The IVF Process

In vitro fertilization (IVF) has become a reliable and widely used tool for cattle breeders. While it offers several advantages over conventional embryo flushing, it can feel a bit confusing at first. The technology behind IVF is advanced, but the process itself is often more straightforward than people expect—especially when it’s well explained and properly managed. Our goal at StillGrass is to make IVF approachable and easy to understand so you can decide how it fits into your breeding program.

Step 1: Oocyte (Egg) Collection

The IVF process begins with collecting oocytes (eggs) from the donor female, a procedure commonly called oocyte pick-up, or OPU. Eggs are collected directly from the ovaries using ultrasound guidance and a specialized needle connected to a gentle vacuum system. While that may sound complicated, the procedure is typically quick and usually takes about 15–20 minutes.

One of the biggest advantages of IVF is flexibility. Donors can be collected at many stages, including during pregnancy or shortly after calving. Superovulation can be used before collection in some cases, but it isn’t required and depends on the individual animal and goals of the program (we’ll write another article on this topic alone).

Step 2: Fertilization in the Lab

After collection, the oocytes are taken directly to our in-house laboratory. The eggs are matured and then fertilized the following day using the semen of your choice. Sexed semen can be used to influence the sex of most embryos.

Because a single straw of semen can fertilize oocytes from multiple donors, IVF is also a practical way to maximize the use of that expensive straw of semen in the tank.

Step 3: Embryo Development

Once fertilized, embryos are cultured in a carefully controlled laboratory environment for about seven days. During this time, incubators maintain precise temperature, humidity, and gas levels to support healthy development. Around day six, we can often provide an early estimate of how many embryos are likely to be suitable for use the following day.

Step 4: Fresh Transfer or Freezing

Viable embryos can either be transferred fresh into recipient females or frozen for future use. Embryos are typically ready on day eight after oocyte collection. For fresh transfers, having the recipients timed up correctly is important. We’re happy to provide synchronization protocols and timelines when using fresh embryos. In general, recipients should come into heat on the day of, or the day after, the donor’s oocyte collection.

A Practical Tool for Genetic Progress

IVF allows breeders to multiply elite genetics, shorten generation intervals, and utilize donors that may not be ideal candidates for conventional embryo flushing. When paired with thoughtful planning and veterinary oversight, it can be an effective and flexible tool for moving a breeding program forward.