ART Flashcards
describe the sex-sorted sperm process
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
describe how you use AI in cattle
intra uterine, horn
frozen most common
describe how you use AI in pigs
trans-cervical
fresh or cooled
describe how you use AI in small ruminants
vaginal (fresh), cervical (fresh), uterine (laparoscopy, frozen)
what are the pros of AI
- widespread use of superior males and quicker genetic gain
- use of genetic material across geographic distances
- disease control
- reduced possibility for injury (valuable sires)
what are the cons of AI
- 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
what are the pros to using sex sorted sperm?
- more sustainable prod systems
- breed genetically superior animals for replacement
- decrease calf wastage (ex. dairy bull calves)
what are the limitations to using sex sorted sperm?
- 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%
describe how you use AI in horses
- 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
describe how you use AI in dogs
- vaginal (fresh and cooled)
- laparascopy (frozen)
- fertility: lap > vag
- transcervical (endoscopic)
what is most important when using AI in dogs?
knowledge of dog estrus cycle (LH surge, cytology, P4 concentrations, vaginoscopy)
which species have the highest ET?
cattle
what are the 2 types of embryo transfer?
in vivo derived (IVD) and in vitro produced (IVP)
IVD: fertilization happens in the female
IVP: egg harvested and fertilized outside of female
why do we use ET?
- 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)
what are the problems with ET?
- 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
how do the pregnancy rates of ET compare with AI?
% preg rate lower or comparable to AI
briefly describe IVD - MOET.
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
how many embryos does it take for ET to have a good and excellent response in cattle?
good: 6-9 embryos
excellent: 10-20 embryos
long story short, the more embryos, the more success
ET is useful in cattle with what factors?
repeat breeders
cows under heat stress
when using ET, the donor should be synchronized to what days?
day 6-7
ET fertility fresh vs frozen
fresh > frozen
usually code ____ & ____ transferred fresh and possible frozen with ET
1 & 2
success of ET depends on what factors?
- 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)
what are the advantages to in vitro produced (IVP)?
- 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
what are the disadvantages to in vitro produced (IVP)?
- early embryo manipulation increased embryo mortality and malformations (large offspring syndrome)
- costly (equipment)
how do you get the oocytes for IVP?
- abattoir (aspiration or slicing)
- in vivo aspiration (transvaginal OPU)
what do we use for IVP? what are they made of? how do we grade them?
cumulus-oophorus complexes (COCs)
made of immature oocytes + granulosa cells
Grade A to D
For IVP:
1. maturation involves what?
2. fertilization involves what?
3. what happens on day 2 and day 7?
- expansion of granulosa cells
- incubation w/ capacitated sperm
- day 2 = cleavage = viable
day 7 = blastocyst (embryo classification)
true or false: there is a well established procedure for bovine IVP/IVF
true
true or false: there is a well established procedure for equine IVP/IVF
false - not possible yet
what are the 2 cryopreservation methods?
- slow freezing
- vitrification
what is slow freezing?
controlled-rate freezing – dehydration of cells to avoid osmotic shock and intracellular ice formation
equipment $$ and time (1-2h)
what is vitrification?
transformation of a solution into a glass-like state
ultra-rapid cooling - outruns ice crystal formation
no special equipment, quick to run
what is the best cryopreservation method for both oocytes and embryos?
vitrification
what is ICSI? when is it used? it is necessary?
intracellular sperm injection
used in some IVP/F protocols
not necessary but improves fertility
requires expensive equipment
briefly describe sperm freezing
- 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)
briefly describe the epididymal sperm collection process
- ligate ductus deferens
- rinse w/ sterile saline
- cooling slows metabolism
- dissect epididymus
- recovery of sperm
- centrifuge to remove debris
- cryopreserve sperm
what are 2 ways to recover sperm during epididymal sperm collection? which one is most used?
- retrograde flush technique - most common
- float up technique
