The production of recombinant proteins in the eggs of transgenic chickens offers some advantages. A chicken's generation time is around 6 months. That's far shorter than the generation time of a large mammal, such as a goat, which requires 18 months to grow from engineered embryo to milk-yielding adult. Chickens also produce lots of protein. Each of the approximately 330 eggs a hen lays annually contains 6.5 grams of various proteins. An additional advantage of producing pharmaceuticals in eggs is that egg white is far less complex biochemically than milk is, and there are established methods for easily extracting various proteins from eggs.