Ask a question to an AETA certified ET practitioner

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Published on: February 18, 2021

By Pat Comyn

Ask an ET-related question. An AETA-certified practitioner will answer!

Here’s one I asked Dr. Reuben Mapletoft to answer regarding proper or best thaw temperature for direct thaw (DT) embryos.

Question: Reuben, is there any data that support a 28 to 29°C thaw versus a 35 to 37°C thaw? I see that Japanese papers and the Food and Agriculture Organization of the United Nations recommend 37°C. And how about a 5-s air thaw versus right in bath? It seems to me that cracked zona concerns are a question mark as it hopefully cracks anyhow.

Answer: You are correct; with a direct transfer a cracked zona is probably even preferred. The air thaw is only important for glycerol where it is important to be able to find the embryo.

We looked at several thaw temperatures between 25 and 35°C several years ago and found no difference in survival. I suppose you argue that perhaps you should be thawing near environmental temperature, but I think it is important to thaw quickly. Having said that, thaw rate to 0°C is probably the same for all temperatures, so then the thaw temperature really determines where it ends up.

Reuben J. Mapletoft

Distinguished Professor Emeritus

Department of Large Animal Clinical Sciences

Western College of Veterinary Medicine

University of Saskatchewan Saskatoon, SK S7N 5B4 

Winter is Coming!

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Published on: November 2, 2020

Summer has been a HOT ONE in most places this year. Beware; Mother Nature has a way of balancing things out. The weather forecasters predict a cold winter in the northern United States, and a mild one in the southern United States. These are the same people that only predict a hurricane’s path with any accuracy within 24 hours. Go figure!

You find yourself driving down a snowy road. The wind is howling, and the snow is sideways. The temperature seems to drop every minute. Finally, you reach your destination an hour late. Clients will be coming soon for a long day of aspirations. As you unload all your equipment, set up the lab, you realize that you forgot to turn on your incubator. When you do turn it on, it says negative 10 degrees Celsius.

Aspirations are supposed to start in the next few minutes. What do you do?

The first thing I do is pull out my $15 portable hair blow dryer. Then I style my curly locks perfectly, because I always want to look my best for my clients. My friend and classmate, John Heizer, taught me this. Appearances are everything. John likes to volunteer a lot of hair styling tips. It’s his specialty. Also, you should know he hasn’t had a single hair on his head since we graduated in 1985. Go figure!

After my styling session, I then use the blow dryer to rapidly warm the incubator. The convection effect of the blow dryer will bring any cold incubator up to temperature in a matter of minutes. After warming your incubator, you can use it to drive the condensation off your cold microscope or your ultrasound, and even warm your boots. Ready to go in minutes for a day of client-pleasing aspirations.

Go figure!! Gary R. Hash, DVM

AETA Practice Tip

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Published on: August 13, 2020

So now you can buy that fancy tall stainless steel thermal mug and call it a business expense! These vacuum mugs hold liquid nitrogen (and do so, like a dewar) without the outside getting cold. Great for caning embryos, recaning semen, treating cancer eye, etc.

Tip for Exporting Beef Embryos

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Published on: August 13, 2020

When exporting beef embryos, a lot of the CSS collected semen is done by small bull studs. These outfits often are unfamiliar with embryo export requirements so be sure to check the CSS semen certificate from these centers to ensure that an accredited veterinarian has signed the CSS document. A non DVM, etc, signature is not valid. 

Practice Tips

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Published on: April 6, 2020

Pat Comyn, DVM

1. Always try to obtain straws used in the breeding for a flush to obtain collection date. If the semen is CSS and you’re certified and APHIS inspected, an export opportunity might arise in the future.

2. If a straw label has small print and difficult to read, take a picture and enlarge image.

3. I’ve found that doing procedures, like performing OPU where one really needs an animal to stay still, is greatly eased by administration of 10 mg xylazine with 100 mg ketamine intravenously. This also helps (along with epidural) relieve straining and other things that cows will do while one is attempting a complicated procedure. I prefer doing this as opposed to giving xylazine mixed with a lidocaine epidural; the ketamine seems to provide a more dependable analgesic and sedative effect.

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.


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;

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:

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


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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.

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



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


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


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.


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


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.


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).


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.


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.


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.



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

Legality of Compounded Estradiol for Embryo Transfer

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Published on: July 25, 2019

The AABP office has received questions from members regarding the legality of using compounded estradiol products in cattle for embryo transfer protocols. AABP has also been in discussion with the FDA about the use of compounded estradiol products in food animals. Compounding from approved drugs in animals is only permitted under the narrowly defined conditions outlined in AMDUCA (Section 21 CFR 530.13). To be permitted, extralabel use from compounding of approved animal drugs or approved human drugs must be in compliance with all relevant provisions of 21 CFR 530 (AMDUCA), including the provisions limiting extralabel use to treatment modalities when the health of an animal is threatened or suffering or death may result from failure to treat. The extralabel use regulation also does not provide for compounding from active pharmaceutical ingredients (APIs or bulk drugs—i.e., the raw chemical) for use in animals. Therefore, it is illegal for veterinarians to use or prescribe compounded estradiol for cattle, or any form of estrogenic compounds for production purposes, including embryo transfer and synchronization protocols. AABP encourages cattle veterinarians to refrain from administering or prescribing compounded estradiol for the following reasons:

  • AMDUCA only allows for extralabel drug use when the health of an animal is threatened. There is no production allowance, particularly for compounding; therefore one cannot use human-approved drugs (e.g., ECP, Pfizer) or a different form of an animal-approved drug (e.g., growth-promoting implants) for production purposes.
  • Compounding from a bulk product is specifically prohibited in AMDUCA regulations.
  • The safety, potency, efficacy, stability, sterility, and disposition of compounded products is unknown. Compounded products do not undergo FDA inspection, potency testing, or efficacy testing. Veterinary compounding pharmacies that also compound for humans are under federal regulation and are FDA inspected; however, this only applies to the human side of the compounding operation. Veterinary compounding pharmacies do not have this level of oversight. There is no guarantee of the safety or efficacy of compounded products, and liability for the use of such products falls on the veterinarian in the event of an adverse reaction or violative residue.
  • Because the safety, efficacy, potency, and disposition of the compounded product is not known, it is impossible to assign a withdrawal interval for compounded products.
  • The use of compounded products in food animals places a veterinarian at risk of professional liability.

The need for estradiol for successful embryo transfer protocols has not been unequivocally established. For example, data from nearly 7,000 collections did not demonstrate a difference when using GnRH in place of estradiol in the protocol.1 Additional references are available on the Reproduction Committee page of the website at Veterinarians who engage in federally prohibited activities put themselves at risk and also risk the profession’s reputation for appropriate and judicious oversight of pharmaceutical products in our cattle patients. This is especially of concern when using an unapproved and illegally manufactured hormone product.

AABP Newsletter 5 May 2019.

Please contact Dr. Fred Gingrich at with any questions.

Submitted by the AABP Reproduction Committee and the AABP Committee on Pharmaceuticals and Biologics.

1Hinshaw, R.H. Comparison of GnRH and estradiol 17β for follicle turnover in bovine superovulation protocols. Proceedings of the American Embryo Transfer Association 2013, p. 15.

AETA Small Ruminant Ovum-Pick-Up Brief

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Published on: April 17, 2019

Submitted by Dr. Kevin Lindell

Recently, Dr. Rachael Gately, Tufts Veterinary Field Service, had the opportunity (through a collaborative research project) to explore the realm of small ruminant ovum pick-up (OPU)/in vitro fertilization (IVF).

We thought it would be interesting to the membership to relay our initial experiences and challenges.

To date, donors have been collected after superstimulation, using protocols somewhat similar to those we use in cattle. Without prior manipulation of the estrus cycle, a SR CIDR is placed on day −7. On day 0 donors receive PG and 1.5 cc of follicle-stimulating hormone (FSH) AM/PM; day 1 donors receive 1.0 cc of FSH AM/PM and then 1.0 cc of FSH on the morning of day 2. Oocyte collection is performed on day 4, resulting in a coasting period (time between the last FSH injection and time of collection) of approximately 48 hours. Variables such as FSH dosage, number of total injections, and coasting period seemed to make a significant impact on follicular recruitment, size, and competency, although the data set is very small to this point.

Oocyte collection is performed under general anesthesia using a short-needle system. A threaded small ruminant 18-ga OPU needle, attached directly to aspiration tubing (without using a metal rod) has been a relatively simple and successful method for oocyte collection, in conjunction with our regular aspiration/vacuum pump. Although we would ultimately like to offer small ruminant OPU as a purely laparoscopic procedure, it has been difficult to stabilize the ovaries well enough, so we have instead opted to externalize the ovaries briefly for aspiration.

As this procedure seems to be growing in interest amongst our clientele, we are looking forward to additional small ruminant oocyte collection trials and embryo development results.

The abstract below from a recent review article was also a useful tool as we initially organized equipment, consumables, and donor protocols.

Theriogenology (86) 2016

Recent advances in in vitro embryo production in small ruminants

By Maria-Teresa Paramio*, Dolors Izquierdo


To increase productivity in the small ruminant industry, the genetic material of these species should be improved. In vitro embryo production could be an important technology to reach this goal by combining selected male and female gametes. In the world, marketing of in vitro-produced embryos is an economical activity which is progressing rapidly in cattle but is practically nonexistent in small ruminants. Since the birth of the first lamb and kid using IVF in the 80s, several studies have been carried out; however, results still are inconsistent and unpredictable. Moreover, significantly fewer research groups are working on embryo production in small ruminants than in cattle and pigs. Although conventional methodologies of oocyte IVM, IVF, and IVC in small ruminants give rise to blastocysts, significant variation exists between experiments. One important reason for these differences is the heterogeneity of the pool of oocytes recovered from ovaries from slaughtered females. Oocyte quality, also referred to as competence, is the key factor in the success of in vitro embryo production programs. Different criteria are used to select the best oocytes for fertilization, such as follicle size, oocyte diameter and morphological appearance, and Brilliant Cresyl Blue staining. New research lines aimed at improving oocyte competence are: (1) arresting nuclear maturation in vitro allowing optimal capacitation of cytoplasm, (2) growing oocytes inside the follicle, and (3) identification of biomarkers of oocyte competence in granulosa and cumulus cells and metabolites in the follicular fluid.

Practice Tip – Battery Backup

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Published on: April 17, 2019

Submitted by Dr. Pat Comyn

This jump starter has come in really handy for those times when I am breeding or placing embryos in a place with no power. With all the moisture we have had in my area in the last year (92 inches), it is sometimes really difficult to get a truck near the working area. Also, trucks near the working area = dented trucks. So this gadget is great for keeping the thaw bath warm. It also charges cell phones.  


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: 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.


Practice Tip

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Published on: July 6, 2018

by Pay Comyn
AETA Education Committee Chair

I saw a good reminder of dangers of using frozen cold pacs to chill down fresh transported embryos. A client accidentally froze several syringes of rabies vaccine meant for their cattle by placing the syringes directly on frozen ice packs. So embryo straws with holding solution placed directly on frozen ice packs would be risky. When using frozen ice packs to keep fresh embryos cool, one should place cloth or paper over the ice packs to protect the embryos.

Effects of Ovum Pick‐up Frequency and FSH Stimulation: A Retrospective Study on Seven Years of Beef Cattle In Vitro Embryo Production

Categories: Catching Up, Practice Tips
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Published on: July 6, 2018

Authors: R De Roover, JMN Feuganf, PEJ Bois, G Genicot, Ch Hanzen

Publication: Reproduction in Domestic Animals

Publisher: John Wiley and Sons

Date: Mar 6, 2008


My IVF incubator is late….now what?

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Published on: April 10, 2018

By Jon Schmidt (Trans Ova Genetics)

An unfortunate reality with IVF is the occasional need to utilize commercial shipping companies in the transportation of oocytes to and embryos from the IVF lab.  Many of us who work with IVF shipments have experienced a delayed, lost, or cold incubator.  These are unfortunate events that can be catastrophic to results and end in frustrated lab staff, transfer teams, and clients.  Below are a few suggestions on how to handle incubators that are compromised in transit while embryos are going back to the practitioner or client’s farm.

d0 = OPU day
d1 = fertilization day
d7 = normal transfer day


AETA Practice Tip: Placing CIDR

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Published on: April 10, 2018

By Tyler Dohlman (Iowa State University)

For most of us practitioners, CIDR have become a staple in our reproductive programs and will continue to be as long as they are effective. Whether they are used on donors or recipients or in artificial insemination protocols, they allow us to manipulate the estrous cycle for various needs. However, everyone has had a time when the number of CIDR put in does not match the number found when it comes time to retrieve them. This scenario can happen in a few instances: (1) we did not actually place a CIDR in the first place or (2) they fell out or were pulled out prior. CIDR, in general, should not come out sporadically, and if they do, it is usually because of poor or haphazard placement. Therefore, the latter scenario in which they are getting pulled out is more likely. In our experience, heifers are the problem child group. Heifers, curious in nature, and especially Holsteins, are all too accustomed to making our lives much more difficult by helping us pull CIDR out before our protocol says.

To mitigate this issue, I was taught at some point in my career to clip the blue attached string short. However, I usually forget to grab scissors or a knife to do such modifications to the CIDR at placement. Conveniently enough, I was taught a different modification to hide that all-too-enticing blue string. The modification is simple and easy, and rarely, if ever, do we lose CIDR in those curious Holstein heifers anymore.

If you have ever looked at a CIDR, there is a hole the same size as the blue string on the base of the CIDR. All you have to do is flip the blue string in the hole before placing the CIDR in the applicator. This hides the blue string and conveniently creates a looped handle for removal. In our hands, this modification has worked on our farms with heifers. Clients are less adaptive to this new method because they cannot see the blue string to confirm the CIDR is still in place, but the persuasive nature in me explains that if a CIDR were to fall out prior to protocol, it could prevent an ET or AI pregnancy. Caution: we commonly do this in cows also, and sometimes the blue string handle is in just a little too far and is out of reach. Then trans-rectal palpation guidance is needed to push the CIDR closure to the vulvar opening for retrieval.

On that note, I hope this helps someone and that you never lose another CIDR.

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

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Published on: December 27, 2017

John F. Hasler
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.


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.


The Role of Trace Minerals in Beef Cattle Fertility

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Published on: December 27, 2017

Ratzburg, Cole, The Role of Trace Minerals in Beef Cattle Fertility, M.S., Department of Animal Science, August 2017.

The most important economic factor influenced by trace mineral deficiencies is impaired reproductive performance in both the male and female. Copper (Cu), zinc (Zn), and manganese (Mn) have been shown to improve fertility in male and female beef cattle due to their roles in vitamin synthesis, hormone production, enzyme activity, collagen formation, tissue synthesis, oxygen transport, energy production, and other physiological processes related to growth, reproduction, and health. A new form of trace minerals called hydroxy minerals, which is a hydrolyzed inorganic metal complex, has been shown to have a greater bioavailability than sulfate minerals and similar bioavailability compared with the organic trace minerals. The idea that hydroxy trace minerals could be more available to beef cattle led us to hypothesize that use of hydroxy forms of Cu, Zn, and Mn could improve fertility in male and female beef cattle that are transitioning into the pubertal phase. The objectives of the two studies were to determine whether the use of hydroxy trace minerals could improve fertility parameters related to both the male and female beef cow. Peripubertal bulls were supplemented with hydroxy forms of Cu or Zn or Cu and Zn or no Cu and Zn in an 83-day mineral trial to determine whether there were differences in liver, blood plasma, and semen mineral concentrations and subsequently breeding soundness exam parameters, sperm morphology, and flow cytometer analysis. Results showed the use of Cu and Zn had benefits for fertility; there was improvements in flow cytometer parameters and sperm morphology. Heifers were supplemented with sulfate and hydroxy forms of Cu, Zn, and Mn to determine whether the different forms of trace minerals could affect feed intake parameters such as average daily gain, dry matter intake, residual feed intake, and feed-to-gain ratio and the fertility parameters: percent cycling and percent conception. Results indicated that there were no differences in feed intake parameters between treatments, but there was a positive benefit observed with the hydroxy trace minerals on conception percentage.


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