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541 (sex class) > ART > Flashcards

ART Flashcards

1
Q

describe the sex-sorted sperm process

A

based on different sizes of X and Y chromosomes X is bigger

  • fluorescent dye binds to DNA
  • laser detects dye
    • or - pulse sorts the cells into X, Y, or waste (~75% waste)
  • ~90% purity
  • ~3h to sort 1 ejaculate
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2
Q

describe how you use AI in cattle

A

intra uterine, horn
frozen most common

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3
Q

describe how you use AI in pigs

A

trans-cervical
fresh or cooled

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4
Q

describe how you use AI in small ruminants

A

vaginal (fresh), cervical (fresh), uterine (laparoscopy, frozen)

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5
Q

what are the pros of AI

A
  • widespread use of superior males and quicker genetic gain
  • use of genetic material across geographic distances
  • disease control
  • reduced possibility for injury (valuable sires)
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6
Q

what are the cons of AI

A
  • potential to disseminate non-desirable traits (milk prod vs fertility)
  • requires intensive management of females (ovarian mgmt)
  • potential to narrow genetic variation in a population using few sires (inbreeding)
  • AI is not accepted by all breed registries
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7
Q

what are the pros to using sex sorted sperm?

A
  • more sustainable prod systems
  • breed genetically superior animals for replacement
  • decrease calf wastage (ex. dairy bull calves)
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8
Q

what are the limitations to using sex sorted sperm?

A
  • some damage to cells so shortened capacitation (75% sperm discarded)
  • adjustment to AI protocols = delayed AI by 6-18h after start of standing heat
  • reduced conception rate by 15-20%
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9
Q

describe how you use AI in horses

A
  • 35mm dominant follicle
  • can do normal dose sperm or low dose
  • normal dose –> 20-40mL into uterine body –> but if inflammatory rxn or fluid accumulation, then no gx)
  • low dose –> 1mL deep horn insemination or hysteroscopic insemination

both procedures have acceptable preg rates for good fertility stallions and mares - don’t use low dose for sub-fertile or infertile studs and mares with repro problems

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10
Q

describe how you use AI in dogs

A
  • vaginal (fresh and cooled)
  • laparascopy (frozen)
  • fertility: lap > vag
  • transcervical (endoscopic)
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11
Q

what is most important when using AI in dogs?

A

knowledge of dog estrus cycle (LH surge, cytology, P4 concentrations, vaginoscopy)

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12
Q

which species have the highest ET?

A

cattle

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13
Q

what are the 2 types of embryo transfer?

A

in vivo derived (IVD) and in vitro produced (IVP)

IVD: fertilization happens in the female
IVP: egg harvested and fertilized outside of female

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14
Q

why do we use ET?

A
  • rapid genetic advance and reduction of generational interval
  • germoplasm and propagation of endangered species
  • bypass maternal blocks for early embryo development (an ovulation, repeat breeders, early embryo mortality)
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15
Q

what are the problems with ET?

A
  • increase ovarian manipulation can reduce quality and fertility
  • modulation of early embryo development - long term epigenetic changes
  • pregnant, but fetal probs (stillbirth, abortion)
  • recipient synchronization required
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16
Q

how do the pregnancy rates of ET compare with AI?

A

% preg rate lower or comparable to AI

17
Q

briefly describe IVD - MOET.

A

in vivo derived - multiple ovulation and embryo transfer

based on FSH treatment to “rescue” follicles destine to atresia
- increase recruitment window = FSH
- FSH days 8-12 of cycle + CIDR –> AI heat –> embryo collected day 7 (blastocyst)

on day 7, cow flushed
- one horn flushed at a time, each horn flushed 3x, warm water
- flush as frequent as every 4 weeks

18
Q

how many embryos does it take for ET to have a good and excellent response in cattle?

A

good: 6-9 embryos
excellent: 10-20 embryos

long story short, the more embryos, the more success

19
Q

ET is useful in cattle with what factors?

A

repeat breeders
cows under heat stress

20
Q

when using ET, the donor should be synchronized to what days?

A

day 6-7

21
Q

ET fertility fresh vs frozen

A

fresh > frozen

22
Q

usually code ____ & ____ transferred fresh and possible frozen with ET

A

1 & 2

23
Q

success of ET depends on what factors?

A
  • donor selection (fertile, good BCS, repro issues)
  • fertility of semen
  • superovulatory response
  • proper timing of AI
  • embryo recovery and handling
  • recipient selection (cycling, no repro issues, healthy, good BCS, 2+ parity)
24
Q

what are the advantages to in vitro produced (IVP)?

A
  • increased # of offspring from valuable females
  • offspring from otherwise infertile valuable females
  • offspring from sub fertile males
  • offspring from deceased animals (collect ovaries from deceased cow), stored frozen semen
25
Q

what are the disadvantages to in vitro produced (IVP)?

A
  • early embryo manipulation increased embryo mortality and malformations (large offspring syndrome)
  • costly (equipment)
26
Q

how do you get the oocytes for IVP?

A
  • abattoir (aspiration or slicing)
  • in vivo aspiration (transvaginal OPU)
27
Q

what do we use for IVP? what are they made of? how do we grade them?

A

cumulus-oophorus complexes (COCs)

made of immature oocytes + granulosa cells

Grade A to D

28
Q

For IVP:
1. maturation involves what?
2. fertilization involves what?
3. what happens on day 2 and day 7?

A
  1. expansion of granulosa cells
  2. incubation w/ capacitated sperm
  3. day 2 = cleavage = viable
    day 7 = blastocyst (embryo classification)
29
Q

true or false: there is a well established procedure for bovine IVP/IVF

A

true

30
Q

true or false: there is a well established procedure for equine IVP/IVF

A

false - not possible yet

31
Q

what are the 2 cryopreservation methods?

A
  1. slow freezing
  2. vitrification
32
Q

what is slow freezing?

A

controlled-rate freezing – dehydration of cells to avoid osmotic shock and intracellular ice formation

equipment $$ and time (1-2h)

33
Q

what is vitrification?

A

transformation of a solution into a glass-like state

ultra-rapid cooling - outruns ice crystal formation

no special equipment, quick to run

34
Q

what is the best cryopreservation method for both oocytes and embryos?

A

vitrification

35
Q

what is ICSI? when is it used? it is necessary?

A

intracellular sperm injection
used in some IVP/F protocols
not necessary but improves fertility

requires expensive equipment

36
Q

briefly describe sperm freezing

A
  • varies b/t species (some sperm freeze better than others)
  • simple procedures (field = liquid nitrogen box and dry ice block)
  • advanced freezing systems available
  • commercial freezing media (egg-yolk and milk based)
37
Q

briefly describe the epididymal sperm collection process

A
  1. ligate ductus deferens
  2. rinse w/ sterile saline
  3. cooling slows metabolism
  4. dissect epididymus
  5. recovery of sperm
  6. centrifuge to remove debris
  7. cryopreserve sperm
38
Q

what are 2 ways to recover sperm during epididymal sperm collection? which one is most used?

A
  1. retrograde flush technique - most common
  2. float up technique

541 (sex class) (22 decks)

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