Conventional Embryo Flushing
This older technique has been commercially popular since the early 1980’s. It involves the following:
- The injection of certain hormones (FSH), which causes a female donor animal to super-ovulate, that is to ovulate more than the customary one egg or ovum they normally do when on standing heat.
- The cow is then AI’ed when on heat and the eggs are fertilized, as during a normal heat, by the sperm in the fallopian tubes.
- Recipients or surrogate animals are synchronized with a hormone program to come on heat on the same day as the donor animal, but they are not AI’ed or mated.
- 7 days after fertilization, a catheter is placed in the uterus of the donor animal, and the embryos are flushed out with fluid, retrieved and classified under a microscope in a laboratory. The 7-day old embryos can then be transferred right away or be frozen for later use.
Conventional flushing – current industry standards
- Embryos obtained per flushing 6-8
- Conceptions with fresh embryo transfers 60%
- Conceptions with frozen embryo transfer 40-50%
- Can be repeated every 6-8 weeks, mostly for 2-3 cycles
- Usually invoiced per flushing done, regardless of number of embryos obtained
- Can only be done on non-pregnant animals, so sometimes the donor’s ICP is compromised if she has to wait for a flushing program before falling pregnant again.
- Donors with pathology to the uterus or both fallopian tubes cannot be used.
- Requires more input from the breeder, such as the injecting of the donors during the program, that needs to be accurate and on time, as well as the AI of the donors that is critically important.
- Donors receives certain hormones that, if not administered in the right way as prescribed by an expert, could lead to fertility problems later on, if used at excessive dosages or for too many programs in a cycle.
- Only semen of a very high quality can be used (poor fertilization usually achieved with sub-optimal semen or sex sorted semen in mature cows) and requires at least 3 straws of semen per donor per flush.
- Easier to implement currently in very remote areas or neighbouring countries without access to IVF laboratories.
- Some countries would only consider conventional embryos for imports.
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