When are the cows due to calve?


Wednesday 1st February Meet the cows.

These are the cows we will be following until they calve in a few weeks time. At the moment they are still out in a field – but is this where they will have their calves?

Meet the cows

Can you help the farmer work out when our cows are due to calve?

These cows where mated with the bull back in May 2011. The farmer does not record the mating of each cow. He just puts the bull in the field and leaves him there for a short time and lets nature take its course. To work out when the cows are likely to start calving he just records the date he put the bull in the field. The gestation period (how long an animal is pregnant for) for a cow is 270 or around 9 months; just like a human.


The bull was put in the field with these cows on the 20th May 2011 can your class help the farmer by working out when the first cow could calve. This date is only a guide, as we said the farmer did not watch or record individual matings so the first cow may not have mated on this date. But using this as a guide allows the farmer to start planning for calving. Just what this entails we will look at next time.

Can you work out when 270 days from 20th May 2011 is using a calender?

Or you produce a spreadsheet which calculates the date a cow will calve based on the day it was mated?

Use these headings. Then put a formula in cell B6 which adds the cows gestation (270) days to the date mated (20 may 2011). You might need to format the cell A6 and B6 for date.

Can you add the same information for other animals?

  • A sows gestation is 114 days,
  • a Ewe’s is 147 days

You can download a completed Gestation Calculation Sheet here – Gestation Calculation Sheet