In order to rationally arrange production, properly raise and manage pregnant cows at different stages, so as to make pre-natal preparations, it is necessary to calculate the expected delivery date of the cows.

Calculation method: Generally, the gestation period of a cow is 280 days, and the method of "minus 3 plus 6" can be used, that is, the calving month is the mating month minus 3, and the calving date is the mating date plus 6.

For example: the last time a cow was bred was July 15, 2017, and the expected date of the cow this time was April 21, 2018. The final mating date of the other cow is January 29, 2017, and the expected date of this cow is November 4, 2017. Month: 1 + 12-3 = October, date: 29 + 6 = 35 (October is 31 days is November 4).

In production practice, in order to reduce cumbersome calculations, the expected date of the cow is often formulated as a cow pregnancy calendar. According to the mating date, the expected date of the cow can be checked.