MOET

Multiple Ovulation Embryo Transfer (MOET) is the traditional form of embryo transfer. With MOET, donors receive a series of hormone injections, cycle and are mated (usually AI). The embryos are "flushed" out 7 days later and can be frozen or implanted fresh.

MOET Advantages

• It gives higher pregnancy rates

• It results in lower cost calves

• It can be carried entirely on-farm, in a single visit, without access to a lab.

MOET limitations

• MOET can't be carried out on pregnant cows

• It tends to delay conception (re-breeding)

• It doesn't work so well with sexed semen

• Because of the potential delay of getting donors back in calf, it is less suitable for young cattle if carried out within the breeding season.

• It requires more work by the farmer

• It requires that donors receive hormone injections

IVF

In-Vitro Fertilisation (IVF) 

IVF works by harvesting unfertilised eggs (oocytes) directly from the donor's ovary using OPU / TVR or (with recently dead donors) genetic recovery.

The oocytes are fertilised in the IVF lab and cultured for 8 days. Following this, they can be frozen or transferred fresh.

IVF advantages

• It can be carried out on pregnant cows, recently dead cows and younger heifers

• can be done as often as once a week

•  Oocytes from one pick up could be split and go to different sires 

• It works well with sexed semen

• No hormones need to be administered to donors

• Lower workload for farmers

• Lower impact on short-term fertility

IVF limitations

• Per calf, it is more expensive than MOET

• Pregnancy rates are usually lower than MOET

• It requires multiple visits to a farm 

• Management is needed at calving to address large calves - normally <5%

On-centre 

Both MOET and IVF donors can be sent to centres for collection - although MOET programs may be limited. 

Donors are usually sent to centres if

• A farmer has fewer than 5 donors

• The animals are in an isolated area 

• The animals require several sessions to meet targets

• Farmers want to simplify their systems and reduce workload - such as dairy farmers whose heifers are with a grazier

On-farm

Donors are usually collected on-farm when

• Farmers wish to avoid biosecurity risk (closed herds)

• Farmers are collecting from a large number of donors

• Recipients are also on-farm