A New Way to Think About Voluntary Waiting Periods

By: Devan Fielding
Dairy Specialist
Grand Valley Fortifiers

There has always been a great debate on the voluntary waiting period (VWP). Is it too long, too short, or just right? Voluntary waiting periods are different for every farm—you can even get more specific and have a different number of days for each cow.

A few questions to consider when establishing a voluntary waiting period are: What is my average conception rate? How hard are my cows milking? And how does my stated voluntary waiting period align with the actual timing of our first service? Producers often claim that their voluntary waiting period is 60 days in milk (DIM), yet in reality, the first service typically occurs around 80 DIM. This means that cows are likely being bred between 60-100 days in milk, which is a wide and inconsistent range. We need to think about shortening this range to optimize breeding. This can be done through programs like double Ovsynch or by ensuring cows are cycling by 60 DIM. If cows are cycling by 60 days and our voluntary waiting period is 60 DIM, almost all cows should be bred by 81-85 DIM, making the actual days in milk at first breeding 72.5 days. A good rule of thumb to establish a proper voluntary waiting period for your herd is:

Voluntary Waiting Period (days) = Average Conception Rate (%) + Average Liters of Milk per Day.

Table 1. Voluntary Waiting Period based on conception rate and average production.

In Table 1, you will find examples of proper voluntary waiting periods based on your conception rate and average milk per cow per day. You will notice that lower-producing herds with low conception rate need to start breeding cows as soon as 40 days in milk. So why does average conception matter? With a 20% conception rate, it will take an average of 5 services for a cow to conceive. If you have a 30-liter herd average and a 20% conception rate, this means that she will be a maximum of 155 days in milk before catching (if bred every 21 days). She will then need to milk for another 223 days before drying off, totaling 378 days in milk. If she is only peaking at 40 liters, by the time she is 378 DIM, her production will likely drop below 20 liters. On the opposite end, we don’t want high-conception, high-milking herds to breed before 100 days, as they will get dried off too early when they are still milking well.

Why is average liters important to the equation? Cows with higher milk production may not be able to conceive as easily at their peak milk production. This is because they are already in negative energy balance due to not being able to eat enough to sustain their high milk production. These cows will need extra time to come back to a normal feed intake so they can consume enough nutrients to maintain production while supporting reproduction.

While there may be lots of other opinions on the voluntary waiting period, these benchmarks have proven successful in my previous role as a Reproductive Management Specialist for Major Dairy AI Services. Using this benchmarking, I was able to manage dozens of barns achieving an average pregnancy rate of 35%. In conclusion, a voluntary waiting period isn’t one-size-fits-all and should be adapted to your specific operation, with your conception rate and production level driving your breeding timing.

This article was written for the Summer 2025 Dairy Grist. To read the whole Dairy Grist, click the button below.

Click here to read the whole Grist!

This article was also written for the Summer 2025 Western Dairy Grist. To read the whole Western Dairy Grist, click the button below.

Click here to read the whole Western Grist!