Enter the date the cow was bred. You get the expected calving date and the three dates that actually drive the work between now and then.
Expected calving is the service date plus the gestation length. Dairy cattle average 279 to 283 days, and the calculator starts from a breed figure you can overwrite: Holstein and Jersey 279, Ayrshire 279, Guernsey 284, Brown Swiss 290. A beef sire on a dairy cow usually adds one to three days.
Pregnancy check is set at 32 days after service, which suits ultrasound. If your vet palpates instead, 35 to 45 days is the usual window — and checking early is what stops an empty cow drifting for another cycle.
Dry off is 60 days before the expected calving. That is the standard target: the udder needs the rest to repair tissue for the next lactation, and shorter dry periods cost milk in the lactation that follows.
Close-up is 21 days before calving, when the cow moves to the transition ration so her rumen is ready for the milking diet and the risk of milk fever and ketosis drops.
Each one is money. A dry period that starts late steals udder rest; one that starts early wastes feed on a cow that could still be milking. A missed pregnancy check leaves an open cow undetected for another 21-day cycle, and every extra open day costs feed without milk to pay for it. These are small dates with large consequences, which is exactly why they are easy to lose on a wall calendar.
About 279 to 283 days — roughly nine months and one week. Holstein and Jersey average 279 days, Brown Swiss run notably longer at about 290. Individual cows vary by around a week either side, so treat any calculated date as the middle of a window rather than a promise.
A little. A beef sire on a dairy dam tends to add one to three days, and bull calves are carried marginally longer than heifer calves. Neither is enough to change how you manage the cow, but it is one reason a calving comes a few days later than the calculator says.
Use the pregnancy-check result instead: your vet or technician estimates the stage of pregnancy in days or weeks, and counting back from that gives a service date good enough to plan dry-off. If you never recorded the service, the check itself becomes the only reliable anchor you have — which is the argument for recording every service as it happens.
DocDairy works these dates out for every cow the moment you record a service, and puts the ones due today on one printable list. Ten languages, offline in the barn.
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