The cow gestation is calculated using the following formula:
\[ \text{Calving start} = \text{Day when exposed to bull} + 283 \text{ days} \]
Remember that the healthy gestation period may range from 279 to 287 days.
The end of the postpartum interval period is calculated as follows:
\[ \text{End of interval period} = \text{Calving} + 55 \text{ days} \]
For cows pregnant with their first calf:
\[ \text{End of interval period} = \text{Calving} + 65 \text{ days} \]