what I know about chickens

Class of chickens as classified by the American Standard of Perfection. They have been genetically selected for high egg productivity, but usually have small bodies that make them undesirable as meat producers. The small bodies benefit these breeds because very few nutrients are wasted for producing great body mass. Instead, they direct more of their dietary nutrients into the egg production. The egg producing breeds are further divided into birds that produce white shelled eggs or brown shelled eggs. The best white shell egg breeds are descended from the Leghorn breed with several different feather color patterns to select from. The best brown shell egg production breeds are developed from Rhode Island Red stock. Regardless of which shell color breed selected, there are many modern varieties from which to choose.

The meat-type breeds of chickens are not really breeds at all. Instead, they are hybrid varieties or combinations of many different breeds. The combinations of breeds are selected to produce a variety (strain) with meat characteristics that the producer desires most. Some breeds grow faster and larger while others emphasis traits like larger breast meat yield, more efficient feed conversion, or more disease resistance. The strains are named after the breeding companies that genetically develop them, like Arbor Acres, Ross, Peterson and Hubbard, to name a few. The weakness of these varieties is that they do not lay as many eggs per hen as the egg laying breeds discussed above. These strains are used by broiler producing companies that commercially produce broilers sold in supermarkets.

The third type of chicken breeds are those that are dual purpose. They are not as good in producing eggs as the Leghorn or Rhode Island Red breeds, but they have much better meatiness. They are also inferior in meat production characteristics as compared to the commercial meat-type hybrid varieties, but they are much better egg producers. Typical breeds in this dual purpose category are New Hampshires, Plymouth Rocks, and Wyandottes
Sex link chickens , Hatcheries have developed chickens that can be sexed at hatch by color. This is a cost effect measure because the art of sexing chickens has to be learned and was first developed by the Japanese.
Crossing a legorn hen with a rode Island red rooster will produce red pullets and white rooster and sexing can be done at the hatchery.
crossing Barred Rock with Rhode Island reds produce black baby chickens some with a white spot on the top of the head. The chick with the spot is female.