Are you asking about how many days it will take the cow to come into heat after calving, or how many days is it between heat periods? For the former, it's 45 to 80 days. For the latter, it's ~21 days.
A cow cycles every 21 days. The estrus period, or heat period, in the cow only lasts for 24 hours, so it is in this time period that she can conceive. If she misses, then she will be caught again in her next heat. Cows with great fertility often catch on the first heat when put out with the bull.
From the time that the initial signs of labour begin for a cow, the amount of time it takes for a cow to start this labour process to when the calf hits the ground is mainly measured in hours, not days. How long it takes for a cow to give birth really depends on her body condition, her experience, how big the calf is inside her, environmental conditions, and whether the calf is presenting normally or not.
As a result there really is no set-in-stone time it takes for a cow to give birth. For experienced cows, it's only a matter of 5 to 6 hours until the calf arrives. For a heifer, it can be a few to a number of hours longer.
See the related question below for a similar answer.
If, by any chance, you are asking how long a cow is pregnant in days, the average is around 285 days long. Please see the related question on the length of gestation below for a more detailed answer.
A cow will come into heat once every 17 to 24 days (average is ~21 days), depending on age, breed, and body condition.
The cow has the longest gestation period of the two species: A dog is pregnant for around 60 days, whereas a cow is pregnant for around 285 days.
Around the same length of time as a domestic cow: around 10 months.
Valbazin cannot be used on pregnant cows that are in their first 45 days of pregnancy, nor can it be used on breeding dairy females. If you have pregnant cows that are at least 45 days pregnant, yes, you can use it on your pregnant cows.
A heavily pregnant cow, or a long-bred cow. Or, a cow that is expecting soon.
A cow is pregnant, or 'in calf', for approximatly 40 weeks (9 months).
Only once.
A pregnant cow who gives birth is a mother.
No, the cow will not go into estrus after she becomes pregnant.
Talk to your cow. If she is pregnant your character will mention how see and her baby is doing. If your character does not mention a baby then your cow is not pregnant.
Bred cow.
2 days
human sperm cannot get a cow pregnant. The only species humans can get pregnant with their sperm is another human.