How to track gestation length with DairyComp

Gestation length is an important consideration when setting dairy protocols, including when to move prefresh animals and when to dry cows off for an optimum dry period length. Successfully monitoring and analyzing your herd’s gestation length can have a significant impact on pen management and each cow’s production later in life.

Below, we’ll walk you through how to use DairyComp to determine average gestation length by lactation group and how that may apply to management protocols.

Because gestation length can vary from farm to farm, use the item ‘Previous Days Carried Calf’ to determine gestation lengths – further down we’ll discuss why this is so important. But first, let’s gain insight into the herd by using the following commands:


This command averages gestation length for cows +/- 20 days from a “normal” gestation length of 280 days, broken out by lactation group.


Substitute N for the lactation number you’d like to view. This command gives us a graph to determine the normal gestation length distribution for the farm.

The below set of examples demonstrates how gestation length can vary by farm. Not only does the gestation length vary on farm A by a full week from first lactation to third and greater lactation cows, the gestation length for first lactation animals differs four days from farm A to farm B. The GRAPH command shows that the distribution supports the average values from the SUM command for lactation=1 animals on each farm. Creating a generalized protocol for moving prefresh heifers would not apply farm to farm which is why it’s important to utilize the farm’s actual averages to create protocols.

Farm A

Farm B

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