Bash
A cow milks after giving birth. She will essentially continue to produce milk for as long as she is being milked. The longer she is milked the less milk she will have per day. The ideal cow gives birth once every 365ish days and will milk for 260 days a year, then spend between 45 to 90 days as a ‘dry’ cow–i.e. one that is not milked and therefore will quit producing milk. Farmers ‘dry-off’ a cow so she has a chance to recover from ‘effort’ of producing milk. A cow produces the most milk during her third lactation with good cows milking 100 lbs a day and the highest cows making in excess of 150 lbs a day. A good dairy herd will make 80 lbs of milk per day a cow or 30,000 lbs a year. Whole milk weighs 8.4lbs/gallon, so you can do the math. Your average farmer must milk all his cows every 12 hours 365 days a year because at any time greater than 3/4 of the cows in a well kept herd will be ‘in milk.’ Many farms are going to milking cows three, four, five, or even six times a day. This is a huge amount of labor, but it seems that cows might be happier being milked that amount of time–remember if her calf were milking her the calf would be milking her constatly.