Advanced Breeding Techniques Flashcards
Foetal Sexing - Equine, Bovine
~60d
Genital tubercles on US
Female Fecundity
- Donor animals can’t support pregnancy or desired number of pregnancies
- Superovulation - increase number of ova released/ cycle
- Embryo collection and transfer - gestation independent of donor
- IVF - conception independent of donor
- Oocyte maturation - oocyte maturation independent of donor
- Oocyte transfer
- Intracytoplasmic sperm injection - horses - overcome male infertility
- Cloning
- Genetic Salvage - unexpected death
- Gene therapy/ manipulation
Embyro Collection and Transfer
- MOET = Multiple Ovulation and Embryo Transfer
Dairy Cattle
Variable response
1/3rd = no transferable embryos
1/3rd = 1/2
1/3rd = 5-12
Superovulate with FSH
Embyro Collection and Transfer - MOET
- Superovulation
Day 0 = reference heat
Day 9-11 = FSH
Day 12 = PG + FSH
Day 13-14 = Heat/ AI
Day 15 = AI
Day 21 = embryo collection/ flushing
Decreasing doses of FSH 2x/d
Superovulatory heat 36-148hrs after PG injection
AI x2 12-24hrs after heat
Flushing 7d after heat
Embyro Collection and Transfer - MOET
- Embryo Collection/ Flushing
Insert catheter into uterus - 1x in each horn
Inflate balloon
Insert liquid into uterine horn multiple times
Embyro Collection
Ewe, hind, bitch
Laparotomy/ laparoscopy
- Oviductal flush - 1 way
Embyro Collection and Transfer
Storage
Nitrous oxide
Embryo Transfer - Bovine
Epidural anaesthesia
ID CL - implant on same (ipsilateral) horn
Trans-cervical - ideally deposit embryo in anterior 1/3rd of uterine horn
Pregnancy rates (maiden heifers) 60-70%
Embryo Collection and Transfer
Equine
Benefits vs constraints
Day 6-7 post AI
Constraint:
- Can only do one at a time as ovulation occurs in ovulation fossa so there isnt enough room for multiple eggs at once
Benefits:
- Freedom from gestational restrictions
- Non-surgical
- Pregnancy rate >50%
Ovum Pick UP (OPU):
Equine
Insert into vagina
Do rectal w US
Aim in into vaginal canal and aspirate
Ovum Pick UP
Equine - Pre-ovulatory follicle aspiration
Recovery rate = 76%
- follicle is already well developed
Options:
- Transfer to recipient mare (OT)
- Intracytoplasmic sperm injection (ICSI)
- Donor and recipient are synched
- OPU
- Get rid of recipients oocyte
- AI recipient
- Transfer surgery
- Pregnancy check 14d
Ovum Transfer - Equine
Adv vs Disadv
Adv:
- ~simple tech
- limited requirement for oocyte handling
Disadv:
- fresh transfer - needs synchrod recipient, recipient herd
- surgery
Pregnancy rates >70%
Ovum Pick Up
Immature Ova - Bovine/ Equine
Superovulation w FSH
Transvaginal US guided Cumulus Oocyte Complex collection
Oocyte maturation
IVF/ICSI
Transfer to synched recipients +/- freeze embryos
Savage procedure - PM
IVF - Steps
- Donor Female
- OPU
- Maturation - 22-24hrs
- Kept in low O2 levels = expanded cumulus
- IVF
- 44hr culture = embryos 8-cell
- 7 days = morulas/ blastocysts
- Recipient females
IVF - Bovine
Adv vs Disadv
20-25% oocytes collected by OPU dev into transferable embryos
Pregnancy rates ~40%
Adv:
- can be done at any stage of cycle
- can be collected weekly
- Very young heifers and pregnant animals
- Large quantities of oocytes collected per session (~40 oocytes)
- Reduced semen costs
Disadv:
- Dont freeze well
- higher rate of loss and abnormal calves
Intracytoplasmic Sperm Injection (ICSI)
- Equine
Removes need for sperm to penetrate zona pellucida
Human oligospermia
Max foals: sperm
Genetic savage
OPU - recovery rate 70%
IVC - embryos cultured for 7-10ds
- development kinetics differ from in vivo
Intracytoplasmic Sperm Injection (ICSI)
- Equine
- Steps
- Oocyte pick up
- In vitro maturation
- Intracytoplasmic sperm injection
- In vitro culture
- Embryo transfer, cryopreservation
Epididymal Sperm Collection
Savage procedure
Collection - post castration/ PM
Transport - <18hrs, 5°c before collection
In wild species w limited populations
Cloning - Nuclear
Nuclear transfer - Somatic Cell nuclear transfer
Cloning - Blastomere
4/8 stage
Max 5 viable offspring - totipotent
Cloning - Embryo splitting
Cut embryo in half
Each half rounds off to repoduce 2 viable off spring
