Dairy farms are to produce milk, which is then turned into cheeses, milk, butter and other dairy products.
To do this, the cows must remain pregnant. In the case of dairy cattle, the bulls are really nasty, (Guernsey, Holsteins, etc. The Hereford breed is rather nice to deal with. A beef breed. However, the Angus black in color are again, really nasty...) Dairy bulls, again are difficult to deal with so most dairy farmers don't have one. What they do is call a guy who has frozen sperm, collected from the top bulls on the continent.... and after the last calf is born, on the heat cycle (approx 9 days after the birth of the last calf ) she is again ovulating, and again fertile, and is re-impregnated.
That calf is moved to an area to be "nursed" by machinery, until it is "weaned" . If it is male, it may be sold to be veal. If it is female, it may join the farmer's herd. The farmer chooses sperm from bulls that produce cows with very high milk production.
So many of the calves, male or female are incidents.... Many dairy farms will literally pull a birthing calf out of the female with chains and wenches when she goes down to deliver. When she lays down to birth, if she is having difficulty, this is the usual method. The end product is not a calf, but dairy products.