Therio - Bovine - ART

drraythe's version from 2017-09-10 03:45

Assisted Reproductive Technologies (ART)

Question Answer
What are 4 good reasons why embryo transfer (ET) is a desirable thing to do?(1) Increased progeny from genetically superior dams
(2) International trade (easier to ship an embryo)
(3) Dz control
(4) Genetic salvage of valuable individuals
What is MOET?Multiple Ovulation & Embryo Transfer
What are ways that embryo transfer is able to allow Genetic salvage of valuable individuals?Freezing of embryos, infertile animals
Basic outline of how MOET (mult ovulation & embryo transfer)Selection of the donor cows
Super-ovulation of donor cows
Synchronization of donor & recipient
Insemination of the cows
Flushing of the embryos (surgical vs non-surgical)
Evaluation of the embryos (embryo grading)
Selection & preparation of recipient females
Transfer of the embryos
What factors would possibly influence that a cow would be selected as a donor cow?Genetic superiority, Reproductive soundness (Healthy, cycling animals w/ No Hx of reproductive problems), No Dzs, 60+ days post-partum, Vxs current
What are 2 methods of Super-ovulation of donor cows? (Explain a little)(1) FSH products- czs a whole lot of follicles to be selected & recruited. FSH products have a short half-life & you will need BID (2x d) Injxns
(2) eCG products- only need 1 Injxn. Work similar to FSH
**How well should a donor & a recipient’s cycle line up for an embryo transfer process?NB! Close synchrony btwn. Donor & recipient → Recipient in estrus 36h before to 12h after donor
*If you have 1 donor cow, how many recipients do you need?8
*WHEN do you flush the embryos from the donor cow?Day 6-8 post estrus
Embryo grading works on a scale up to what, & what does each grading mean? What exactly is being graded?Embryos graded as to the potential likelihood of success after transfer. Grade 1 - Excellent or good
Grade 2 - Fair
Grade 3 - Poor
Grade 4 - Dead or degenerating
Embryos are also evaluated for their stage of development- what is this scale like?Stages 1-9:
Stage 1 is a unfertilized egg
Stage 2 is 2-12 cells
Stage 3 is early morula
Stage 4 is morula
Stage 5 is early blastocyst
Stage 6 is blastocyst
Stage 7 is expanded blastocyst
Stage 8 is hatched blastocyst
Stage 9 is expanded hatched blastocyst
Which stages of development of the embryo are ideal for transferring or freezing? (Number & what number means)Stages 4, 5, & 6, which are: morula, early blastocyst, blastocyst (clump, clump w/ a little space in it, clump attached to hollow ball)
What are some reasons as to why Dz Xmission risks are reduced w/ embryo transfer?The Zona pellucida is Difficult for pathogens to penetrate/adhere, The embryo is only exposed to a very restricted environment, the embryo is super small & lacks body systems that a pathogen might be interested in.
What are some steps taken to further reduce the risks of Dz Xmission w/ embryo transfer?Washing of embryos (10x), Wash w/ trypsin, ABx in medium, & Evaluation of embryos to ensure ZP intact & free of adherents
What does OPU stand for?Ovum Pick Up
What is going on during OPU (ovum pick up)Use a special ultrasound probe in vagina of cow to visualize. Then take a needle w/ suction device & stab through ovary to pick up oocytes-- getting 1° follicles. (Use in vitro maturation medium to grow mature follicles, do in vitro fertilization/culture, & then implant embryos into donor cow)
What does IVF & IVP stand for?In Vitro Fertilization & In Vitro Production
Explain what happens in In Vitro Fertilization & In Vitro ProductionDonor cows → OPU (ovum pick up) → in vitro maturation → fert w/ sperm → embryo culture for 7d, collect blastocysts → then either embryo freezing or embryo transfer → birth of calf
When is Large Calf Syndrome usually seen?Seen more often w/ in vitro production calves
What problems constitute Large Calf Syndrome/Large Offspring Syndrome?Increased birth weight (15%+), Developmental abnormalities w/ placenta, Increased incidence of abortion, Dystocia
What do they think the problem is w/ large calf syndrome?Thought to be a problem w/ culture media
Explain how Sex-Sorted Semen worksX chromosomes contain 4% more DNA than Y chromosomes, so they are just slightly heavier/bigger & you can use flow cytometry to sort them (+/- 10 million sperm /hour w/ 90% accuracy)