To fill a gallon pail with milk, the milker (or automatic milking machine) must collect approximately 350 squirts of milk from a cow's udders. Most dairy cows can produce up to 6.5 gallons of milk per day. This averages to about 350,000 standard eight-ounce glasses of milk produced by a typical dairy cow in a year's time. America's dairy industry produces an average of 21 billion gallons of milk each year. Source: Ansc.Purdue.edu