975.

Crowe MA, Mullen MP. Relative roles of FSH and LH in stimulation of effective follicular response in cattle. Intech Open Access, 2013; http://dx.doi.org/10.5772/50272.

Donaldson LE. LH and FSH at superovulation and embryo production in the cow. Theriogenology 1985;23(3):441-447.

Floyd C. Subcutaneous FSH implants. MS Thesis, Clemson University, 2007: https://tigerprints.clemosn.edu/all_thesis/94.

Gibbons JR, Anton J. Dominant follicle removal prior to superovulation. Poster presented at 2019 joint annual AETA & CETA/ACTE convention, 2019.

Ginther OJ, Wiltbank MC, Fricke PM, Gibbons JR, Kot K. Selection of the dominant follicle in cattle. Biology of Reproduction 1996;55:1187-1194.

Hesser MW, Morris JC, Gibbons JR. Advances in recombinant gonadotropin production for use in bovine superovulation. Reproduction Domestic Animals, 2011;46:933-942.

Kelly P, Duffy P, Roche JF, Boland MP. Superovulation in cattle: effect of FSH type and method of administration on follicular growth, ovulatory response and endocrine patterns. Assisted Reproduction Sciences 1997;46:1-14.

Kimura K. Superovulation with a single administration of FSH in aluminum hydroxide gel: a novel superovulation method for cattle. Journal of Reproduction Development, 2016;62(5):423-429.

Looney CR, Bondioli KR, Hill KG, Massey JM. Superovulation of donor cows with bovine follicle-stimulating hormone (bFSH) produced by recombinant DNA technology. Theriogenology 1988;29:271.

Looney CR. Superovulation in beef females. Proceedings of the 5th annual conference of American Embryo Transfer Association, 1986;16-29.

Tribulo A, Rogan D, Tribulo H, Tribulo R, Mapltoft RJ, Bo GA.
Superovulation of beef cattle with a split-dose intramuscular administration of Folltropin-V in two concentrations of hyaluronan. Theriogenology 2012;77:1679-1685.

Vega VMB, Chavez SPJ, Franco CDM, Ramos TI, Toledo JR. FSH in superovulation. Revista Bionature, 2019;812-816.

Wilson JM, Jones AL, Moore K, Looney CR, Bondioli KR. Superovulation of cattle with a recombinant-DNA bovine follicle stimulating hormone. Animal Reproduction Science, 1993;33(1):71-82.

The effects of zinc on the maturation and fertilization of bovine oocytes

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Published on: April 6, 2020

Brianna M. Price, Taylor F. Mittleider, Kayla Grau, and John Gibbons,
College of Veterinary Medicine, Lincoln Memorial University, Harrogate, TN

Introduction
Zinc is an essential trace mineral in many species, playing many roles including an essential role in reproduction. Zinc is found throughout the body including the brain, kidney, liver, muscle, and bones where it plays a role in RNA and DNA metabolism (Hambridge and Krebs, 2007.) The highest concentrations of zinc are found in the eye and prostate gland (Hambridge and Krebs, 2007.) In the bovine oocyte, zinc is the most abundant transition metal with concentration fluctuations occurring during maturation and fertilization events (Que et al., 2019.) In all organisms examined, an event referred to as the “zinc spark” has been documented as an essential reproductive phenomena (Que et al., 2019.) High concentrations of zinc are present in the female gamete prior to the zinc spark, where zinc is released from the oocyte following intracytoplasmic sperm injection and natural encounters with a sperm cell (Bernhardt et al., 2012; Duncan et al., 2016; Que et al., 2019.) Higher quantities of zinc release during this event has been associated with higher quality embryos (Duncan et al., 2016; Picco et al., 2010; Zhang et al., 2016.) Zinc has been shown to play an important role in DNA stabilization during the fertilization process, when DNA is in a haploid state, including protection from damage and apoptosis (Anchordoquy et al., 2014.) The ability to produce in vitro bovine embryos provides an ideal model to enhance understanding of fertilization events in human reproduction. This studied examined the role of zinc in in vitro maturation and fertilization of bovine oocytes and tested the hypotheses that dose dependent zinc supplementation would enhance oocyte maturation and the chelation of zinc would inhibit fertilization and early embryonic development.

Evaluation of Zinc Supplementation on In Vitro Maturation
Bovine oocytes were obtained via follicular aspiration of postmortem ovaries harvested from an abattoir. Selected oocytes contained at least three layers of cumulus cells and a homogenous cytoplasm. Oocytes were separated into four in vitro maturation treatment groups supplemented with 0, 5, 10, and, 20 μM zinc. Supplementation doses where determined from analysis of zinc concentrations in adult cow plasma and follicular fluid (10.55 μM and 11.47 μM, respectively) and commercial maturation and fertilization medias (1.07 μM for each). Oocytes were considered mature if they had reached Metaphase II and had expelled their first polar body after 18 hours in maturation media. There was no statistical significance found in the maturation rates of the oocytes (78.1 ± 3.0%, 59.5 ± 4.3%, 69.8 ± 7.7%, 62.3 ± 3.2%, respectively). Mature oocytes were statistically analyzed by Chi Square test.

Evaluation of Zinc Chelation on In Vitro Fertilization and Embryo Development
The effects of zinc chelation on fertilization was observed in oocytes matured in 0 μM zinc, fertilized with frozen-thawed bull semen of a characterized bull, and separated into two groups. A zinc chelated group contained 2.7 mM of TPEN (tetrakis(2-pyridinylmethyl)-1-2-ethanediamine) supplemented in the fertilization media compared to non-treated controls. Following fertilization, the presumptive zygotes were cultured in their respective groups for 7 days (no TPEN). Embryonic development to the morula or blastocyst was analyzed by Chi Square test. The TPEN treated group had a statistically lower cleavage rate (p<0.05) than the control group (46.1 ± 2.3% and 75.6 ± 3.4%, respectively). Embryo development rate to morula stage was also statistically lower (p<0.05) in the TPEN treated group compared to the controls (15.4 ± 0.03% and 37.8 ± 0.03%, respectively). The average embryo developmental stage scores analyzed by ANOVA were significantly lower (P<0.001) in the TPEN treated group compared to the controls (2.2 ± 0.1 and 3.4 ± 0.2, respectively).

Conclusion
This study supports the concept that zinc supplementation has minimal effects on in vitro maturation of oocytes; however, removing zinc during in vitro fertilization, significantly decreased cleavage rate and embryo development to blastocyst. Future studies may determine a more precise role of Zinc during sperm penetration and fertilization mechanisms.

References

Anchordoquy, J. M., Anchordoquy, J. P., Sirini, M. A., Picco, S. J., Peral-García, P., & Furnus, C. C. (2014). The Importance of Having Zinc During In Vitro Maturation of Cattle Cumulus-Oocyte Complex: Role of Cumulus Cells. Reprod Dom Anim, 49, 865-874. doi:10.1111/rda.12385

Bernhardt, M. L., Kong, B. Y., Kim, A. M., O’Halloran, T. V., & Woodruff, T. K. (2012). A Zinc-dependent mechanism regulates meiotic progression in mammalian oocytes. Biology of Reproduction, 86(4):114, 1-10. doi: 10.1095/biolreprod.111.097253

Duncan, F. E., Que, E. L., Zhang, N., Feinberg, E. C., O’Halloran, T. V., & Woodruff, T. K. (2016). The zinc spark is an inorganic signature of human egg activation. Scientific Reports, 6,24737. doi: 10.1038/srep24737

Hambridge, K. M. & Krebs, N. F. (2007). Zinc deficiency: a special challenge. Journal of Nutrition, 137(4), 1101-1105.

Picco, S. J., Anchordoquy, J. M., de Matos, D. G., Anchordoquy, J. P., Seoane, A., Mattioli, G. A., Errecalde, A. L., & Furnus, C. C. (2010). Effect of increasing zinc sulphate concentration during in vitro maturation of bovine oocytes. Theriogenology, 74, 1141-1148. doi:10.1016/j.theriogenology.2010.05.015

Que, E. L., Duncan, F. E., Lee, H. C., Hornick, J. E., Vogt, S., Fissore, R. A., O’Halloran, T. V., & Woodruff, T. K. (2019). Bovine eggs release zinc in response to parthenogenetic and sperm-induced egg activation. Theriogenology, 127, 41-48. doi:10.1016/j.theriogenology.2018.12.031

Zhang, N., Duncan, F. E., Que, E. L., O’Halloran, T. V., & Woodruff, T. K. (2016). The fertilization-induced zinc spark is a novel biomarker of mouse embryo quality and early development. Scientific Reports, 6, 22772. doi:10.1038/srep22772

Dominant follicle removal prior to superovulation

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Published on: April 6, 2020

Taylor Mittleider, a Brianna Price, a John Gibbons, a Jason Anton b
a College of Veterinary Medicine, Lincoln Memorial University, Harrogate, TN, b Ovaflo Genetics, Tahlequah, OK

Introduction: Superovulation and embryo collection and transfer enables cattle producers to reach reproductive, financial, and genetic goals. Although knowledge of follicular development has improved, the number of transferable embryos per collection has not, leading to a high degree of unpredictability. Follicular stimulating hormone (FSH) is a major cost of embryo transfer, and administration must occur coincidentally with an endogenous FSH surge for effective superovulation and embryo recovery, which has not improved substantially in many years, possibly due to suboptimal timing of FSH delivery (Adams, 1992). A major source of variability in the superovulatory response in cattle is the status of ovarian follicles at the time of initiation of FSH treatments (Mapletoft, Steward, & Adams, 2002). Following dominant follicle ablation, an FSH surge and associated follicular wave can be predicted and managed, which may lead to more consistent embryo collections and more transferable embryos (Crowe, 2013). The purpose of this field trial was to evaluate dominant follicle ablation prior to superovulation with a minimal dose of FSH.

Methods: Cycling beef cattle, at random stages of the estrous cycle , were subjected to transvaginal ultrasound-guided aspiration of all follicles (> 5 mm). Following aspiration, PGF2a (25 mg) was administered and a CIDR was placed. Approximately 48 hours later, Folltropin-V administration began and was given twice daily (am and pm) for 4 days. On the third day of FSH administration, PGF2a was given again and the CIDRs were removed that evening. Cattle were inseminated at estrus. One week later, embryos were collected and corpora lutea (CL) were counted using transrectal ultrasonography. All data, both pre-recovery and day of recovery, were analyzed statistically using ANOVA.

Results: Neither the number of follicles ablated, nor the diameter of the ablated follicles had any statistical effect on embryo recovery; however, as indicated in Table 1, cattle (n = 24) with a CL < 22 mm at ablation, tended (P = 0.086) to produce fewer transferable quality embryos (mean ± SEM; 5.8 ± 0.7) than cattle (n = 26) with a CL ≥ 22 mm (8.1 ± 1.1) at ablation.

Cattle (n = 35) given ≥ 10 mls of FSH had a similar number of; total ova (11.3 ± 1.3), transferable embryos (6.2 ± 0.9), and CL (14.2 ± 0.9) compared to cattle (n = 28) given < 10 mls of FSH (12.3 ± 1.1, 6.3 ± 0.6, 15.1 ± 1.0, respectively). This approach also facilitated acceptable results from consecutive embryo recoveries (Figure 1).


Conclusion: Dominant follicle removal prior to superovulation, required less exogenous FSH to achieve acceptable embryo recovery results. These results indicated that ablation of follicles (> 5mm) in cycling mid-diestrus beef cattle, prior to initiation of superovulation may yield more consistent embryo production perhaps due to a more tightly synchronized engineered follicular wave. Further characterization of the dynamics of this follicular wave may facilitate more consistent superovulation results and reduce costs.

References:
Adams GP, Matteri RL, Kastelic JP, Ko JC, Ginther OJ. Association between surges of follicle-stimulating hormone and the emergence of follicular waves in heifers. Journal of Reproduction Fertility, 1992; 94(1):177-188.

Crowe MA, Mullen MP. Relative roles of FSH and LH in stimulation of effective follicular response in cattle. Intech Open Access, 2013; http://dx.doi.org/10.5772/50272.

Mapletoft, R. J., Steward, K. B., & Adams, G. P. (2002). Recent advances in the superovulation in cattle. Reproduction, nutrition, development, 42(6), 601–611. https://doi.org/10.1051/rnd:2002046

Articles of Interest

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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3211119/

https://www.annualreviews.org/doi/10.1146/annurev-animal-021419-084010

https://www.animal-reproduction.org/article/5b5a6048f7783717068b468e

https://rep.bioscientifica.com/view/journals/rep/156/1/REP-18-0008.xml

2018 AETA Statistics Committee Report

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Published on: January 3, 2020

2018 Report of the Data Retrieval Committee

What is an early blastocyst? (And does it matter?)

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Published on: January 3, 2020

Written by Dr. Jennifer Barfield

This year at the annual AETA/CETA meeting in Colorado Springs approximately 100 people signed up for a pre-conference symposium on Advanced ET. One of the three sessions was embryo grading where the audience was asked to stage and grade a variety of embryos from both pictures and videos. This is an exercise that we have done at this meeting in the past and it was interesting to revisit some of the same questions. As in the past, I polled the participants in this session to gauge what level of expertise was in the audience. The breakdown according to years of experience was 0-5 (25%), 6-10 (19%), 11-15 (12%), 16-20 (12%), and 21+ (32%).

For many of the questions the results showed a general consensus, but there was one question for which the distribution was not what I expected. The slide below is the question as it was presented to the audience. The embryo photo is from the IETS Bovine In Vivo Ova Tutorial (see p. 85, IETS members can access the document here https://www.iets.org/pubs_educational.asp).

Across all 3 sessions the answers were A 7%, B 54%, C 34%, D 1%, and E 4% with more disagreement in the first and third session than in the second. See Figure 2. In all sessions more people classified this embryo as an early blastocyst but the number of people who classified this a full blastocyst surprised me. I went back to look at the IETS guide and it stated that as the blastocoele of this embryo is approaching 50% of the embryo that this may be considered a stage 6 embryo.

As someone who often teaches students about classifying and grading embryos, the idea that I may have been instructing people incorrectly troubled me. At Colorado State University, I teach that an early blastocyst is one in which there is a blastocoele cavity present that has not yet filled the perivitelline space of the embryo, even if the blastocoele cavity is larger than 50% of the embryo. A full blastocyst is characterized by a blastocoele cavity that touches the zona pellucida on all sides, except for where it touches the inner cell mass, thus there is no PV space. I wondered if perhaps my interpretation of an early blastocyst is the result of a drift in teaching from an earlier time when these definitions were more strictly and/or widely followed. So I broke down the answers for this question according to years of experience thinking that perhaps practitioners who were learning how to classify embryos when the guidelines were developed would adhere to them more strictly, i.e. more often calling an embryo like this a full blastocyst. That wasn’t the case.

Of the respondents who had over 20 years of experience, 69% classified this embryo as an early blastocyst (24/35) while 52% of the youngest cohort classified this embryo as early (14/27). The only group in which more people called this a blastocyst than an early blastocyst was the 11-15 years group, although there were few respondents overall in this group (8/13 called this a blastocyst). So, I was wrong about the oldest yet wisest of us following the IETS staging guidelines more strictly.

That led me to ask the question, does it even matter if we are all calling this embryo an early blastocyst or a blastocyst? If you are collecting and transferring day 7 in vivo-produced embryos, probably not. The pregnancy rates from transferring grade 1 early blastocysts and grade 1 blastocysts are not significantly different (Hasler, 2001). This slight difference in stage would not change the synchrony of the recipient you choose. It would likely not change how you would cryopreserve this embryo as most in vivo embryos are slow frozen rather than vitrified. From a research standpoint we often make distinctions in stage depending on the question being asked, so it’s possible that inconsistencies in classifying embryos in the field could yield some erroneous conclusions, although I’ll admit I cannot give you any examples of this as I have not scoured the literature for papers where there were significant differences in outcome between early blastocysts and blastocysts for any tested hypothesis.

Outside of simply desiring consistency, the only time when the decision to call it an early blastocyst verses a blastocyst may be important is when grading in vitro-produced embryos. Grading embryos is not only based on the physical appearance of the embryo but also on its stage of development. The slide below was also discussed during the embryo grading sessions in the context of how to incorporate stage into overall embryo grade. In vitro-produced embryos are approximately 1 day more advanced in development than in vivo-produced embryos because of what we consider day 0 in these 2 systems (in vivo day 0 = standing heat, in vitro day 0 = initiation of co-incubation of sperm and oocytes). All morulae would be a day behind in development in an IVP system and given a grade 2 no matter how perfect but early blastocysts sit on the fence. Grading may be an instance where the > or < 50% blastocoele volume distinction matters with embryos with <50% of the volume being the blastocoele cavity being grade 2 and those with >50% volume being blastocoele grade 1. Still, I would be surprised if this fine distinction and difference in grade would translate into a significant difference in pregnancy rates, which is what matters. If anyone has data that may provide insight, please share it! 

So does it matter if we are all calling this small subset of embryos early blastocysts or blastocysts? Probably not, at least not for in-vivo produced embryos. Is it interesting? I think so, particularly from an educational and research perspective. Is it something that we as a community of reproductive practitioners and embryologists should talk more about as we consider developing a separate grading system for in vitro-produced embryos? I’d say yes.

How much Follicle Stimulating Hormone do we really need for cattle superovulation ?

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Published on: January 3, 2020

Superovulation data

Although the American Embryo Transfer Association and the International Embryo Technology Society perform a tremendous and necessary review of embryo transfer activity in the United States (Tables 1 and 2) and worldwide, there are limited data available on the dose, type, route of delivery, and protocols for Follicle Stimulating Hormone (FSH) administration (Kelly, 1997).  Other factors that contribute to the success of ovarian hyperstimulation are the breed, age, parity, and management of cattle, ovarian follicular reserve, and superovulation history of a particular donor.  Delivery of FSH to achieve superovulation is generally a twice daily injection schedule beginning on the day before or the day of emergence of a follicular wave (Adams, 1992) and lasting for three or four days; however, single dose (Looney, 1986; Bo, 1994; Kelly, 1997) or split single dose delivery (Tribulo, 2012), as well as FSH gels (Kimura, 2016) and implants (Floyd, 2007) to enhance bioavailability have been reported.  The current FDA approved FSH product is a pituitary derivative although the interest in producing a custom, reliable, and effective, FSH (and Luteinizing Hormone [LH]) product from recombinant technology has a substantial history (Looney, 1988; Wilson, 1993) and is gaining considerable traction (Hesser, 2011; Vega, 2019).  Classically, pituitary-derived FSH products had substantial LH contamination and a role for each of the gonadotropins was hypothesized (Donaldson, 1985).  The current product is very pure although it is likely that some LH might well be important for successful nourishment of multiple dominant follicles (Ginther, 1996) although it may be difficult to mimic the pulsatile pattern of LH.  Regardless of the protocol, the most critical component for FSH administration is the timing relative to the endogenous FSH surge.  Practically, this approach requires a hormonal or mechanical technique to engineer a follicular wave in order to efficiently schedule the embryo collection (Crowe, 2013.  The protocol for engineering a follicular wave also has many considerations and challenges (time, expensive equipment, choice of hormones, etc.).

What if we miss an FSH injection?

The literature is scant with information about which FSH injections are the most important.  It seems logical that the first few injections are the most important (due to dosage and timing) and the last few are the least important.  Using a six FSH injection protocol following ultrasound guided follicular ablation of all follicles larger than 5 mm, the administration of the sixth FSH injection or not did not impact the embryo recovery results (Gibbons, 2019).  Practically, even if it is known that an FSH injection was missed, the donor will still likely be inseminated and embryo recovery attempted.  A single dose of FSH administered on Day 10 following estrus has been shown to produce a similar number of ovulations as a multi-dose approach (Kelly, 1997); however, there were more degenerate embryos and unfertilized ova, suggesting that in addition the scheduling aspect, engineering a follicular wave for superovulation may be important impact the “fertilizability” of the ova within the follicles and the timing of the first few FSH injections relative to follicular wave emergence outweighs the effects of any other single FSH injection.

FSH per Transferable Embryo

There is no public data base for the amount of FSH given to any one donor.  There are recent data (Gibbons, 2019) to suggest that the amount of FSH per transferable embryo may be as low as 1.5 mls (54 IU; Folltropin) following an engineered follicular wave.  The appropriate timing of FSH initiation could decrease the overall required dosage of FSH, which is financially important given that the cost of FSH is one of the largest single costs associated with superovulation.  Further, although there is a relatively accurate idea of how many corpora lutea (CL) are present at embryo collection, without counting the CL via ultrasonography, it is difficult to know if or how many embryos / ova are not accounted for following collection. 

Where do we go from here?

In vitro embryo technologies are clearly gaining considerable traction (Table 2.); however, the need for effective and efficient superovulation protocols remains important.  The effectiveness of these protocols is linked to the timing of the initial FSH injection; however, due to the considerable number of different protocols that are available it is difficult to determine which approach more appropriately exploits the endogenous FSH surge and results in more transferable embryos.  Future research comparing different FSH protocols relative to endogenous FSH profiles and follicular wave emergence will be important and may increase the number of transferable embryos per collection which has not waivered substantially in 20 plus years.

References:

Adams GP, Matteri RL, Kastelic JP, Ko JC, Ginther OJ.  Association between surges of follicle-stimulating hormone and the emergence of follicular waves in heifers.  Journal of Reproduction Fertility, 1992; 94(1):177-188.

Bo GA, Hockley DK, Nasser LF, Mapletoft RJ.  Superovulatory response to a single subcutaneous injection of Folltropin-V in beef cattle.  Theriogenology, 1994;42(6):963-975.

Crowe MA, Mullen MP.  Relative roles of FSH and LH in stimulation of effective follicular response in cattle.  Intech Open Access, 2013; http://dx.doi.org/10.5772/50272.

Donaldson LE.  LH and FSH at superovulation and embryo production in the cow.  Theriogenology 1985;23(3):441-447.

Floyd C.  Subcutaneous FSH implants.  MS Thesis, Clemson University, 2007: https://tigerprints.clemosn.edu/all_thesis/94.

Gibbons JR, Anton J.  Dominant follicle removal prior to superovulation.  Poster presented at 2019 joint annual AETA & CETA/ACTE convention, 2019.

Ginther OJ, Wiltbank MC, Fricke PM, Gibbons JR, Kot K.  Selection of the dominant follicle in cattle.  Biology of Reproduction 1996;55:1187-1194.

Hesser MW, Morris JC, Gibbons JR.  Advances in recombinant gonadotropin production for use in bovine superovulation.  Reproduction Domestic Animals, 2011;46:933-942.

Kelly P, Duffy P, Roche JF, Boland MP.  Superovulation in cattle: effect of FSH type and method of administration on follicular growth, ovulatory response and endocrine patterns.  Assisted Reproduction Sciences 1997;46:1-14.

Kimura K.  Superovulation with a single administration of FSH in aluminum hydroxide gel: a novel superovulation method for cattle.  Journal of Reproduction Development, 2016;62(5):423-429.

Looney CR, Bondioli KR, Hill KG, Massey JM.  Superovulation of donor cows with bovine follicle-stimulating hormone (bFSH) produced by recombinant DNA technology.  Theriogenology 1988;29:271.

Looney CR.  Superovulation in beef females.  Proceedings of the 5th annual conference of American Embryo Transfer Association, 1986;16-29.

Tribulo A, Rogan D, Tribulo H, Tribulo R, Mapltoft RJ, Bo GA. 

Superovulation of beef cattle with a split-dose intramuscular administration of Folltropin-V in two concentrations of hyaluronan.  Theriogenology 2012;77:1679-1685.

Vega VMB, Chavez SPJ, Franco CDM, Ramos TI, Toledo JR.  FSH in superovulation.  Revista Bionature, 2019;812-816.

Wilson JM, Jones AL, Moore K, Looney CR, Bondioli KR.  Superovulation of cattle with a recombinant-DNA bovine follicle stimulating hormone.  Animal Reproduction Science, 1993;33(1):71-82.

Articles of Interest

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Published on: January 3, 2020

The pre-hatching bovine embryo transforms the uterine luminal metabolite composition in vivo

Somatic cell nuclear transfer alters peri-implantation trophoblast differentiation in bovine embryos

Placental development during early pregnancy in sheep: Effects of embryo origin on vascularization

Bovine Fetal Placenta During Pregnancy and the Postpartum Period

Heifer nutrition during early- and mid-pregnancy alters fetal growth trajectory and birth weight

Reduced quality of bovine embryos cultured in media conditioned by exposure to an inflamed endometrium

Pivotal periods for pregnancy loss during the first trimester of gestation in lactating dairy cows

Evaluation of the uterine environment early in pregnancy establishment to characterise cows with a potentially superior ability to support conceptus survival

Cryptorchidism

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Published on: October 11, 2019

Written by Dr. Pat Comyn

I have recently had a client ask me what his options were with a holstein bull calf of very high genetic value (genomic prediction) that happened to be a unilateral cryptorchid. Aside from a grunt, I didn’t know how to answer, so I thought I should educate myself. As it turns out, the causes of crytorchidism in cattle aren’t  very well understood. A some observations from some reading.

  1. The left testicle is most commonly affected.
  2. Male repro tract development occurs from a different tissue (wolffian duct which is part of the mesonephros developing into the epididymis, vas deferens, seminal vesicle, and ejaculatory duct) than the female tract (Müllerian duct which differentiates into vagina, cervix, uterus etc).
  3. While many argue that chryptorchidism is “heritable”, the heritability of this trait is not well characterized meaning that we don’t know what percent of the development of cryptorchid syndrome is truly genetic and what percent is environmental (meaning uterine / maternal hormonal influence).
  4. This is an excerpt from Cryptorchidism and associated problems in animals1 R. P. Amann2 and D. N. R. Veeramachanen: Animal Reproduction and Biotechnology Laboratory Colorado State University, Fort Collins, CO 80523-1683 USA.

“Early reports on cryptorchidism (e.g., de Graaf, 1668) provided evidence of two or more diseases, because undescended testes are not located at a common non-scrotal site. Nevertheless, the general perception had been that cryptorchidism is a single disease with moderate heritability, incomplete penetrance, expressed only in males (sex specific expression), and concentrated by inbreeding or minimized by culling affected males and all siblings. However, the notion of a single-locus gene problem gave way to acceptance of a polygenic recessive model, based on relatively small studies with pigs (Sittmann and Woodhouse, 1977; Rothschild et al, 1988) and dogs (Cox et al, 1978; Nielen et al., 2001); also data for men (Czeizel et al., 1981). It is evident that abnormalities in >20 genes are associated with human cryptorchidism (Klonisch et al., 2004) and, currently it is accepted that cryptorchidism has many causes including genetic, epigenetic, and environmental components.”

  1. A search on line showed no studies where back breeding of cryptorchids to dam or siblings had been done to characterize heritability coefficient.
  2. A unilateral cryptorchid will on average produce 60 – 80% the spermatozoa of a normal bull.
  3. The affected testicle should be removed so not to place abnormal spermatozoa in the ejaculate. Too, removal will enhance hypertrophy of the normal testicle.

So here we are. A unilateral cryptorchid dairy bull calf. The owner vents his / her frustration and also inquires as to your thoughts on how to proceed. Here are my thoughts…

  1. If a dairy bull and high enough genomics, offer him out. There are dairy bulls in collection now that are unilateral cryptorchids.
  2. Consider private CSS EU qualified collection then see if the semen can be purchased by a bull stud and sold.
  3. Like point B except the producer sells the semen.
  4. The money might not be as good as a normal bull purchase but one can make lemonade from lemons.

Recap: AETA/AASRP 2019 Small Ruminant Embryo Transfer Seminar

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Published on: July 26, 2019

The AETA/AASRP 2019 Small Ruminant Embryo Transfer Seminar was held June 19 to 22, 2019, at The Ohio State University Large Animal Services satellite veterinary teaching hospital in Marysville, Ohio. The meeting was organized by Dr. Eric Gordon.

The course started on Wednesday, June 19, with a review of small ruminant reproductive physiology by Dr. Sherri Clark. Dr. Bill Croushore and Dr. Dave Dixon discussed embryos processing, grading, and cryopreservation. Drs. Mattes and Shipley discussed embryo collection, anesthesia, and sync methods as well as more reproductive physiology and handling of semen. Later in the day, a goat was surgically flushed as a demonstration.

On Thursday, June 20, and Friday, June 21, course participants broke out into teams of three and flushed three goats or sheep each day. All flushing occurred under gas anesthesia. After each flush, the teams searched embryos, and viable embryos were cryopreserved. Later in the day, Dr. Shipley discussed semen collection and cryopreservation. He also elaborated on reproductive physiology. On Saturday, June 22, teams of three practitioners each laparoscopically inseminated three ewes.

The meeting went very well, and it is felt that participants were quite satisfied with the value of this course. Dr. Eric Gordon at OSU CVM at Marysville deserves a huge thank you for his efforts in bringing this course together and in convincing clients to provide animals to flush. Dr. Justin Kieffer with OSU Animal Science was a huge help in bringing in his technician staff and in assisting with planning for animal usage in this CE meeting and for providing, via the animal science department, some of the animals used.

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

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Published on: July 26, 2019

Read full article here

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

Comparison of iSperm to current accepted methods for raw semen analysis

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Published on: April 17, 2019

Download the poster

New Module on Frozen Semen Evaluation Available

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Published on: December 27, 2018

The AETA Education Committee has partnered with Brad Stroud, DVM, and is pleased to announce that a new educational module is available to AETA members.

To access the new Frozen Semen Spot Test, please log in to the AETA site and follow this link: https://www.aeta.org/edu-teaching-module-frozen-semen.asp. You can view the module in your browser, on your phone, or download it (it is a large file).

Thank you to Brad Stroud, DVM.

 

8 Questions You May Have About Cryopreserving Bovine In Vivo–Derived Embryos

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Published on: December 27, 2017

John F. Hasler
Jfhasler05@msn.com
John.hasler@vetoqinol.com
Cell: 970-222-5302

Dr. Pat Comyn, the new chair of the AETA Education Committee, asked me to write a short piece clarifying some issues concerning the cryopreservation of bovine embryos for inclusion in the December issue of A Closer Look. The AETA has come a long way since our humble beginnings in 1983, and our 2017 membership now totals 556, including a large increase in the number of new members. The following facts and suggestions will be of most interest to our new and less experienced members. Not only are there many variables involved in successfully freezing and thawing bovine embryos, there also are many variations on most of the steps that do not notably detract from success rates. Having worked with many ET practitioners in 17 different states and a number of foreign countries, I have a pretty good idea of what works well and what does not. The following points are either based on published data that I deem to be replicable or based on my own experience and observations. Please feel free to contact me should you want advice or clarification.

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VitaFerm Article: Preparing Cows for Embryo Transfer

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Published on: December 27, 2017

Prepare Cows for Embryo Transfer

Embryo transfer (E.T.) is an important tool to propagate outstanding genetic influence within the herd, with the potential to produce multiple offspring of the same mating in the same year. Because of the time, labor and expense involved in creating these genetics, we reached out to Trans Ova Genetics, a leader in reproductive technologies, to provide useful information to prepare your cows for a successful E.T. program.

According to Trans Ova, successful E.T. programs require intensive management and attention to detail. The results you achieve are highly variable and the level of success is based on your ability to manage all aspects of the operation.

Get Your Recips Ready

Preparing recipient cows for their role of carrying and growing the embryo is not a lot different than preparing cows to be bred naturally. You want to keep them in a low-stress environment, be consistent in daily management practices, give all vaccinations prior to estrus and make sure their nutrition program is supplemented with high levels of trace minerals like copper, zinc and manganese that impact reproductive success.

“Nutrition is without a doubt one of the most important areas of donor and recipient management,” said Jon Schmidt, DVM and Chief Operations Officer at Trans Ova. “First of all, I believe the nutritional management of your cattle needs to be a year-long process. Attention should be placed on meeting their demands for the entire season including gestation and lactation.”

The most critical and demanding time however, includes the month before calving through the first three to four months after calving. This is the most stressful and nutritionally demanding time to allow that cow to produce a healthy calf via colostrum production, begin lactation to raise that calf and become pregnant.

Reproduction is not an essential process in survivability of that cow, and consequently suffers first if nutritional needs are not met. Maintenance and milk production will partition available energy supplies with reproduction suffering at their expense. Therefore, it is critical to meet their requirements. Ensure cows are fed a high-quality mineral especially one that optimizes zinc, selenium and copper as they are critical for successful embryo transfer outcomes. Avoid rations that are high in distiller’s byproducts or sulfur-containing forages. Avoid diets high in Urea.

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Ultrasonography and Embryo Transfer Workshops at the University of Saskatchewan

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Published on: March 21, 2017

Ultrasonography and Embryo Transfer Workshops are being conducted in tandem May 7 – 12, 2017 at the Western College of Veterinary Medicine, University of Saskatchewan with the intention of providing essential knowledge and hands-on experience for veterinary practitioners, research scientists and graduate students. The Ultrasound Workshop is a two and a half-day course covering principles of ultrasonography and equipment operation and imaging, imaging of the reproductive tract in large animals, and OPU/IVF. The Embryo Transfer Workshop is a three and a half-day course covering all aspects of embryo transfer technology in cattle.

Principal instructors for the Ultrasonography Workshop are Drs. Gregg Adams and Jaswant Singh and principal instructors for the Embryo Transfer Workshop are Drs. Reuben Mapletoft, Marcos Colazo, Gregg Adams and Jaswant Singh. Both workshops will involve lectures and hands-on lab sessions. Participants may register for one or both of the workshops, or for individual days.

For more information, contact Reuben Mapletoft (reuben.mapletoft@usask.ca), tel: (306) 222-6152, or Gregg Adams (gregg.adams@usask.ca), tel: (306) 966-7411.

To register contact: Jackie Bahnmann (Jackie.bahnmann@usask.ca), tel: (306) 966-7108, fax: (306) 966-8747.

http://www.usask.ca/wcvm/news_events/events/conferences/wcvm-ultrasound-and-embryo-transfer-workshops.php

Ask John: Question on freezer malfunction

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Published on: September 13, 2016

By John F.Hasler

A few years ago I was asked to change my newsletter column from “Ask John” to “Evidence Based ET”.  However, for this Sept. 2016 edition we are back to some questions submitted to me for which there are not really any hard data available.

For our younger members, some background on my experience in freezing embryos follows. In 1977, my first year out in commercial ET practice after finishing my post-doc at CSU, I flew to Cambridge, England and met with Dr. Steen Willadsen. One year earlier in 1976, Steen had published a paper that described freezing sheep embryos followed by the production of pregnancies after the embryos were thawed and transferred. This followed the first report of successful freezing of mammal embryos (mice) in 1972 by Whittingham, Leibo and Mazur. During my visit to Cambridge, Steen showed me how to make ampules from glass tubing and how to make freezing medium containing DMSO as the cryoprotectant.  I came home enthusiastic and optimistic, but spent a couple of very frustrating years with ampules blowing up not infrequently upon at thawing and very few embryos appearing to survive. We finally gave up on slowing lowering the ampules into the neck of a liquid nitrogen tank and Alan McCauley and I paid $12,000 (equivalent to about $30,000 in today’s dollars) for a Planer freezer.  However, we still had to make our own freezing media and the recommended freezing program was over 3 hours long.  Lastly, the biggest mistake we made for several more years was to transfer the very best embryos into available recipients and freeze what was left, often late at night after we returned to home base.  That old Planer freezer was much too big and unwieldy to haul around from farm to farm.

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Recipient Management and Synchronization: A Veterinarian’s Perspective

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Published on: December 16, 2015

by Pat Comyn, Madison, VA

 

Introduction

Successful embryo transfer comprises two somewhat independent components. The first component is to produce or recover grade and select embryos for immediate placement or cryopreservation. The second component is to transfer the selected fresh or frozen embryos into fertile recipients and obtain viable pregnancies and eventually calves.

This section will focus on the second component, primarily recipient selection and management and use of appropriate protocols to match a recipient’s endometrium with the chronological age of the embryo being transferred.

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Evidence-based ET: What is the best protocol for cryopreserving IVF-derived bovine embryos?

Evidence-based ET: What is the best protocol for cryopreserving IVF-derived bovine embryos?

John F. Hasler

Note: The title of this column was suggested by our AETA board of directors

There has been concern regarding the best way to cryopreserve bovine IVF-derived embryos ever since commercial in vitro embryo production (IVP) started in the early 1990s. Donors in the early days were primarily infertile, problem donors, and annual IVP embryo production in the United States was limited to a few thousand embryos, at most. Production of IVP embryos has increased substantially in recent years, and in 2013, it was reported that 48,112 embryos were produced from OPU collections compared with 301,671 in vivo embryos collected from superovulated cattle. Thus, 13.8% of the total embryos produced were from IVF procedures and 55% of them were reported to have been frozen. It is anticipated that reported IVP production will be substantially higher in 2014. Understandably, the companies providing IVF services are reluctant to share details of their cryopreservation services. However, because fresh IVP embryos are often shipped overnight to ET practitioners/donor owners for transfer on-farm, embryo numbers sometimes exceed the number of available recipients. Consequently, not infrequently, practitioners are faced with cryopreserving leftover IVP embryos. Even today, however, there does not seem to be any widely agreed upon, best protocol for cryopreserving IVP embryos. In the last few years it has been publically reported that IVP embryos have been commercially cryopreserved by vitrification and slow freezing with both ethylene glycol (EG) and glycerol used as the cryoprotectants.

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Evidence-based ET: What is the best synchrony between IVP embryos and recipients?

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Published on: September 10, 2014

Evidence-based ET

John F. Hasler

Note: I have been using subjects suggested by our board of directors for this column for the past two years.  I would be happy to attempt covering any subjects that the membership might suggest. Let me hear from you!

What is the best synchrony between IVP embryos and recipients?

There is a great deal of evidence that synchrony between the age of in vivo-derived embryos and the day of the estrous cycle in recipients at the time of transfer is affected very little, if at all, when synchrony is within the three day period of 0, plus one or minus one day (zero, meaning day of estrus and age of embryo are the same).  Consequently, the pregnancy rate is not affected when day 7 embryos are transferred into day 6, 7, or 8 recipients.  This holds true for both fresh and frozen in vivo-derived embryos (Hasler, 2001).

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