Preparing for calving
As the estimated date nears, move the cow to a clean, sheltered calving area and check on her regularly. Have supplies ready, including clean towels, iodine for the navel, calving chains or straps and your vet's number. Watch for udder filling, relaxation and swelling around the tailhead and vulva, and separation from the herd, which often signal that calving is close.
Why a window, not a single day
Gestation length is an average, not a guarantee. Because individual cows, breeds and calf sex all vary, the calculator shows a window of a few days on either side of the estimate. Use the estimated date to plan herd management and labor, but be prepared about a week ahead in case she calves early.