Dairy cows may be discovered both in herds or dairy farms where dairy farmers own, manipulate, care for, and accumulate milk from them, or on business farms. Herd sizes vary around the world depending on landholding way of life and social structure. the united states has an predicted 9 million cows in round 75,000 dairy herds, with a median herd length of 120 cows. The wide variety of small herds is falling unexpectedly with the 3,100 herds with over 500 cows producing fifty one% of U.S. milk in 2007. the United Kingdom dairy herd ordinary has almost 1.five million cows, with approximately 100 head stated on a mean farm.In New Zealand, the common herd has greater than 375 cows, whilst in Australia, there are approximately 220 cows within the average herd. To hold lactation, a dairy cow ought to be bred and convey calves.[relying on market situations, the cow can be bred with a "dairy bull" or a "red meat bull." lady calves (heifers) with dairy breeding can be stored as replacement cows for the dairy herd. If a alternative cow turns out to be a substandard producer of milk, she then is going to market and may be slaughtered for pork. Male calves can both be used later as a breeding bull or sold and used for veal or red meat. Dairy farmers normally start breeding or artificially inseminating heifers round thirteen months of age.A cow's gestation period is about nine months. New-born calves are separated from their mothers fast, generally inside three days, because the mom/calf bond intensifies through the years and delayed separation can reason extreme strain on each cow and calf