Do Cows Have Eggs? Exploring the Foundation of Cattle Reproduction

Jan 16, 2025

By Diane Broek

If you’ve ever wondered, “Do cows have eggs?” the answer is yes—but not quite the kind you’re picturing. Unlike chickens, cows don’t lay large, shell-covered eggs. Instead, they produce microscopic structures called oocytes—the foundation of reproduction. Though small enough to resemble a speck of dust, these oocytes play an essential role in the cattle reproduction process.

At Trans Ova Genetics, we work with these incredible “eggs” to help farmers and ranchers achieve their breeding goals through advanced reproductive technologies like embryo transfer (ET), in vitro fertilization (IVF), and cloning.

Let’s dive into the fascinating world of oocytes and their importance in modern agriculture.

What Is a Cow “Egg” or Oocyte?

An oocyte is an immature egg cell found in the ovaries of female cows. This tiny powerhouse is vital for reproduction, and here’s why:

Essential for Fertilization: When an oocyte is fertilized by sperm, it can develop into an embryo, a fetus, and ultimately, a calf.
Part of the Estrous Cycle: Oocytes are released during ovulation, which occurs roughly every 21 days in cows.
Scientific Applications: Oocytes are key to advanced reproductive technologies like ET, IVF, and cloning, helping to optimize breeding strategies and genetic progress.

How Does Trans Ova Work with Oocytes?

At Trans Ova Genetics, we harness the potential of oocytes through innovative reproductive tools that allow producers to maximize their herds. Here’s how:

Embryo Transfer (ET)

In ET, fertilized embryos are collected from donor cows through a process called flushing.

Process: A catheter is used to collect fertilized embryos from the uterine horn of the donor.
Frequency: This procedure can be done every 45–60 days.
Goal: Transfer these embryos to recipient cows, also known as surrogates, who will carry the calf to term.

In Vitro Fertilization (IVF)

IVF is a cutting-edge process where oocytes are fertilized in a lab rather than inside the cow.

Process: Unfertilized oocytes are collected from donor cows through a technique called OPU (ovum pick-up). Using a transvaginal guided probe, technicians aspirate the oocytes directly from the ovaries.
Frequency: OPU can be performed as often as every two weeks.
Result: Fertilized embryos are cultured in a petri dish before being transferred to recipients.

Cloning (SCNT)

Oocytes are also central to the cloning process, known as somatic cell nuclear transfer (SCNT).

How It Works:
- First, oocytes are harvested and enucleated, removing their genetic material.
- Then, the oocyte’s “bag of cytoplasm” receives a diploid cell from the donor’s genetic preservation.
- After that, the oocyte is jump-started through electrofusion, leading to the creation of a cloned embryo.
Purpose: Cloning allows for the replication of elite animals, ensuring their genetic traits are preserved for generations.

Why Oocytes Matter

Although small, oocytes are arguably the most critical component of cattle reproduction. At Trans Ova Genetics, we view these microscopic structures as the building blocks for:

Embryo Transfer
In Vitro Fertilization
Cloning

Their versatility allows farmers and ranchers to:

Produce more calves from their best donor cows.
Achieve higher genetic progress.
Optimize breeding strategies for better herd management.

What Came First: The Cow or the Oocyte?

The unsung hero of cattle reproduction, the humble oocyte, may hold the answer to this age-old question. Without oocytes, there would be no calves—and no progress.

At Trans Ova Genetics, we celebrate these tiny giants and their role in shaping the future of agriculture. Whether you’re breeding for milk production, beef traits, or genetic preservation, oocytes are at the heart of every success story.

Curious about how oocytes could help your herd? Contact us today and learn how our advanced reproductive technologies can help you breed your next generation of progress.