A newborn calf weighs from 80 to 100 lbs. at birth. The newborn is fed colostrum milk for the first three days. Colostrum is a special milk that gives the calf extra nutrients to help get the calf off to a healthy start. Calves are then fed milk or milk replacer starting at day three. They are also fed calf starter, a grain, beginning at 7 to 10 days of age. They are 4 to 8 weeks old when they are weaned from milk.
A six month old heifer begins eating silage, hay, and grain. The heifers may also be exposed to pasture where they can eat grass. The heifers weigh about 400 lbs. The farmers want their heifers to gain 1.6 to 1.8 lbs. a day.
The heifer is called a yearling because she is over one year of age. She weighs about 700 lbs. and still has more growing to do before she can begin milking. She will be bread soon because it is ideal for her to have a calf and begin milking at the age of two. The gestation period for a heifer is 283 days.
Two year olds are also known as "first-calf heifers". After the heifer has her calf, she is not referred to as a cow. She is now producing milk and being milked two to three times a day. She will keep growing for the next few years before she is fully mature. She weighs about 1,200 lbs.
The adult cow weighs over 1,500 lbs. At the age of 5 the cow has had four calves. She eats over 100 lbs. of feed a day and can produce over 12 gallons of milk during her early part of lactation. A mature cow produces about 25% more milk than her first heifer. She is milked until the age of 7.