Reproductive technologies Flashcards
AI to Sex Control
Artificial Insemination
Semen collected from males and can be used fresh, cooled, or frozen to breed females
Estrus Synchronization
Hormones used to induce females to come into heat at the same time
[PGF2 alpha, Progesterone, or GnRH]
Reduces number of days to inseminate
PGF2 alpha
Hormone
Regression of Corpus lutem and decrease in progesterone synthesis
Progestogen
Hormone
Feedback on hypothalamus by blocking LH and FSH hormones
GnRN (Gonadotropin Releasing hormone)
Hormone
Ovulation/luteinization of growing follicle
Embryo Transfer
Collection of embryos form donor females and transferred to recipient females
Donors are super ovulated and inseminated
Embryos are collected before implantation to be frozen or transferred
Issues with Embryo Transfer
Difficulty identifying candidates to be donors
Traits with maternal effects can be affect by recipient females (ex: brith or weaning wgt)
More costly and difficult than AI (still need to synchronize donor and recipe if using fresh embryos)
In Vitro Fertilization
Fertilization in test tube
Eggs collected and matured/incubated and fertilized in lab
Can be frozen or transferred
Egg Harvest
Ultrasound guided aspiration
Laproscopy (minimal invasive surgery)
Embryos tranferred at 8-cell stage or blastocyst stage into recipient
IVF Advantages
-Increased number of possible pregnancies
-Collect eggs repeatedly from same donor at short intervals
-Doesn’t have to be a certain stage of estrous cycle
-No need to super overate female
-Decrease Gi
-Eggs can be collected from immature females
IVF Disadvantages
-Expensive
-Success rate relatively low
-Abnormalities of offspring (Can trigger unwanted genes that are supposed to be silent)
Sex Control: Embryo
Possible to determine sex of embryo by physically removing a few cells and examining chromosomes
Two ways: Biopsy of Blastomere or Testing Maternal Blood Plasma
Sex Control: Sperm
Sperm sorting
Possible to sort sperm carrying X chromosome from sperm with Y chromosomes
Process is too slow to have sexed sperm still be viable
Flow cytometry
Measurement of cells as they flow by a detector
Sorts based on DNA content of sperm cells
-Semen labeled with fluorescent dye which binds to DNA
-X chromosome absorbs more dye thus glows brighter
-X and Y inversely charged and sorted by charge (Electrostatic deflection)
Sexed Semen for Cattle
Ability to separate X and Y sperm and produce desired sex of calf with 90% accuracy