Page 21 - Turkey Book from Meathead

As with chicken, modern American turkeys have been bred to have large breast lobes because most Americans prefer white meat. They have also been bred to grow quickly. According to Penn State University, females (hens) will go from hatching (a poult) to 14 to 20 pounds (live weight) in 12 to 14 weeks. Males (toms) can reach 35 to 42 pounds in 16 to 19 weeks. An immature male is a jake, an immature female is a jenny. Some people believe hens are slightly more tender than toms, but because most turkeys are slaughtered when young, there is no noticeable dierence according to taste tests
by Cook's Illustrated magazine.