Open Cow Test

Management of the Open Cow by Day 18 Following Artificial Insemination

At a Glance

Researchers at the Animal Reproduction and Biotechnology Laboratory (ARBL) at Colorado State University have developed an accurate and rapid test for earlier detection and management of ruminant pregnancies. This test platform allows for detection of pregnancy as early as day 15 with peak detection on days 17-19, allowing non-pregnant (open) cows to be re-bred much sooner than current standards. When compared to ultrasound diagnostic of pregnancy status at 32 days, this revolutionary method will improve pregnancy rates earlier in the lactation cycle, and increase annual milk production, longevity and profitability.


Dairy cows in the United States of America have pregnancy rates of only ~40% on their first breeding by Artificial Insemination (AI) following calving. The gold standard method for pregnancy diagnosis is using rectally-guided ultrasound on day 32 or later after AI. Additionally, the later in lactation that a pregnancy occurs each year, the less milk production and financial return per cow in the herd. Using the described early detection methods, this test will assist in producing pregnancy 2-3 weeks earlier in lactation compared to cows managed by current methods. Getting cattle pregnant earlier in lactation will result in greater overall milk and calf production in subsequent years and contribute to the longevity of cows in the herd, as well as avoid costly delays in re-synchronizing and re-breeding open cows.

With over 9 million dairy cows in the United States, this diagnostic will provide the ability to re-breed open cows so they enter the next lactation and produce milk faster, thereby increasing annual revenues for the dairy industry.


The developed Open Cow Test (OCT) utilizes a novel swab device to collect secretory fluid. The sample is prepared to analyze identified biomarkers of ruminant pregnancy and read via an enzyme-linked immunosorbent assay (ELISA) or a lateral flow immunosorbent assay to distinguish open from pregnant cows. Furthermore, the OCT may be used to identify cows that are experiencing embryo mortality.


  • The new swab device is more accurate and collects more antigen than other swabs
  • Swab samples can be collected by anyone versed in bovine artificial insemination techniques
  • No need for needles, blood tubes and a centrifuge
  • Assay (ELISA) completion time is approximately 5 hours (developed and available) in the laboratory or less than an hour using cow-side lateral flow analysis (under development)
  • 2-3 week earlier detection of ruminant pregnancy compared to ultrasound
  • 97% Negative Predictive Value and 5% False Negative rate when identifying non-pregnant (open) cows on day 17 following AI.
  • A higher likelihood of cattle that become pregnant earlier in the lactation cycle because of management of the open cow as early as day 17 following AI
  • Improved productivity of the herd because of rebreeding at second AI at least 2 weeks earlier compared to ultrasound, thereby leading to increased profit.
  • Future study and management of embryo mortality cows, possibly by day 17 following AI or by DNA testing for cattle that have a pre-disposition to embryo mortality.
  • Seeking a partner to use the new swab device in a larger clinical study (500-1,000) cows.


  • Livestock reproduction
Last Updated: March 2023
A picture of grazing cattle

Available for Licensing
TRL: 5

IP Status

US Provisional Patent


Thomas (Tod) R. Hansen
Hana Van Campen
Jeanette V. Bishop
Aydin Guzeloglu

Reference Number
Licensing Manager

Steve Foster