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Vet Med Year 1 > Advanced Reproductive Techniques > Flashcards

Advanced Reproductive Techniques Flashcards

1
Q

Management of Reproduction: Benefits

A
  • 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
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2
Q

What methods can we use to manage reproduction in farm species?

A 
Nutrition
Day length
Temperature
Socio-sexual signals
Pheromones
Hormones
Genetic selection for productivity Assisted reproductive technologies (ARTs)
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3
Q

Assisted Reproductive Technologies

A 
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 semen
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4
Q

Semen Storage

A
  • Semen storage has numerous stages:
  • Semen collection
  • Semen assessment
  • Sperm processing (liquid storage or cryopreservation)
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5
Q

Reasons for Semen Collection

A

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

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6
Q

Semen Assessment

• What can we analyse?

A
  • 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
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7
Q

Sperm Cryopreservation Protocol

A

30°C water bath ➡️ Cool to 5°C over 2 hours➡️ Freeze➡️ Pellets or straws

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8
Q

Semen Storage is Species Dependent, describe the storage of

Sheep (Ram)

A

Cryopreservation possible.

Post-thaw motility rates of approx. 50%

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9
Q

Semen Storage is Species Dependent, describe the storage of

Cow (bull)

A

Cryopreservation possible. Post-thaw motility rates of 50-60%

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10
Q

Semen Storage is Species Dependent, describe the storage of

Pig (boar)

A

Cryopreservation low success rates

Boar spermatozoa stored chilled (15C) up to 5 days

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11
Q

Semen Storage is Species Dependent, describe the storage of

Horse (stallion)

A

Cryopreservation possible. Post-thaw motility rates of up to 70%

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12
Q

Semen Storage is Species Dependent, describe the storage of

Turkey (tom)

A

Cryopreservation unsuccessful

Tom spermatozoa stored chilled (5C) up to 2 days

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13
Q

Advantages of Cryopreservation and Semen Storage

A
  • 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
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14
Q

Sex-Sorted Semen

A 
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)
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15
Q

Sex-Sorted Semen in the Dairy Industry

A
  • 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)

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16
Q

The advantages of artificial insemination

A

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

17
Q

Disadvantages of AI

A
  • 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.
18
Q

Artificial Insemination

A

Method is dependent on two main factors: Species and semen type Success is dependent on: site of deposition, sperm dose and timing of AI

19
Q

Species Differences: Site of deposition Sheep

A

Fresh semen: Vaginal/cervical
Chilled semen: Laparoscopic (uncommon)
Frozen-thawed semen: Laparoscopic IU
FT semen low dose: Laparoscopic IU

20
Q

Species Differences: Site of deposition Cow

A

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)

21
Q

Species Differences: Site of deposition Horse

A

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)

22
Q

Species Differences: Site of deposition Pig

A

Fresh semen: Cervical
Chilled semen: Cervical (deep)
Frozen-thawed semen: IU/deep IU (uncommon)
FT semen low dose :Deep IU (uncommon)

23
Q

Species Differences: Site of deposition Turkey

A

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)

24
Q

Artificial Insemination in Livestock systems

• Dairy

A
  • 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
25
Q

Artificial Insemination in Livestock systems • Pigs

A
  • With chilled (15degC) semen
  • No sire maintenance
  • Availability of genetics (JSR and PIC) • Very reliable. 90% conception rates
26
Q

Artificial Insemination in Livestock systems Poultry (Turkey)

A

• A necessity. Tom can weight in excess 33Kg, hen 9Kg at lay. Unable to
mount and mate
• Reduce sire maintenance
• Inseminate hen every 7-10 days
• 100% fertilised eggs
• No sex-sorting despite advantages (i.e. females for breeding, males for meat) as sex not determined by X/Y chromosomes in avians.

27
Q

Artificial Insemination in Livestock Systems Sheep

A
  • Lap AI utilised only by pedigree flocks.
  • We can not penetrate the cervix and FT semen can not transit the cervix = low conception rates
  • Natural breeding
28
Q

Embryo Transfer

A

The transfer of embryos to a recipient female
Embryos may be produced in vivo (in donor female) or in vitro (IVP)
Multiple Ovulation Embryo Transfer (MOET) (in vivo) Ovum pick up in vitro production (OPU-IVP)

29
Q

Multiple Ovulation Embryo Transfer (MOET) (in vivo)

A

Donor female of high genetic merit administered hormones to induce superovulation
Donor female inseminated with semen from male of high genetic merit
Multiple embryos recovered and transferred to recipient females of lower genetic merit

30
Q

Ovum pick up in vitro production (OPU-IVP)

A

Donor female of high genetic merit Natural collection or after superovulation
Oocytes collected via a needle inserted through the vagina (with ultrasound)
Oocytes fertilised with semen in the laboratory
IVP embryos transferred to recipients on day 7

31
Q

Advantages of MOET/OPU-IVP

A
  • Rapid dissemination of genetics = increased rate of genetic gain • 30% Increase in cattle from one MOET cycle
  • Multiple offspring from one female in one year as opposed to 1 or 2 per year • Moet 20-30/yr
  • OPU 80-100/yr
  • Reduced spread of disease
  • Can obtain embryos from females that can’t carry/rear offspring • Long-term storage of cryopreserved embryos
  • Pregnancy rates of 65-75% in cows (highest in heifers) in MOET • Pregnancy rates of 40-60% in cows with OPU-IVP
32
Q

Disadvantages of MOET/OPU-IVP

A
  • Size of gene pool reduced
  • Costly
  • £560/ewe for superovulation, AI and embryo recovery
  • £430-560/ewe for superovulation, embryo recovery and transfer
  • Variability in superovulatory response or success of OPU in individuals
  • Asynchrony of oestrous and ovulation between donor and recipient ewes • Fertilisation failure in females with extremely high ovulation rate
  • Requires technical ability

Vet Med Year 1 (131 decks)

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