• A bovine heifer calf is generally born with 10,000 to 350,000 healthy follicles and ova in their ovaries.
• Only a small proportion of these oocytes ever have the opportunity to form an embryo in the natural reproductive life cycle of a cow.
• Historically the adoption of Multiple Ovulation Embryo Transfer (MOET) techniques have increased genetic gain through the production of more offspring from superior animals.
• More recently Ovum pick up (OPU) and in vitro embryo production (IVP) has been shown to increase the frequency of ova collection relative to MOET, as ova can be aspirated once or even twice weekly and during the first trimester of pregnancy.

Uses

• Advanced reproductive technology for the collection of cumulus oocyte complexes (COCs) for in vitro embryo production in cattle lines of superior genetic quality.

Advantages

• A reduced loss of female germplasm occurring through the natural process of ovarian follicular atresia.
• An increased yield of embryos from elite donor cows, beyond that possible with superovulation.
• Recovery of oocytes from pregnant cows, within the first trimester.
• Recovery of oocytes from cows with salpingitis, non-patent oviducts, or those which no longer produce embryos in vivo.
• Use of less semen that conventional breeding or MOET and an opportunity to use many more bulls on one donor over a space of time allowing greater selection potential
• A means of salvaging genetic material from valuable animals at slaughter or those culled for disease control.
• Ovum pick-up does not require the animal to have a normal reproductive cycle and thus, when used in conjunction with IVF technology, greatly increases the possibility of shortening the generation interval and increasing genetic gain through the production of more progeny per year than possible under normal circumstances.

Disadvantages

• Availability of trained, experienced veterinary personnel to undertake the OPU procedure and embryologists to undertake in vitro embryo production.

Technical problems

• Approximately 80% of COC’s start to develop with a blastocyst recovery rate of approximately 45% of those which start to cleave. Reasons include:
  • The embryo culture system.
  • COC quality.
  • Cleavage rates and blastocyst quality.
  • Number of embryos per recipient.
  • Synchrony of embryo development with recipient day of estrus cycle.
  • Type of embryo (fresh vs. frozen).
  • Environmental factors such as heat stress and nutrition.
• Previous problems associated with OPU and in vitro fertilization such as large calf syndrome or other fetal abnormalities were associated with components of the initial culture media and have now been overcome.