On average, the gestation period or length-of-pregnancy of a cow is 285 days long. This is similar to the pregnancy period of a woman, which is closer to around 9 months or ~260 days.
However, actual gestation period of a cow can range from 270 days to 295 days, depending primarily on breed[s], age, body condition and nutritional health. Gestation period is also controlled by genetics, but not rate of maturity. The rate of maturity is more to do with the age a bovine reaches when it starts to put fat down, not muscle, and has very little to nothing to do with reproductive characteristics including length of gestation.
Here are some rules of thumb to remember when trying to figure out how long your cows or heifers will be pregnant for:
Please see the related questions below for various breeds and their consequential length of gestation.
a brown Swiss cow or heifer has the same gestation as any beef or dairy bovine which is 283 to 285 days or 9 months
It would be about the same as with a Jersey cow. See the related question below.
Not really. On average they are similar (around 285 days) but NEVER the EXACT same. For instance, a Jersey cow will have a shorter gestation period than a Charolais cow, and a thin Angus heifer will have a longer pregnancy than a normally-conditioned cow of the same breed. How long a cow's gestation period depends on breeding, health, conformation and age. See the related question below for more information on this.
The gestation period of a miniature cow is ~284 days.
For a tiger, the gestation period averages around 100 days. For a cow, the gestation period averages around 285 days.
The gestation period of a Guernsey cow can be expected to be around 275 to 285 days long.
The gestation period of a Gelbvieh cow averages around 260 to 280 days long.
A heifer is a female bovine that has not yet had its first calf. A long bred heifer is a heifer well along in the gestation period and due to calve shortly.
The gestation period of a mini cow is around 285 days, which is the same length for a full-sized cow.
The gestation period of a Holstein cow averages around 283 to 286 days.
The gestation for a cow that's been AI'd would have the same gestation period as a cow that has been naturally bred: around 285 days, plus or minus. Artificial Insemination does NOT affect the length of gestation of a cow, it only affects what her offspring is going to be.
The gestation length of a Dexter cow is short, which is around 260 to 283 days long.