Just do it: Grab a pen and paper to calculate the percentage of cows calving in the first 21 days of the calving season. This is a very important number to record and think about as one develops management plans and reviews those plans.
Why? The upcoming breeding season is not very far away. For those who have an early calving season, the bulls already may be out with the cows.
Are you at 60 percent? As each operation reviews its herd calving history, a cow is expected to start cycling following birth and prior to the bull arriving in the pasture. Ideally, a cow should cycle within 80 days of calving and then settle with next year’s calf. Therefore, the cow is expected to maintain an average calving interval of 365 days.
How many cows maintain a 365-day calving interval? Well, that particular number is not well tracked in the beef business. Instead, producers can and should calculate the percent of cows in the herd that calve within the first 21 days of the calving season and each successive 21-day period thereafter.
Many producers have been calving for the last three weeks, so stop reading this article and go pick up the calving book. Now count how many cows calved during the first 21 days of the calving season. Once you know that number, divide it by the number of cows that are expected to calve. The answer is the point of this discussion. What did you get?
Let me say it again: Go get your calving book, count the number of cows that calved during the first three weeks of the calving season, and divide it by the number of cows expected to calve.
Typically, that number should be more than 60 percent. This does not mean a particular cow has a 365-day calving interval, but it is a good indicator that the cows are getting bred on time.
A producer should be questioning why all the cows don’t calve during the first 21 days of the calving season. About 40 percent of the herd calves during the second 21 days or later. Why? Once a cow misses an opportunity to breed, the chances of getting back into the first 21 days are low.
Those cows would need to be cycling 60 days post-calving or sooner following calving to move up into the first 21 days. That does not happen routinely because cows seem to need 60 to 80 days post-calving to rebreed.
In fact, if the percentage of cows calving the first 21 days of the calving season is less than 60 percent and the percentage of cows calving the second 21 days of the calving season is greater than 25 percent, a serious re-evaluation of the herd needs to occur. It means that more cows are slipping back and not rebreeding on time. In other words, the cows are not maintaining a 365-day calving interval.