Pregnancy Detection

Pregnancy Detection in Beef Cattle

Pregnancy detection (preg-checking) has been used in the beef industry for more than 60 years and plays a crucial role in breeding cow management. There are many reasons for producers to preg-check including to evaluate herd and bull fertility, to help monitor herd reproductive health, to determine approximate calving dates and to help determine how best to sort cows into management groups.

Preg-checking also gives producers the opportunity to save the cost of overwintering non-pregnant (open) cows, especially in years when pasture conditions are poor, or feed is costly. Heat detection alone is not enough to determine pregnancy as there is a high chance of missing cows in estrus or cows showing estrus after they have been bred (false heat). 

Key Points
Several methods can be used for testing pregnancy in cattle, including ultrasound, manual palpation, and blood samples.
Generally, producers have three options for managing open cows:
-Preg-check cows in the fall and cull opens immediately
– Preg-check in the fall and feed open cows separately to market at a later date
– Do not preg-check – overwinter all cows together and cull opens in the spring after the herd has finished calving
Preg checking and culling cows in the fall is more favourable when feed and overwintering costs are higher.
Cull cow average daily gains (ADG) over the winter-feeding period have a significant impact on the cow’s spring value; regardless of the market price, higher weight gains over the winter result in higher spring values than low weight gains, regardless of the market price.
The seasonality of cow prices is a stronger driver of the economics of preg-checking than winter feed costs.
Consistently higher cull-cow prices in the spring can be a strong deterrent to preg-checking
When cow prices have strong seasonal increases from fall low to spring high, the strategy of preg-checking and feeding the open cow group a high-energy ration for 90 days provides the greatest economic benefit to producers.
When cull cow prices drop below $0.75/lb, many scenarios indicate that preg-checking and culling in the fall is a better option as the cost of overwintering begins to outweigh the benefit of selling heavier cull cows in the spring.
Preg-checking allows the opportunity to provide booster vaccines and update your Vet-Client-Patient Relationship (VCPR) with your veterinarian including herd health programs such as vaccine protocols.
Preg-checking allows for earlier detection of potential reproductive wrecks or a higher-than-expected open rate.
Preg-checking and then removing non pregnant animals from the main cow herd prevents the chance of injury that may occur when cycling cows are riding heavily pregnant cows.

Methods of Pregnancy Detection

Several methods can be used for testing pregnancy in cattle such as, ultrasound, manual palpation, and blood samples1,2.

Manual palpation

Palpation can determine pregnancy as early as 35-45 days by feeling the uterus and ovaries through the rectal wall. Experienced veterinarians can estimate stage of pregnancy and approximate the calving date.

Having a defined breeding season and removing bulls from a breeding pasture weeks before preg-checking will help to increase testing accuracy and eliminate the question of whether cows are open or bred fewer than 45 days before the exam.

Ultrasound

Ultrasound uses a probe to emit and receives sound waves aimed at the uterus to create an image. When sound waves contact solid tissue, like bone, they bounce back and appear white on the monitor. Sound waves pass through fluids and therefore do not return to the probe appearing black in the image. Various densities of tissue appear in shades of grey.

Ultrasound can detect pregnancy as early as 13-21 days, with limited accuracy. When done by an experienced vet, ultrasound is recommended after 25 days. It is important to note that early pregnancy diagnosis does not guarantee a birth. The majority of pregnancy loss occurs in early embryo development (the first month of pregnancy)3. Though there is a risk of pregnancy loss at any stage of gestation, preg-checking after the first month may provide more accurate results.

Pregnancy detection with ultrasound requires less manipulation of the uterus, and previous studies have shown that pregnancy loss was 1% lower in heifers that were preg-checked using ultrasound vs. manual palpation4. However, fetal age and technician experience can also affect pregnancy loss.

Compared to manual palpation, ultrasound is also more accurate at determining fetal age, can determine viability of the pregnancy, detect twins, and identify the sex of the fetus(es).

Blood samples

Detecting pregnancy with blood samples uses a lab test that detects pregnancy specific proteins. The blood sample can be taken by a producer from the tail vein and sent to a lab for analysis. Pregnancy testing through blood tests works well for producers with limited access to veterinarians.

Blood samples can be taken as early as 28 days and there is no risk of transferring venereal diseases between cows. Because samples must be sent to a lab for analysis; results may not be returned to producers for days or weeks.  Therefore, cows will need to be brought in twice if producers want to cull non-pregnant cows or sort cows into management groups based on pregnancy. Additional considerations are cost and access to a lab to perform the test. 

Economics of Pregnancy Detection 

Across Canada the percentage of producers that include preg-checking as part of their management strategy ranges from 50% to 76% depending on the region being surveyed5. Though this number has increased since the late 1990’s, in some provinces half of producers do not preg-check cattle. This is often due to economics or the perceived cost savings of not having a vet do pregnancy detection. A closer look at the options for managing open cows and the associated pros, cons and resulting economics is important6.

Assuming a spring calving schedule, generally producers have three options for managing open cows:

1)     Preg-check cows in the fall and cull opens immediately

  • Pros: Realize value of cull cows in the fall and avoid incurring costs of overwintering open cows. 
  • Cons: Incur vet costs and forgo the value of cull cows in spring during higher market prices.

2)     Preg-check in the fall and feed open cows separately to market at a later date

  • Pros:  Avoids selling during the lower market prices during the fall and adds weight to cull cows before they are sold. 
  • Cons: Incur vet costs, absorb overwintering costs for open cows, and supplemental feed costs.

3)     Do not preg-check, overwinter all cows together and cull opens in the spring after the herd has finished calving.  

  • Pro : Reduce vet costs
  • Con: Feed non-pregnant cows throughout the winter. It is not likely that fees saved on vet costs will cover winter feeding for non-pregnant animals.

The economics of preg-checking and selling cull cows depends on:

  • cull cow market price,
  • the management system employed by the producer,
  • feed and overhead costs, and
  • veterinary costs. 

Calculator: Economics of Pregnancy Testing Beef Cattle

Economics of pregnancy testing calculator.

To help beef cattle producers choose the most economical option for their operations, an economics of preg-checking model was developed by Ben-Ezra and Muzzin (2015). The Economics of Pregnancy Testing Calculator was developed by Canfax Research Services in 2016 and updated in 2023.

The model accounts for several factors and assists cow-calf producers in determining which of the three above options makes the most sense for their operation.

Basic and advanced versions of the calculator are available. The advanced version is recommended for producers who would like to tailor their individual on-farm cost of production and expected average daily gains when feeding cull cows as a separate group.

Economics of preg-checking depends on overwintering costs, cull cow ADG and market price. During drought years, preg-checking and culling open cows is one tool to reduce herd size and corresponding pressure on feed and forage.

Resources on the Introduction Record Keeping and Benchmarking page at BeefResearch.ca can help you decide which records to keep in order to make informed decisions on your operation.

Value of Calving Distribution

Each time a cow is not bred during a 21-day heat cycle, it can cost up to 39 lbs of weaning weight (assuming an average daily gain on calves of 1.85 lbs/day). This calculator will allow producers to see what their current calving distribution is, and what the impact on your revenue would be if they move to the industry target of 60-25-10-5, or a condensed breeding season of three cycles. Early preg-checking may help with decisions on culling cows expected to calve late and assist in tightening the calving season in system where managing the breeding season length is not feasible.

Click to use the calculator.

Value of calving distribution tool

Benefits of Pregnancy Detection

Although less easily measured, there are many other benefits of having your veterinarian preg-check cattle in the fall:

  • Allows the opportunity to provide booster vaccines and update your Vet-Client-Patient Relationship (VCPR) with your veterinarian including herd health programs such as vaccine protocols.

  • Can detect potential concerns during palpation including abnormalities of the reproductive tract or the occurrence of twins

  • Allows for earlier detection of potential reproductive wrecks or a higher than expected open rate.

  • Provides an opportunity when handling animals to provide internal and external parasite control.

  • Is the perfect time to do hands on body condition scoring.

  • Removing non pregnant animals from the main cow herd prevents the chance of injury that may occur when cycling cows are riding heavily pregnant cows

  • Gives an opportunity to make sure ear tags are still in place and legible

References

1 Smith, Thomas, H. 2010. Pregnancy Checking Tips. The Beef Magazine. Available here.

2 Smith Thomas, H. 2015. Preg testing cows is easier than it used to be. Canadian Cattlemen Magazine. Available here.

3 Reese, S.T., Franco, G.A., Poole, R.K., Hood, R., Fernandez Montero, L., Oliveira Filho, R.V., Cooke, R.F., Pohler, K.G. 2020. Pregnancy loss in beef cattle: A meta-analysis. Animal Reproduction Science 212 (2020). doi: 10.1016/j.anireprosci.2019.106251. Available here. 

4 Richardson, R.D., Mortimer, R.G., Whittier, J.C. 2010. Comparison of fetal losses from diagnosis of pregnancy using ultrasonography or rectal palpation in beef heifers by novice or experienced technicians. The Professional Animal Scientist 26 (2010): 341-346. doi: 10.15232/S1080-7446(15)30613-6

5 Pearson, J.M., Pajor, E.A., Caulkett, N.A., Levy, M., Campbell, J.R., Windeyer, M.C. 2019. Benchmarking calving management practices on western Canada cow-calf operations. Translational Animal Science. 2019.3: 1446-1459. doi: 10.1093/tas/txz107. Available here.

6 Muzzin, A., Ben-Ezra, E. 2015. An economic model for cow-calf producers to determine the cost-benefit of pregnancy testing. Prepared for CanFax Research Services. Available here. 

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Acknowledgements

Thanks to Dr. Juan Hernandez-Medrano, University of Calgary Faculty of Veterinary Medicine, for contributing their time and expertise to reviewing this page.

This content was last reviewed January 2025.