This article is courtesy of the Beef Cattle Research Council, and was first published on the BCRC blog, here.
Did you know that heifers take longer to start cycling after having their first calf than mature cows do? It means lining up the calving season for a cow’s second calving requires that heifers be bred to calve first in the season.
“It’s just basic biological math,” says Dr. John Campbell, veterinarian, and Professor in the Department of Large Animal Clinical Sciences at the Western College of Veterinary Medicine. He points out that this is why a lot of what would-be second calvers drop out of the herd – they simply don’t have enough time to start cycling and rebreed.
To calve at the same time the following year, cows and heifers need to be bred about three months after a calf is born. This is easier in cows as they return to estrus 50-60 days after calving, giving them plenty of time to get bred in the first cycle after bulls are turned out. It is more challenging for heifers because they take 80-100 days to return to estrus meaning they may not have even started cycling again prior to bull turn out.
Breeding heifers prior to cows does lengthen the overall calving season, but Campbell points out that this can have advantages. Heifers are more likely to have problems calving and, with less animals calving during the same time period, producers have more time to closely monitor and deal with any potential issues. Heifers are able to calve on bedding areas when they are fresh and at their cleanest.
While some producers may not like the idea of extending the calving season, Campbell notes that if you aren’t intentional about doing it at the beginning those heifers start to fall behind and, eventually, you are either culling hard or extending the calving season at the end to wait for the stragglers to calve.