Equine - Assisted Reproductive Techniques Flashcards
What is the most well known and used assisted reproductive technique?
Artifical insemination
What type of semen is used in AI?
performed with fresh, shipped cooled, or frozen semen
AI is a tool of _______. How/Why?
Convenience
You can breed to mares all over the US, Canada, and even parts of Europe
Prevent injury to mare, stallion, and handlers
Minimize disease transmission
Eliminates need for mare transit to stallion location
Where is semen depopsited in AI?
Within the uterus
What is the minimum requirement for progressively motile sperm in fresh or shipped cooled semen?
500,000,000 progressively motile sperm
What type of semen is used in deep horn insemination?
frozen
What is the viability of frozen semen as compared to fresh or chilled semen?
decreased viability and quality
When would you use deep horn insemination in regards to the stallion (semen type/history)?
The stallion is subfertile - poor numbers, motility, or percent, history of decreased or poor pregnancy rate
True or False: Deep Horn insemination is good to use in a subfertile mare.
TRUE
What is the minimum requirement for progressively motile sperm in frozen semen?
400,000,000 progressively motile sperm
Equine embryo transfer is often ____ by many owners.
elected
Why might an owner elect to do embryo transfer?
They will get multiple offspring per year
Allows the mare to continue training and/or competing
Obtain offspring from young donor mares who have entered puberty
It can be used in mares who have reproductive difficulty in maintaining a pregnancy either due to cervical incompetence or inadequate uternie environment
Mares who are unable to carry a foal to term due to non-reproductive reasons (pelvic trauma, musculoskeletal abnormalities etc.)
Or in mares who have experienced difficult foaling on previous pregnancies
What are some requirements for embryo transfer due to breed restrictions?
Many require verification of parentage through genetic testing
Registration of number of foals/year
Many registrations must be contacted prior to transfer
How long must a donor mare be able to maintain a pregnancy in order to be a viable candidate for embryo transfer?
the first 6 to 8 days
What is the ideal semen type for a donor mare to be bred with?
fresh or shipped cooled semen
When is a donor mare flushed?
between days 6.5 and 8 post ovulation
What is the recommended age for an ET recipient?
young - 3-10 years of age
What requirements do the ET recipients need to have in order to be applicable for ET?
reproductively sound - grade I to IIa endometrial biopsy and a negative culture/cytology
Systemically and musculoskeletally sound
What is one of the biggest keys to success of ET?
recipient mares must be matched to the donor mare - cyclicity
When must a recipient mare ovulate in relation to when the donor mare ovulates in order to be successful?
Must ovulate day prior to, day of, or up to three days after donor
What hormones can be used to aid in synchronization of the recipient mare?
prostaglandins and hCG/GnRH
Can synchronization be done in anestral or ovariectomized mares?
yes
What is the process of embryo flush?
Insert a Ballona catheter through the mares cervix, inflate a balloon, and lodge it against the internal cervical os. Then attach y-tubing to the end of the catheter to add flush media into the uterus and dislodge the embryo and efflux the embryo out of the y tubing into a filter
With fresh or cooled shipped semen when do you want to flush the mare?
7-8 days
With frozen semen when do you want to flush the mare?
8 days
With a cryopreserved embryo when do you want to flush the mare?
6.5 days
Once embryos are received, what is the next step?
to grade based on age and quality
What will indicate an embryo is 6 days old?
it will be a morula
What will indicate an embryo is 6-7 days old?
it will be a blastocyst
What will indicate an embryo is 7.5-8 days old?
it will be an expanded blastocyst
Grade _ indicates a good quality embryo, grade _ indicates a bad quality embryo.
1, 4
What is the average embryo recovery rate? In young fertile mares?
50-70%, 70-75%
What is the success transfer rate for grade I or II embryos?
50-70%
What is the success transfer rate for grade III embryos?
30-50%
Overall, what is the percentage of obtaining a successful pregnancy per cycle?
25-50% - this is the bolded important point
What is oocyte aspiration
obtaining oocytes from the follicle of the mare at a flank or transvaginal approach and then using subsequent methods to abtain successful fertilization
When might you choose to do oocyte aspiration?
In performance mares that you do not want to take the time out of work/competition
Difficult mares - frequently diagnosed not pregnant or who upon embryo flushing, no embryos are obtained
Mares with chronic inflammation or uterine infections, oviductal or uterine adhesions, or mares who may frequently experience ovulation
What is the most common method of oocyte aspiration?
transvaginal oocyte aspiration - both ovaries are typically done and large and small follicles are aspirated
What are the common methods of transfering aspirated oocytes into recipients?
Oocyte transfer, gamete intrafallopian transfer (GIFT), and Intracytoplasmic sperm injection
How is oocyte transfer done?
surgical transfer of oocyte into the oviduct of the recipient mare
Oocyte transfer is typically done when recipient mares are bred with _______ _____ prior to and after transfer and have _______ ______ of any follicles present.
fresh semen, transvaginal aspiration
How is gamete intrafallopian transfer (GIFT) done?
Surgical transfer of collected oocyte and small number of spermatozoa into the oviduct of a recipient mare
When may GIFT be considered?
when utilizing fresh semen - more successful (like a lot higher)
What is the most routinely done oocyte fertilization technique following aspiration?
Intracytoplasmic sperm injection
What is Intracytoplasmic sperm injection (ICSI)?
spermatozoa are directly injected into a single oocyte, the oocyte is cultured and monitored for division, and then the embryo is transferred or cryopreserved until desired
What is the average amount of tranferrable embryo/ attempt of the transvaginal aspiration and ICSI combination?
1 embryo
What is vitrification?
a series of adding cryoprotectants and cryopreservation quickly to cryopreserve it
When is embryo cryopreservation the most successful?
with day 6 to 6.5 of embryos
What size embryo is associated with more success in embryo cryopresentation?
biopsy of larger embryos
What is the success rate (general not number) of embryo cryopreservation as compared to fresh transfer?
success is reduced
How many cells are used for genetic testing on an embryo biopsy?
5-10 cells of a 6 to 7 day embryo
Since it takes 36 to 48 hours to get embryo biopsy results, what should you do with the embryo?
cryopreserve it until you get the results
What can you test for genetically in an embryo biopsy?
HYPP, HERDA, GBED, MH, PSSM, Lethal white overo, CA, Lavender foal syndrome, SCID, gender determination, coat color determination
If a mare passes away or is euthanized, can you still recover oocytes?
Yes, the whole ovaries or oocytes can be collected directly from the ovary and are shipped to a facility capable of performing ICSI and embryo maturation or OT/GIFT
If you choose to ship the entire ovary, how quickly do they need to arrive at the recovery center?
ideally within 4-6 hours
If you choose to harvest some oocytes how quickly do they need to arrive at the recovery center?
shipped via next-day or same-day shipment
What is epididymal semen collection?
The collection of spermatozoa via flushing of the tail of the epididymis of stallions following euthanasia, unexpected death, or after castration
What can be done to semen collected from epididymal semen collection?
It can be frozen and stored for further use, or used immediatley
What is the average success rate of epididymal semen collection?
The average is 10-15 doses of semen - depends on comorbidities
How is cloning done?
Somatic cells (male or female) are collected from the donor animal and transferred into a enucleated oocyte. The subsequent embryo is transferred into a recipient mare. Note: it is very expensive $85,000-150,000
<p>Can cloning be done with cells from a gelding (castrated horse)?</p>
<p>yes</p>
