Commercial egg producers use proprietary breeds of chicken developed specifically for egg production. The chickens that provided the foundation for these proprietary breeds may have been selected because of properties of the eggs they produce, such as color or size. All of the proprietary breeds have similar beginnings from certain types or breeds of chickens.
Most of the white eggs sold by grocery stores are produced by Leghorn chickens or by proprietary breeds that Leghorns were used to create. Leghorns are lightweight birds that start laying eggs as early as 4 to 5 months of age. They can produce nearly 300 eggs per year without going broody. Leghorn chickens use most of the nutrients they consume to produce eggs instead of meat and have excellent feed-to-egg conversion even among layers.
The Rhode Island Red is the progenitor of the most efficient commercial brown egg producers. Unlike the Leghorn, the Rhode Island Red is a dual-purpose bird, which means that some of the nutrients they consume produce meat. The Red Star and Black Star hybrids are two production egg-layers created by crossing a Rhode Island Red rooster with a hen of a different breed. The New Hampshire Red, itself a descendent of the Rhode Island Red, is crossed with a White Plymouth Rock to produce the Golden Comet, a hybrid that produces many of the large brown eggs found in grocery stores.
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