AETA President’s Report – Winter 2021

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Published on: December 20, 2021

Paul Harvey is reported to have said, “In times like these, it helps to recall that there have always been times like these.” Though the challenges may seem different than those in the past, there are challenges nonetheless. Heavy workload, supply chain problems, COVID fears, and labor shortages have left many of us wondering how we can take a breath. At the same time, industry consolidation creates a dark cloud of uncertainty about the future.

Some of the many things I love about the AETA and its members are the camaraderie and the willingness of members to lend a hand to each other, whether it be helping with a technical problem, lending supplies, or referring a client to another practitioner when the book gets full. It is that spirit of cooperation that is good for business in the long term, even if it subtracts from the bottom line in the short term.

I congratulate Dr. Matt Barton and Dr. Lee Jones on their election to the Board of Directors. I also wish to thank both of them and also Dr. Darren Statler and Dr. Alan Strecker for running for that position. One of my duties for 2022 will be to chair the Nominations Committee, which, as part of its charge, will identify potential candidates for the next Board of Directors. If you desire to be on the ballot or know of someone that would make a good board member, please reach out to me.

I also thank Dr. Matt Dorshorst upon his departure from the board for his time on the board and Executive Committee and also Dr. Jeremy VanBoening for his service to the AETA through the Board of Directors. The association is better because of both of them. I am looking forward to my role as past president with the new Executive Committee of Dr. Clay Breiner, president; Dr. Greg Schueller, vice president; and Dr. Daniela Demetrio, secretary-treasurer.

Still, we have work to do to maintain the standing of the AETA in the embryo transfer world here in the United States. To maintain the high standards the industry demands and deserves, we have to keep in mind our purpose:

  • To present a unified voice of the industry to promote the mutual interests and ideals of its members;
  • To protect the users of the embryo transfer industry to the extent technically and ethically possible;
  • To educate the public properly on the status and capability of the United States embryo transfer industry; and
  • To encourage others to engage in the pursuit of this industry.

To achieve our purpose, we need to keep before us the means to fulfil it, namely education and certification. In the coming year, we will continue to explore the prospect of recognizing practitioners only engaged in the transfer of embryos (and not collections) as a means to raise the bar for the industry. Although it will be a type of certification for the transfer of embryos into recipients, it is not likely to be called “certification” to avoid confusion with the comprehensive ET Certification program already in place within the association. We will engage the membership as this initiative progresses.

Dr. Greg Schueller is already at work with the Convention Committee in assembling an outstanding program for Louisville, 2022. Although the virtual conventions provided education and made us better practitioners, the friendships and person-to-person interaction were sorely missed. That will resume in 2022. The Education Committee is working on developing a speaker’s bureau to provide speakers to allied veterinary and industry groups wishing to learn more about the practice of embryo transfer. This will be a longer-term project, and I look forward to seeing it develop.

Finally, I need to thank the membership for allowing me the opportunity to steward this association during the past year. My only hope is that I left the association as good as it was before I joined the board. I am grateful for the many friends I have made during my tenure, and while my time on the board is coming to an end, those friendships are not.

Fight the good fight,


Dr. Bill Croushore – AETA President 2021

Thank You to the 2021 Annual Meeting Sponsors

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Published on: December 20, 2021

AETA would like to extend a special thank you to the 2021 AETA-CETA/ACTE convention sponsors.






The AETA Announces 2022 Board of Directors

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Published on: December 20, 2021

Champaign, IL, December 2021 – The 2021 Annual Meeting of the American Embryo Transfer Association was held October 15 and 16. More than 400 national and international attendees came together virtually to learn more about the most recent advances in advanced bovine reproductive procedures and technology.

The incoming 2022 AETA Board of Directors is listed below.

Board of Directors

President – Dr. Clay Breiner, Westmoreland, KS

Vice President – Dr. Greg Schueller, Whitewater, WI

Secretary-Treasurer – Dr. Daniela Demetrio, Riverdale, CA

Immediate Past President – Dr. William Croushore, Berlin, PA

Director – Dr. Pat Comyn, Madison, VA

Director – Dr. Brad Lindsey, Midway, TX

Director – Dr. Charles Gue, Belgrade, MT

Director – Dr. Matthew Bartlett, Sioux Center, IA

Director – Dr. Lee Jones, Tifton, GA

In addition, the AETA announces its 2022 joint annual convention with the Canadian Embryo Transfer Association (CETA), to be held from October 27-29, 2022 in Louisville, KY

The purpose of the AETA is to unite those organizations and individuals in the United States engaged in the embryo transfer industry into an affiliated federation operating under self-imposed standards of performance and conduct. Members aim to present a unified voice of the industry to promote the mutual interests and ideals of the members; to protect the users of the embryo transfer industry to the extent technically and ethically possible; to educate the public properly on the status and capability of the United States embryo transfer industry; and to encourage others to engage in the pursuit of this industry. For more information about the AETA, please visit

Veterinary School Update: Texas Tech University – School of Veterinary Medicine (TTU-SVM)

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Published on: December 20, 2021

The inaugural veterinary class of the Texas Tech University – School of Veterinary Medicine (TTU-SVM) has completed their first semester at the new campus in Amarillo Texas.  The new building, located on the campus of the Texas Tech University Health Science Center, contains 190,000 square feet of teaching and research space complete with two 100-seat active learning classrooms, a 400-seat auditorium as well as many break out rooms, faculty offices, spaces for up to 100 graduate students, conference rooms, and student study rooms.  The research laboratory spaces average about 2,000 square feet.  There is also an 80,000 square foot teaching and research station just a few miles from the main building that houses resident cattle and horse herds and can accommodate many different species as needed. 

The curriculum is very “hands on” and reflects the interests of animal producers in the region and our more than 60 corporate partners throughout Texas that will serve as mentors and educators for the students in their clinical year of the 4-year distributive program.  Although there are only “first years” on campus currently, Drs. Philippa Gibbons (BVetMed(Hons) MS DACVIM(LA) MRCVS DipVetEd) and Jennifer Koziol (DVM, MS, DACT) are developing the course work that will provide some of the clinical basis for the student’s education and readiness to become Day 1 ready large animal veterinarians.  As part of the large animal curriculum, reproduction will be a focal point as stated by Drs. Gibbons and Koziol: “Students at TTU will be well versed in common food animal reproductive procedures upon completion of the program. Students will begin to perform transrectal palpations in cattle in their 1st year and continue throughout their curriculum. Evaluation of semen is scheduled to begin in the 2nd year and will continue into the 4th year when students can participate in bull breeding soundness exam electives. The hope is to graduate veterinarians that are practice-ready and ready to return to their rural and regional communities and serve the livestock industry”

Courses on embryo transfer and other assisted reproductive techniques will also be a portion of the elective curriculum.  The primary focus of the TTU-SVM is to produce veterinarians that are suited to provide veterinary services for the area of west Texas and beyond as reflected in our mission statement: “Providing high-quality, affordable veterinary medical education that emphasizes One Health principles and general veterinary practice in rural and regional communities across major domestic species”.  This unique opportunity is not lost on the veterinary students as stated by Randal Howard (Class of 2025) “Our program focuses on ‘practice ready veterinarians’ as is evident by our curriculum.  Within the first couple of weeks, we were beginning to perform physical exams on small animals and cattle”. 

Many of the students in the inaugural class are from rural and regional communities and understand the “necessity of having a solid, reliable veterinary practice close by” and “recognize the importance of having a veterinarian familiar with the goals of the respective industries in the area” according to Kayla Wallace (Class of 2025).  Many of the students come to TTU-SVM with considerable experience in agriculture and livestock in particular.  There are also potentially, several budding embryo transfer practitioners in the mix as indicated by Dalton Deckert’s (Class of 2025) experience “I worked for an embryologist and bovine reproductive specialist for two years while I was an undergraduate student, and I was involved in IVF, conventional embryo collections, and artificial insemination in cattle and goats as well as semen collection from bulls”.  The focus on producing practice ready veterinarians to provide services for rural and regional communities in west Texas and beyond is also reflected by our core values of Community, Integrity, Kindheartedness, Grit, and Inspiration.  For more information about the TTU-SVM please visit:

Veterinary School Update: University of Arizona College of Veterinary Medicine

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Published on: December 20, 2021

The University of Arizona College of Veterinary Medicine is a new program that breaks the mold of traditional veterinary medicine curriculum. Our first six semesters are dedicated to learning about different organ systems. Courses are formatted for students to learn about multiple disciplines associated with each system and the uniqueness of the system in each species. In addition, students have clinical skills and professional skills courses with topics that build on the current organ system being studied.

During the courses, students have many opportunities to learn about large animal medicine in addition to companion animal medicine. During the GI course, students learn the differences between ruminant, hind gut fermenters, and monogastric digestive systems and had an opportunity to learn how to perform abdominal physical exams on some of the species from each group. This hands-on experience allows them to recognize normal and abnormal parameters to assist in generating differential diagnoses lists in the future. Similarly, the musculoskeletal course provides students the opportunity to learn about lameness in horses and hoof trimming in ruminants.

One of the more anticipated courses so far has been the “Cycle of Life.” Beyond learning about estrus cycles, gestation lengths, oogenesis and spermatogenesis, the students were introduced to examination of the uterus by rectal palpation (bovine), the prebreeding and cycle status exams (equine), and dystocia correction in ruminants and equine. By far the most excitement occurred during the lab which utilized the dystocia models.

Both the Food Animal Club and Equine Club (AAEP) have large student memberships and are regularly active at the college. Members of the Food Animal Club have, on multiple occasions, helped process cattle on local ranches and toured dairy facilities. A program has been established by the club for students to participate in regular pregnancy checks at a local dairy farm. Additionally, ten club members have been trained in bovine artificial insemination and there is a lot of interest in embryo transfer with students and staff working hard to get it organized. The AAEP has conducted wet labs throughout the year and several members participated in a burro castration through our partnership with the Bureau of Land Management. Other events, such as an equine lameness wet lab and an equine lymphatic drainage wet lab were held at the CVM facilities on the Campus Agriculture Center farm.

We’re grateful to have the Campus Agricultural Center as an extension of our program. Our large animal learning facility has opened the doors for our students to learn about large animal medicine and experience valuable hands-on training prior to their clinical year.

For more information please visit:

Dr. Gayle Leith and DVM students at a lab at the Campus Agricultural Center
Dr. Tony Martin teaching at the Bovine Education Extension Facility

The effects of sire, lactation number, and time of the year on late embryo mortality in dairy cattle

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Published on: December 20, 2021

C. Bailey, J. Gibbons, P. Melendez

Texas Tech University, School of Veterinary Medicine, Amarillo, TX 79106


In the dairy industry, there has been considerable drive to maximize birthing rates and profitability by using genetics from beef cattle in both lower performing and lower genetic quality cows. This has allowed cows that are of average quality or aged genetics to provide added value to the operation in the form of crossbred calves for the beef industry.

One measure of infertility in multiparous cows is late embryonic mortality. Although there is likely a higher percentage of embryonic loss during early pregnancy (prior to Day 30; [1]), late embryonic mortality (LEM; defined as pregnancy loss that occurs between 30 and 60 days of gestation) is also a contributor to low profitability. Other research has shown that roughly 12.8% of dairy cows will undergo LEM between 28-42 days post-breeding, averaging a 0.85% loss per day [1].  Some of the factors that cause LEM include genetics, infectious diseases, poor prophylactic management, sanitation, and season of the year.  However, genetic defects of the embryo may also account for up to 20% of early embryonic mortalities [2].

A common method of detecting pregnancy is by measuring Pregnancy Specific Protein B (PSPB) and plasma progesterone (P4) at specific times post insemination. An assay testing PSPB levels indicate a positive pregnancy if PSPB levels are a >10% above non-pregnant cow levels approximately 28 days post artificial insemination [3,4]. Elevated progesterone concentrations (>1 ng/ml) are also useful as a pregnancy detection aid, as they typically begin to taper off around 15 days post estrus in the non-pregnant cow but, are maintained in pregnant cows [5]. Both PSPB and P4 were evaluated and compared between groups in a subset of cows in this study.

The objective of this study was to compare the LEM of Holstein cows bred to Limousin bulls to Holstein cows bred to Holstein bulls. Optical density as a measure of PSPB and P4 concentrations were also evaluated from a blood sample collected at 30 days post breeding for comparison between a subset of 25 cows per group. Further, the LEM was evaluated based upon the time of year that the breeding occurred Summer (April 1 – September 30) and Non-Summer (October 1 – March 31).


The Limousin X Holstein and Holstein X Holstein breedings in this study were from a large dairy in the southeast US, which consisted of 12,847 Holstein cows. In this herd, 1,166 cows were dry with an average of 171 days open. The cows were milked 3 times a day with a rolling herd average of 14,600 kg of milk per year and were fed a total mixed ration based on corn silage, grass silage, and concentrates. The reproductive program consisted of a 60-day voluntary waiting period and timed artificial insemination using a variety of ovulation synchronization protocols. Cows were diagnosed for pregnancy status by trans-rectal ultrasound between 28 to 35 days post breeding. If the cow was diagnosed open, she was subjected to a resynchronization protocol. If the cow was diagnosed as pregnant, she was rechecked for pregnancy status between 50 to 57 days post breeding by rectal palpation. Blood was collected at random (n = 25 cows per group) at the time of ultrasound pregnancy diagnosis (28-35 days) and tested for PSPB levels expressed as optical densities and P4 concentrations measured by Radio-immuno Assay.


Normal LEM for this herd is approximately 12%. Overall, for all cows bred in the summer the LEM was 15.2 ± 0.6% while those bred in the non-summer had an LEM of 9.9 ± 0.3%, (P<0.0001). Overall, for all Holstein X Holstein embryos the LEM was 15.2 ± 0.6% while the LEM for all Limousin X Holstein embryos was 9.8 ± 0.3%, (P<0.0001).  Differences (P<0.05) in LEM between Holstein x Holstein and Limousin X Holstein were observed during the non-summer months (15.1 ± 0.8% versus 8.3 ± 0.3%, respectively) but not for the summer months (15.1 ± 0.9% and 15.3 ± 0.9%, respectively). summer = 15.23 +/- 0.6%, non-summer = 9.88 +/- 0.3%    P<0.0001

In Figure 1, lactations within breed combination that do not share a common superscript are different (P<0.05). Further, there was a trend (P=0.08) for a difference between Lactation 2 and Lactation 3 for Limousin X Holstein embryos in the non-summer months and there was a breed combination difference (P<0.05) for all lactations during the non-summer months but not for any lactations during the summer months.

Figure 1.  Late embryo mortality (mean ± SEM) percentage over multiple lactation in Holstein cows either bred to Holstein or Limousin bulls that were confirmed pregnant at approximately 30 days post timed artificial insemination either during the summer or non-summer months (see text for more details).

Effects of Season on LEM 

Cows bred in the summer months (Figure 1), regardless of mating, had a higher LEM compared to cows bred in the non-summer months.  A substantial difference in fertility was noted among cows carrying crossbred embryos especially during the non-summer months. Taken together, these data suggest that heat stress during the summer months combined with the stress of milk production, may affect the uterine environment specifically and these stressors cannot be overcome by altering the breed of the sire.  Alternatively, in the non-summer months, the crossbred embryo apparently adapts more readily to the stress of milk production alone than do the Holstein X Holstein embryos.

Protein Specific Protein B and Progesterone

Optical densities of PSPB and P4 concentrations were compared between groups that were diagnosed pregnant at Day 30. The results showed a PSPB optical density of 4.44 in the Holstein X Holstein group and a 3.25 in the Limousin X Holstein group with a pooled standard error of ± 0.27 and a P-Value of 0.023.  Progesterone concentrations were not different (P>0.05) between groups and were 8.66 ng/ml in the Holstein X Holstein group and 8.96 ng/ml in the Limousin X Holstein group with a pooled standard error of ± 0.57.


This field study demonstrated that breeding Holstein cows with Limousin semen reduced LEM by approximately 4% overall and there were seasonal and lactational differences in LEM. During the summer months, the breed combination had a lesser effect on LEM perhaps as all cows exhibited some form of heat stress; however, during the non-summer months, purebred Holstein embryos had a higher LEM than the Limousin X Holstein crossbred embryos, indicating inherent embryo loss dynamics due to factors other than genetics or lactation. These results indicated that breeding beef bulls to lower quality genetic Holstein cows decreased LEM regardless of time of year. However, the lower LEM was especially evident in early lactation cows bred during the non-summer months which likely contains cows that can still contribute genetically to the herd.  The exact components of the “protective mechanism” associated with producing crossbred embryos may be due to hybrid vigor, but has not been fully elucidated; however, it seems to be mostly present during the non-summer months underscoring the ever-present stress of milk production on the females.  The heat induced stress associated with the summer months historically [6] leads to an increase in LEM rates in Holstein embryos and was lactation dependent in both groups in this study. Progesterone concentrations for both groups were similar indicating that corpus luteum function was likely not related to LEM.  Lower optical density which is reflective of the concentration of PSPB was seen in Holstein cows bred to Limousin bulls versus Holstein bulls. More research may be necessary to determine if PSPB plays a role in embryo viability during early pregnancy or if elevated optical density of PSPB is reflective of embryos in distress [7].


1)  Wiltbank MC, Baez GM, Garcia-Guerra A, Toledo MZ, Monteiro PLJ, Melo LF, Ochoa JC, Santos JEP, and Sartori R. (2016). Pivotal periods for pregnancy loss during the first trimester of gestation in lactating dairy cows. Theriogenology, 86(1), 239–253. 

2)  Alfieri AA, Leme RA, Agnol AMD, and Alfieri AF.  (2019). Sanitary program to reduce embryonic mortality associated with infectious diseases in cattle.  Animal reproduction vol. 16,3 386-393. 22 Oct. 2019, doi:10.21451/1984-3143-AR2019-0073 

3)  Humblot F, Camous S, Martal J, Charlery J, Jeanguyot N, ThibierM, and Sasser RG. (1988).  Pregnancy-specific protein B, progesterone concentrations and embryonic mortality during early pregnancy in dairy cows. J Reprod Fertil. 1988 May;83(1):215-23. doi: 10.1530/jrf.0.0830215. PMID: 3397939.

4)  Middleton EL, and Pursley JR. (2019).  Short communication: Blood samples before and after embryonic attachment accurately determine non-pregnant lactating dairy cows at 24 d post-artificial insemination using a commercially available assay for pregnancy-specific protein B. J Dairy Sci. 2019 Aug;102(8):7570-7575. doi: 10.3168/jds.2018-15961. Epub2019 Jun 6. PMID: 31178191.

5)  Thirapatsukun T, KW Entwistle, and Gartner, RJW.  (1978). Plasma Progesterone Levels as an Early Pregnancy Test in Beef Cattle.  Theriogenology, Vol. 9, no. 4, pp. 323-332.

6)  Morton, JM, Tranter, WP, Mayer, DG, and Jonsson, NN. (2007). Effects of environmental heat on conception rates in lactating dairy cows: Critical periods of exposure. Journal of Dairy Science, 90(5), 2271–2278. 

7)  Thompson, IM, Tao, S, Branen, J, Ealy, AD, and Dahl, GE. (2013). Environmental regulation of pregnancy-specific protein B concentrations during late pregnancy in dairy cattle1. Journal of Animal Science, 91(1), 168–173. 

Dominant Follicle Removal Prior to Superovulation in Ewes

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Published on: December 20, 2021

 T. Mittleider a , C. Holcomba , D. Hobbs a, D. Davis c, L. Miller a , J. Gibbons a, b, d

a College of Veterinary Medicine, b DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN, 37752, c Laurel Highlands Animal Health, Somerset, PA, 15501, d Texas Tech University – School of Veterinary Medicine, Amarillo, TX, 79106

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The Effects of Melatonin on Ovine Estrus Cyclicity

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Published on: December 20, 2021

C. Holcomb b , D. Hobbs b, J. Gibbons a, b, d, D. Davis c

a College of Veterinary Medicine, b DeBusk College of Osteopathic Medicine, Lincoln Memorial University, Harrogate, TN, 37752, c Laurel Highlands Animal Health, Somerset, PA, 15501, d Texas Tech University – School of Veterinary Medicine, Amarillo, TX, 79106

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Welcome , today is Sunday, December 4, 2022