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Advances In Equine Science > Reproductive Technologies > Flashcards

Reproductive Technologies Flashcards

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1
Q

What do you need to check in mare and stallion before breeding

A
  • general Health (e.g teeth, eyes, faeces, injuries)
  • Reproductive history (used before, any issues)
  • Specific examination examination of reproductive organs (swabs) (std, damage)
  • semen evaluation
  • oestrus cycle
  • libido
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2
Q

What are acceptable fertility levels (rate/cycle and rate/season)

A

Preg rate/cycle = over 50% (abnormal = below 20%)

preg rate/season = over 80% (abnormal = below 60%

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3
Q

Specific examination of repro organs (3 examples)

A
  • swabs
  • samples
  • ultrasound
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4
Q

Sterile/infertile (def)

A

incapable of producting offspring

physical - removal of tract, physiological - prob developing oocyts/sperm

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5
Q

Sub-fertile (def)

A
  • reduced reproduction capacity
  • may get fertilisation
  • failure to conceive/carry pregnancy
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6
Q

Failure of fertilisation - why

A
  • timing of insemination wrong in relation to ovulation (early = sperm die off before ova arrive, late = ova at end of tube/uterus not implanted even if fertilised later as ova too progressed)
  • testicular/sperm factors/abnormalities (e.g motility)
  • ovarian factors/abnormalities
  • uterine disorders (failure of sperm to reach ovum
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7
Q

Fertilisation rate in mares

A

90-96%

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8
Q

Conception rate to first service in mares

A

50% (average of all breeds)

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9
Q

Conception rate to all services in mares

A

67-77% (TBs)

85% (quarter horses)

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10
Q

What are ATRs

A

= techniques to induce fertilisation and conception

Assisted Reproductive Technologies

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11
Q

Role of ARTs and why use them

A
  • stallion/mare factors prevent successful natural conception
  • reduced risk of disease and injury
  • convenience
  • greater choice of genetics (bred from different parts of world)
  • increase progeny quickly (can allow more than one offspring in a season)
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12
Q

Periods of development - embryonic period

A

= conception to organogenesis

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13
Q

Periods of development - foetal period

A

= organogenesis to end of gestation

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14
Q

Periods of development - natal period

A

= birth

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15
Q

Periods of development - neonatal

A

= early days to first 4 weeks of life

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16
Q

What is controlled reproduction

A
  • control of oestrus (e.g. bring forward so cycle in jan/feb, Gnrh injections)
  • control breeding (AI, embryo transfer
  • control preg test (blood test, scans)
  • control foaling (when due tests/alerts)
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17
Q

Artificial semination - why not use in TB racing

A
  • difficulty in establishing semen where comes from the stated stallion
  • overuse of top stallions = narrow gene pool
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18
Q

AI - collecting semen from stallions

A

either

  • mount mares in oestrus (ovariectomised and injected with hormones to mimic oestrus)
  • mount dummies (need training)
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19
Q

AI - semen collection

A
  • collected in AV (artificial vagina)
  • whole ejaculate collected
  • filtered through muslin cloth (remove gel)
  • HYGINE - sterile, cleaned thoroughly to prevent bacteria transfer to sample/other stallions
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20
Q

Three types of straws in AI

A
  • fresh (few hours, mare and stallion in same place)
  • chilled (can send in post 24-48hours)
  • frozen (overseas, difficult to do effectively
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21
Q

Types of semen extenders used

A
  • INRA 96 extender
  • E-Z mixi
  • skim milk extender

= give sperm energy and protect if chilled/frozen due to temperature
- can contain antibiotics if bac enter sample

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22
Q

What can increase conception rates (AI)

A

if seamen deposited

  • intrauterine (well into uterine body)
  • into same uterine horn as dominant follicle (left)
23
Q

Timing of insemination

A
  • 12 hour window in ovulation
  • inseminate 24-48 hours before uterus (allow sperm to travel through uterus and fallopian tubes, get to ampulla region to meet ova)
24
Q

What happens if you inseminate after ovulation and how to manage

A
  • higher EEL (early embryonic loss) rates
  • egg older by time fertilised
    12-24 hours after ovulation = reduce preg rate

scanning - every four hours during oestrus period
hormones - GnRH stimulate ovulation

25
Q

How many sperm needed for successful pregnancy

A

250-500 million progressively motile sperm

100 million high fertile stallions

26
Q

Low dose insemination

A
  • 1-20 million sperm
  • placed at tip of uterine horn or near oviductal papilla
  • use videoendoscope or transrectaly guided insemination catheter

Adv - need less sperm, use more times, one ejaculate can inseminate al ot of mares

  • stallion dead/have little available
  • use for sub-fertile stallions (increase chance fertilise)
27
Q

Is there an infection risk of AI

A

Yes - risk of infection and uterine fluid after insemination post-breeding endometritis)

  • use saline flush and infusion of antibiotics
  • oxytocin injection
28
Q

Embryo transfer - problems

A
  • cant be used for TB foals
  • no regimes available to super ovulate mares (produce multiple eggs at same time which all can be fertilised)
  • only collect 1 ebryo for implantation
29
Q

Method of embryo transplant - what’s needed

A
  • recipient mare (surrogate)

-

30
Q

Method of embryo transfer - recipient mare

A

= surrogate

  • clear breeding record
  • good temperament
  • 5-10 years
  • larger than donor
  • good heath (e.g. udder, monitor endometritis)
  • need to synchronise with donor (ovulate same time, 4-8 days after ovulation embryo inserted)
31
Q

What is endometritis

A

inflammation of the lining of the uterus

32
Q

Method of embryo transfer - collecting embryos (what to use)

A
  • collecting several embryos from one mare = use embryo recovery program
33
Q

Embryo recovery program

A
  • created to know when implant embryo
  • mate during dioestrus
  • 6-7 days after ovulation = embryo recovery
  • embryo enter day six and wanders in uterus and signals to body that preg
  • implants day 12
  • prostaglandin injection to break down corpus luteum lead to another wave of follicles
34
Q

When is uterus flushed

A

7-8 days after ovulation to collect embryo

  • catheter blown up
  • flush water through rectum and uterus
  • catch embryos
  • fluid filtered
35
Q

How embryos graded

A

in a lab 1-5 (1 and 2 best and only used) then washed

36
Q

What happens after grading embryos

A

embryo placed into recipient surgically or via cervix into uterine horn

37
Q

Conception rate for embryo transfer and storage

A

30-70%

  • stored up to 24 hours at 42 celcius
  • cooled to 4-5 celcius for 36 hours
  • freezing rarely works 20-40%
38
Q

Advantages of embryo transfer

A
  • reduces transport (cost and time)
  • expand rare genetic stock
  • allows mare to be ridden and compete
  • good for mares unable to hold pregnancy (physical problem) or young mares
  • multiple offspring a year
39
Q

When do you need to try other ARTs

A
  • mare cant provide embryo for transfer

- stallion semen not adequate to achieve good pregnancy rates from standard intrauterine insemination

40
Q

What do all ARTs need

A

collection of oocytes from donor mare - semi invasive and specialised technique
(except cloning)

41
Q

ARTs - Intracytoplasmic sperm injection (ICSI) process

A
  • used when low spermatozoa numbers
  • micromanipulator used to inject single sperm into oocyte from pre-ovulatory follicle
  • spermatozoon aspirated to tip of glass needle
  • oocyte held by suction
  • insert injection needle through zona pellucidia and injected into cytoplasm of oocyte
42
Q

ARTs Intracytoplasmic sperm injection (ICSI) after injection, what happens if successful and future work

A
  • oocyte either transferred immediately to oviduct of recipient mare or return to incubator and cultured for 24-48 hours
  • successfully fertilised = single cell oocyte cleave into 2 cells and cleave again etc
  • future = culture deveoping ICSI embryos for 5-7 days and transferred into uterus
43
Q

Advantages of ICSI

A
  • can use with low sperm count of few straws
  • can use when stallion no longer alive
  • produce multiple foals from single straw
  • allows conservation of rare breeds
  • skips requirement for sperm to penetrate zona pellicida (unlike IVF)
44
Q

Causes of sub and infertility

A
  • neoplasia
  • hormonal imbalance
  • age
  • condition (malnourished = use nutrients for survival)
  • injury (direct organ = inflamation, elsewhere pain leads to stress and immunosuppression = lower quality sperm)
  • miss management (no artificial light/heat and lack of nutrition)
  • first sperm collection for some time (dead sperm
45
Q

Advantages and disadvantages of AI

A
  • semen stored after stallion death
  • wider choice of genetics
    reduce risk of injury/infection
  • reduce traveling
  • safer for handlers
  • one ejaculate inseminate many mares
  • stallion keeps working
  • still need to transport samples (cost)
  • expensive procedure
  • not accepted by TB racing industry (narrow gene pool)
46
Q

Effect of deslorelin in mares for inducing ovulation in mares during transition period vs ovulatory season

A

(Gomes et al 2014)

  • synthetic hormone which is administed into the muscule or subcutaneously
  • equivalent to GnRH which results in release of FSH and LH to induce ovulation
  • transitional period = prolonged oestrus with no ovulation
  • during transitional period Control (saline) ovulation induction = 4.34% but deslorelin = 78.6% (ovulatory control = 16.4, deslorelin = 68.8)
47
Q

Welfare issues of AI

A
  • depleting strength for stallion normal reproductive behaviours = low libido compared to stallions that do natural service and exposed to mares secretions
  • lack of evidence that AI isnt painful/stressful to mares
48
Q

Welfare issues of embryo transfer

A
  • increased incvasie examination and phrarmalogical manipulation compared to ai
  • embryo flishing may be painfull/stressful although cervix dilates easier compared to other species
  • more than one recipient mare prepared per donor to increase chance of synchronisation = no. invasive rectal ultrasounds examinations higher than AI
  • pharmaogical manipulation of hormone injections
49
Q

Welfare issues with oocyte retrieval and transfer

A
  • transvaginal ultrasound-guided follicular aspiration
  • a study in cattle (Petyim 2007) associated with increased heart rate, cortisol levels and development lesions but might be due to epidural anaesthesia
  • another case study study (Vanderwall and Woods) severe internal haemorage due to TUGFA. mare one of 132 mares with 388 TVA procedures that did not arrise in complications so risk low but can be fatal
  • insertion of needle through vaginal wall associated with pain and increases risk of pathogen transmission and vaginal rupture
  • fetal oversize linked to culture conditions of oocytes and embryos = trouble parturition
50
Q

Welfare issues of cloning

A
  • increase risk of foal having abnormalities at birth which leads to increased need for neonatal intensive care
  • Poor sucess rate = Galli et al 2003 produced 3 foals out of more than 100 cloned embryos
51
Q

What is nuclear transfer

A
  • remove DNA from oocyte and inject nucleus which contains DNA to be cloned
  • zona pellucida free found more oocytes fused to various somatic cells such as granulosa cells and cleavage (divide) rate higher than oocytes with zona pellucida
52
Q

What is invitro fertilization

A
  • egg fertilised by sperm outside body in lab
53
Q

What is gamete intrafallopian transfer

A
  • multiple eggs collected from ovaries
  • mixed with sperm
  • gametes injected into fallopian tubes
  • embryo development in FT

Advances In Equine Science (22 decks)

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