Assisted Reproductive Techniques

Question 1

Why is embryo transfer used?

Answer 1

• competition mares
• mares unable to carry their pregnancy
• increase number of foals mare can produce
• use in preservation of rare breeds

Question 2

How is the embryo mare prepared?

Answer 2

1) Induce oestrus: administer PGF2a (day 5-14 of oestrous cycle)
2) Induce ovulation 6 days later: administer hCG
3) Breed (natural cover or AI) 24-48 hours later
4) Recover embryo day 8 post ovulation

Question 3

What is the procedure of extracting the embryo?

Answer 3

• Restrain and clean mare
• Three way Foley catheter
  introduced through cervix
• Cuff inflated through inlet
  tube
• In-line filter connected
• Dulbecco’s PBS introduced
• Medium collected back
  through in-line filter

Question 4

How are embryos assessed?

Answer 4

• morphology is matched with age
• scored as a 1-5 ( 1= excellent, 5= dead)

Question 5

How are embryos stored?

Answer 5

• use immediately
• store at 25-28 degrees for 24 hours for transport
• Chilled storage = cooled to 4-5 (24-48 hour storage)

Question 6

What is the method of cryopresevation?

Answer 6

• freezing embryos
• slow cooling to -19
• poor sucsess
• ice crystal formation must be avioded

Question 7

What is the method of vitrification?

Answer 7

• embryo formation
  -Ultra rapid cooling to prevent ice crystal formation

Question 8

How does embryo transfer occur?

Answer 8

• similar procedure to AI insemination

Question 9

What are the success rates of using Embryo transfer?

Answer 9

• 60-77% using fresh semen
  -reduced on mare age and endometritis history

Question 10

Why is oocyte transfer used?

Answer 10

• mares that cant produce an embryo
• chronic endometritis
• malfunction of the oviduct
• idiopathic infertility
• ICSI lab unavalible

Question 11

What is the method of oocyte transfer?

Answer 11

• collect oocyte donor from ovary
• inseminate recipient
• transfer oocyte to recipient oviduct

Question 12

How do to ensure synchronisation for oocyte transfer?

Answer 12

Follicle sizes in both donor and recipient
must be receptive hCG
- Administer hCG to both donor and
recipient
- 24-35 hrs later aspirate dominant follicle of
both mares
(as oocyte recovery method)
- Inseminate recipient mare with semen of
stallion of choice
(AI or natural cover)
- Transfer oocyte 36 – 40 hours after hCG
administered
(surgical flank incision)

Question 13

What are the success rates of oocyte transfer?

Answer 13

• recovery = 70%
• pregnancy rate after transfer = 30-50%

Question 14

What is Gamete intra-fallopian tube transfer (gift)?

Answer 14

Transfer both oocyte and sperm to a recipient

Question 15

Why is GIFT used?

Answer 15

• where oocyte transfer is necessary an there is poor quality sperm available
• avoids persistent mating-induced endometritis in recipient
• best with fresh non extended seamen

Question 16

What is the method for using GIFT?

Answer 16

• syncronise mares (oocyte transfer)
• oocyte recovery
• collect semen and select sperm
• transfer oocyte and sperm in same pipette to recipient

Question 17

What is the sucess rate for GIFT?

Answer 17

82% with fresh sperm

Question 18

Why is cloning used?

Answer 18

• enable geldings to produce offspring
• enable endangers/ extinct animals to be conserved
• mass production of desirable horses
• enables dead animal to produce offspring

Question 19

What is the method of cloning?

Answer 19

• remove nucleus from oocyte
• inject nucleus from somatic cell
• electric shock stimulation
• cell devision

Question 20

What are the ethical considerations for cloning?

Answer 20

• epigenic means offspring are not alwas identical in phenotype
• foetal and live born offspring may have health issues
• expensive

Question 21

What is the success rate for clonining?

Answer 21

poor