Assisted Repor: Artificial Insemination (A.I.) and Embryo Transfer (E.T.) Flashcards
(31 cards)
Artificial insemination
Bovine, Equine, Canine, Ovine, and other species
Sperm is collected from the maile and placed into the female reproductive tract to join with a naturally ovulated egg
Sex-Selected semen
Bovine and Equine
Sperm is sorted by flow cytometry into predominantly X-bearing sperm and predominantly Y-bearing sperm aliquots
the sorted sperm is then used for AI
Embryo Transfer
Bovine and equine most commonly
AI or natural service is used to inseminate a female
The resulting embryo(s) are collected prior to the time of “hatching” from the zona pellucida and transferred to the different female (recipient) ofr the rest of gestation
In vitro Fertilization
Becommong Common
A single sperm cell is inserted into an egg in a laboratory environment
Embryo is cultured on artificial bedia of several days and if the embryo proceeds to the blastocyst stage - it is transferred inot a recepient (donor or another female) for the rest of gestation
Gamete Intra-Fallopian Transfer (GIFT)
Mostly experimental
An egg is aspirted from a donor female’s ovary prior to ovulation and then planced in the uterine tube of a recipient
THe recipent is bred naturally or via AI
Embryo-splitting
Bovine and Equine
Identical twins (or more) can be produced by splitting a day -6 embryo (blastocyst before hatching from ZP) – and placing the fragments into empty ZP shells and then transferring them into recipients
Cloning (Nuclear transfer)
Bovine, ovine, canine, and equine
Multiple genetically identical animals can be produced by taking cells from an embryonic blastocyst and implanting them into enucleated oocytes which are transferred to a recipient
Cloning (Somatic Cell Nuclear Transfer)
Ovine, canine, bovine, and equine
Multiple genetically identical animals can be produced by taking an adult cell and “re-programming” it to allow differentiation into an entire organism when implanted into enucleated eggs
Artificial Insemination
Advantages
Genetic Improvement - Widespread use of males likely to produce valuable offspring (based on the sire’s performance) or proven to have valuable offspring (based on many documented offspring)
Can use males form anywhere in the world
Don’t have to have as many males
Remove/reduce risk of venereal disease
Artificial Insemination
Disadvantages
Skill of estrus detection
Trained insemination - skill that must be hired or learned
Time and skill to commit to herd/animal reproduction
Increased cost per pregnancy
Collecting Semen for AI
Semen can be purchased form commercial suppliers and directly from males owners
Semen can be collected on-site and used to mate many more females and at decreased risk of injury than via natural service
Bull, Dog, and stallion semen is frequently frozen - other species primarily use fresh or chilled semen
THe semen of some males does not freeze well - this is not necessarily related to fertility in natural service
Collecting semen for AI
Artificial Vagina
Males that are trained to mount a dummy or teaser animal
Bulls, Stallions
Stallion (temperature / pressure ejaculator) - AV has a jacket that is filled with warm water
Bulls (Pressure ejaculator) - AV does not need a warm water jacket
Collecting semen for AI
Electroejaculation
Males that are not trained to mount a dummy or teaser animal
Bulls, bucks, Wildlife
Specialized probe placed into the rectum applies a series of low-voltage pulses to the pelvic nerves involved in erection and ejaculation
Collecting Semen for AI
manual Stimulation
Pressure ejaculators - massage the penis
Dogs, boars, whales
Collection tube rather then true AV
Collecting Semen for AI
DO NOT USE
latex, plasitc, and lubricants can be detrimental to sperm viablility
Limit their use and contact time
Cryopreservation of sperm
Adequate fertility post-thaw requires:
Appropriate diluents / extenders
Non-penetrating cryoprotectant
Penetrating cryoprotectant to protect from ice cyrstal formation
Buffer to prevent pH change
Sugar to provide an energy source
Salt to provide proper osmolality
Antibiotic to kill pathogens
Cryopreservation of sperm
Adequate fertility post-thaw requires:
Appropriate Sperm Dilution
Bulls: 20 million sperm per dose - assume 50% live sperm post-thaw
Can use a lot less - but must thaw and place semen very well
Cryopreservation of sperm
Adequate fertility post-thaw requires:
Appropriate Cooling and Thawing Speed
Rapid Cooling - but in steps
Add some extender ingredients and cool from 102F to 40F - refrigeratation temp
Add cyroprotectants and package into 0.5 mL straws - hold at 40F for a few hours
Freeze in liquid nitrogen vapor at -238F
Store in liquid nitrogen until used -320F
Cryopreservation of sperm
Adequate fertility post-thaw requires:
Rapid Warming
Semen thawed at 95F for 12 seconds to one minute had best post-thaw viability
Semen thawed at 68F for 12 seconds to one minute has acceptable post-thaw viability
Semen thawed at 41F water bath or in a shirt pocket has lowest post-thaw viability
Artificial Insemination
Detection of Estrus
Used to estimate timing of ovulation
Difficult - great species-to-species viariability and animal-to-animal variability within a species
Artificial Insemination
Timing of Insemination
Canine
Fresh Semen
Ovulation occurs 1 to 2 days after LH surge
Wait longer to breed after ovulation
Fresh semen: lives 5-6 days in uterus
Breed 4-6 days after LH surge
Artificial Insemination
Timing of Insemination
Canine
Chilled Semen
LIves about 1-3 days after ejaculaiton
Will lose at least 1 day in shipping
Breed 4-5 days after LH surge
If breeding 2 times, breed at days 3 and 5; 4 and 6 post LH peak
Must plan ahead - order semen when she ovulates
Artificial Insemination
Timing of Insemination
Canine
Frozen semen
Lives about 12 hours in uterus
Breed 5-6 days after LH surge
no Problem with shipping at the last minute - have the semen on hand far in advance of breeding
Intrauterine insemination - surgical or transcervical catheterization
Artificial Insemination
Timing of Insemination
Bovine
Almost always utilize frozen semen
Successful breeding with frozen semen since 1940s
Fertility using forzen semen in equal to natural service
Semen is placed in the uterus - pipette is passed through the cervix
Breed approximately 12 h after first detection in esturs