You can determine a cow's due date with information about the cow's gestation period, date of inception and breed information. The gestation period refers to the length of the pregnancy from inception to the calf's birth. Knowing the due date of your calf can help you plan ahead and make your cow as comfortable as possible leading up to the date. It also gives you a chance to prepare in case you cow or calf needs any kind of help during the birth.
Determine the insemination date. First determine the date that the egg is actually fertilised. This marks the start of the gestation period and from that you can begin to count down the days until the calf's birth according to the length of time determined by the cow's typical gestation period. This is an easy task as you can only inseminate cows within 24 hours of them in heat. The optimal time for insemination occurs six to ten hours before the end of those 24 hours before the egg dies.
Check the calf gestation table. The gestation table is a table that lists the average due date of a calf according to the date of insemination. Every day of the year is listed as a possible insemination date in the table as well as the corresponding due date of the calf. The average length of gestation is nine months, or 283 days, but the date can vary by as much as three weeks according to other variables such as breed or the environment. You can also use an online calving date calculator to complete this step.
Consider your cow's breed. Different breeds of cows have different gestation periods that can fluctuate with the average due dates listed on the gestation table. For example, the Brown Swiss Cow has a longer than average gestation period and breeds larger calves as a result.
A longer gestation period leads to a bigger calf, which can cause problems during the delivery. While you cannot help it with certain breeds, it is something to keep in mind and possibly plan for if your cow ends of having a longer than average gestation period.