The Holstein cow is your traditional milk producing cattle stock animal, at least in Europe and North America. A Holstein is easily identified by its distinctive pattern of black and white fur, however they come in a red-white variety as well.
Originally, imported from europe, the current incarnation of Holstein cattle is the result of a century and a half of controlled breeding. The animal gets its monkier from the title of the Holstein-Friesian organization, the body formed to maintain the standards which define the breed.
At birth, the average calf weighs around 90 lbs. A full grown cow can weigh in the neighborhood of 1,400 lbs or more, and bulls around 2,700 lbs. At the age of two, a heiffer, a non lactating 'virgin' bovine animal, is impregnanted and made into a cow, which after giving birth to its first calf can produce anywhere from 20 to 60, or more lbs of milk per milking, and most cows are milked twice daily. Some cows have been reported to produce up to 67,000 lbs of milk per year on a twice daily schedule.
Dairy cows can usually produce milk for three or more years, making their productive life expectancy some where around four to five years (after which they are promptly sold for slaughter...ground beef in most cases)
Fun Holstein Facts!
-Most pregnancies are invoked through artificial insemination
-Average gestation period for a Holstein is about nine months (same as humans and sheep)
Most facts pulled from Holstein Association USA, http://www.holstien.com