Over the years, traditional
breeds have lost their commercial importance and crossbreeds and
hybrid strains have been developed into the modern chicken.
In the modern egg industry, the birds are hybrid White Leghorns
hybrids that resemble New Hampshire Reds and Barred Plymouth Rocks.
Today's egg producing hens can lay over 300 eggs per year; this
is over twice the average of 150 eggs per year in 1947.
broiler industry has developed a hybrid that is unlike any other
breed. Today's broiler can achieve a 4-pound live weight in six
weeks. Twenty years ago, it took 14 weeks to achieve a 5-pound
live weight. These advances are the result of scientific progress
in genetic, nutritional, and environmental research.
turkey industry has developed a hybrid white turkey that is larger
and faster growing than purebred or wild turkeys. Modern turkeys
are so large they can no longer breed naturally. All modern turkeys
are artificially inseminated. Artificial insemination allows selective
breeding so that breeders can raise fewer males and achieve higher
rates of hatchability.