A Bulk Tank Test to Estimate Bovine Leukosis Prevalence in Your Herd

In recent years, it has been possible to use bulk tank milk to estimate the prevalence of bovine leukosis in a herd.
A first round of tests of all Quebec dairy herds was conducted in 2017 at the request of the Producteurs de Lait du Québec (PLQ). The objective was to raise producers’ awareness of the impact of the disease on their herd’s health.

The bulk tank tests allow the classification of the herds into 3 categories:

  • Herds with low prevalence
    • Percentage of cows that tested positive for bovine leukosis: 0 – 10% 
    • Insignificant impact on herd health
  • Herds with medium prevalence
    • Percentage of cows that tested positive for bovine leukosis: 10 – 30% 
    • Significant impact on herd health
  • Herds with high prevalence
    • Percentage of cows that tested positive for bovine leukosis: 30% and up  
    • Major impact on herd health

In addition to increasing the awareness of leukosis prevalence in the herd, bulk tank tests help to better target the most relevant biosecurity measures to be implemented and to guide producers towards the most optimal individual testing strategy.

A new round of testing began in January and will continue until June to update the disease prevalence in Quebec livestock. To keep the process simple, standardized and seamless, the tests are performed on samples collected by the milk truck driver as part of the PLQ’s quality control program. The results will be distributed on the Lactanet MySite portal.

Understanding My Report

First Section

 First, the bulk tank test report shows you the result of your most recent test: 

  1. Bulk Tank Sample Collection Date: The sampling date by your trucker. 
  2. Estimated Prevalence in my HerdThis value is calculated from the analysis result. 
  3. 95% Confidence Interval: This range represents the range in which your herd should be located considering: 
    • The accuracy of the laboratory analysis 
    • The cows’ contribution to the bulk tank  
    • The level of positive status of each cow 
  4. A graphic representation will then allow you to place you according to the three categories mentioned above (see first box). 

Second Section

The following section of the report shows you the economic loss associated with bovine leukosis in your herd. The calculation takes into account the prevalence of the disease, the size of your herd and your production data.

This will allow you to gain a better understanding of the situation and validate the economic impact of reducing the disease in your herd.

If the amount does not appear on the report, it is because the information required to perform the calculation for your herd is not available in our database. You can then access a simple calculation tool by contacting Lactanet customer service or by consulting your veterinarian.

Third Section

Finally, at the bottom of the report, you will be able to see the result of your first round of testing (over 4 years ago):

PISAQ Campaign to Help You

MAPAQ has set up a PISAQ campaign to support advisory services to enable you to protect or improve the status of your herd with respect to bovine leukosis through free access to your veterinarian.

Take this opportunity to invest in the health and profitability of your herd. Together, we can fight back against bovine leukosis!


By Jean Durocher, M. Sc., D.M.V.
A graduate of the Faculty of Veterinary Medicine of the Université de Montréal, Jean is an excellent communicator and has contributed to the training of many veterinary practitioners from around the world on embryo transfer and ultrasound techniques.