Advanced Reproductive Techniques Flashcards
Management of Reproduction: Benefits
- Maximise productivity
- Improvepregnancyandfertilityrates
- Aid management
- Synchronised/timed breeding and births
- Breed for sex
- Identify unproductive/infertile animals
- Improve genetics
- Usebestsiresanddams
- Increaserateofgeneticgain
- Maximise health and welfare • Diseasecontrol
- Reduceriskofinjury
- Improvemanagementofdamduringgestation • Reduceunwantedoffspring
- Maximise profit
What methods can we use to manage reproduction in farm species?
Nutrition Day length Temperature Socio-sexual signals Pheromones Hormones Genetic selection for productivity Assisted reproductive technologies (ARTs)
Assisted Reproductive Technologies
Intracytoplasmic sperm injection (ICSI)
Artificial insemination
Transgenesis
Cloning
In vitro embryo production (IVP)
Oestrus synchronisation Semen Storage
In vitro fertilisation (IVF)
Embryo transfer
Sex-sorted semenSemen Storage
- Semen storage has numerous stages:
- Semen collection
- Semen assessment
- Sperm processing (liquid storage or cryopreservation)
Reasons for Semen Collection
Artificial Insemination: Rapid rate of genetic gain, Incapacitated males, Control of disease
ICSI
MOET
Cryopreserve (freeze) sperm:Patients/animals with impaired fertility, Storage and transport of genetics, Conservation / endangered animals
Semen Assessment
• What can we analyse?
- Motility: wave motion, sperm motility
- Concentration: colour, consistency, cell number
- Morphology (what does the sperm look like)
- Other more advanced techniques available i.e. Computer Assisted Sperm Analysis (CASA), acrosome integrity, DNA integrity
Sperm Cryopreservation Protocol
30°C water bath ➡️ Cool to 5°C over 2 hours➡️ Freeze➡️ Pellets or straws
Semen Storage is Species Dependent, describe the storage of
Sheep (Ram)
Cryopreservation possible.
Post-thaw motility rates of approx. 50%
Semen Storage is Species Dependent, describe the storage of
Cow (bull)
Cryopreservation possible. Post-thaw motility rates of 50-60%
Semen Storage is Species Dependent, describe the storage of
Pig (boar)
Cryopreservation low success rates
Boar spermatozoa stored chilled (15C) up to 5 days
Semen Storage is Species Dependent, describe the storage of
Horse (stallion)
Cryopreservation possible. Post-thaw motility rates of up to 70%
Semen Storage is Species Dependent, describe the storage of
Turkey (tom)
Cryopreservation unsuccessful
Tom spermatozoa stored chilled (5C) up to 2 days
Advantages of Cryopreservation and Semen Storage
- Long-term storage of spermatozoa/genetics
- Use of incapacitated males
- Ease of transport (if used with AI)
- Controls spread of disease (no direct contact on mating)
- Reduced sire maintenance
Sex-Sorted Semen
Separating male (Y) and female (X) sperm • Female (X) sperm have more 3.8% DNA than male (Y) sperm • Sperm stained with DNA-fluorescent dye • Level of fluorescence detected by flow cytometer (MoFlo) • Level measured against set parameters • Sperm deflected to X, Y or waste • 98% accuracy (often used at 90-95%) • Low sperm numbers (high waste)
Sex-Sorted Semen in the Dairy Industry
- Use with artificial insemination to breed offspring of the desired sex
- Replacement heifers
- Use x-bearing sperm
- Guarantee female offspring (milk producers) • Increased rate of genetic gain (up to 15%)
- Offspring for beef production
- Use Y-bearing sperm
- Faster growing calves – increased productivity, higher meat prices
• Heifers:
• First calf
Sex-Sorted Semen in the Dairy Industry
• Higher calving rates than multiparious cows (55-60% vs 35-40%) (Lonergan et al 2016)
• Smaller uterus (Baez et al 2016)
• Inseminate with X-bearing sperm
• Female calf 2kg lighter than male (George and Seidel 2013)
• Dystocia (difficulty birthing) conventional semen 6%, SS-semen 4.3% (Norman et al 2010)
The advantages of artificial insemination
Increased Rate of genetic gain 50/yr vs. 1000/2-3 wk
(sheep)
Out-of-season breeding (sheep) Use in season semen
Ease of transport
Increased Breeding efficiency Remove sub-fertile males, inseminate all females
↓ sire maintenance
Synchronised breeding
Use of incapacitated males
Prevention and control of disease
Disadvantages of AI
- Inbreeding
- More prevalent in a small flock or herd.
- Care must be made to ensure selection intensity is not too high. • Can have opposite effect (more sires available).
- Reduced fertility
- Pregnancy rates can be less than with natural mating.
- Can be caused by incorrect handling of semen or unsuccessful oestrus synchronisation.
- Cost
- Technician, drugs, hormones, semen.
- Cost per insemination relatively low, cost of labour, drugs and hormones is greatest.
Artificial Insemination
Method is dependent on two main factors: Species and semen type Success is dependent on: site of deposition, sperm dose and timing of AI
Species Differences: Site of deposition Sheep
Fresh semen: Vaginal/cervical
Chilled semen: Laparoscopic (uncommon)
Frozen-thawed semen: Laparoscopic IU
FT semen low dose: Laparoscopic IU
Species Differences: Site of deposition Cow
Fresh semen: Transcervical intrauterine (TC IU)
Chilled semen: TC IU
Frozen-thawed semen: IU/ deep IU (uterine horn)
FT semen low dose: Deep IU (uterine horn)
Species Differences: Site of deposition Horse
Fresh semen: Transcervical intrauterine (TC IU)
Chilled semen: TC IU
Frozen-thawed semen: IU/ deep IU (uterine horn)
FT semen low dose: Deep IU (uterine horn)
Species Differences: Site of deposition Pig
Fresh semen: Cervical
Chilled semen: Cervical (deep)
Frozen-thawed semen: IU/deep IU (uncommon)
FT semen low dose :Deep IU (uncommon)
Species Differences: Site of deposition Turkey
Fresh semen: Vaginal
Chilled semen: Vaginal
Frozen-thawed semen: Not performed (sperm can not be cryopreserved)
FT semen low dose: Not performed (sperm can not be cryopreserved)
Artificial Insemination in Livestock systems
• Dairy
- Predominantly with Sexed FT semen in heifers and non-sexed FT semen in cows
- No sire maintenance
- Increase rate of genetic gain- More inseminations per day than a bull can serve naturally • 40% conception rates
- Sex-selection
