BLV Herd Profile

Creating a BLV Herd Profile

The BLV herd profile is a useful management tool for monitoring the BLV status of your herd because it doesn’t require testing the entire herd. We’ve provided an Excel spreadsheet here that will calculate your BLV herd profile and provide you with a graph of your profile. You simply input the lactation number and test result for each of the 40 cows tested. For comparison, the graph also shows the lactation-specific prevalence and average rates for herds that were sampled in our National BLV study from 2014-2016.

For a full summary of creating and using the BLV herd profile see this PDF, and to download our Excel spreadsheet click here.


What is a BLV Herd Profile?

You would simply request that your DHIA or veterinary diagnostic lab to run a BLV ELISA test on milk samples from 40 cows. With the results of those tests, you can calculate the lactation-specific prevalence by hand or using our spreadsheet. The simple average of these lactation-specific numbers (BLV herd profile average) is a good “single number” estimate of your overall herd prevalence (33)(Figure 1).

Which 40 Cows to Test?

For each lactation group (1st, 2nd, 3rd, and 4th+) select the 10 most recently calved, or fresh, cows that are greater than 3 days in milk. Cows less than 3 days in milk should be skipped as test accuracy is poor that early in lactation.

Use the above guidelines and don’t be tempted to purposefully select certain cows that you would like to test. This sort of “cherry picking” would lead to the sample results not being a good representation of your herd’s true BLV status.

How can the BLV herd profile be used?

Your herd’s BLV profile can be used to monitor the BLV status of your herd. The average can be used as an estimate of the overall herd prevalence of BLV without having to test your entire herd.

You can use a BLV herd profile to compare your herd to other herds. With our herd profile spreadsheet, you can compare your herd to the herds in our 2014-2016 national study of BLV.

You can also use a BLV herd profile to monitor changes in your herd’s BLV status over time. For example, if you made a management change to decrease BLV in your herd, you could use annual profiles to monitor your progress.