Why do sex links lay more eggs?

[sfisher]

How come sex links lay appox. 300 eggs a year. And the chickens they come from only lay at the most 260 a year?

 

[Corey NC]

It's the genetics, they are specially planed out breeding programs to get the hens to lay loads of eggs.

 

[greyfields]

Imagine a family tree that instead of branching-out, converged to a single point. This is how breeds of livestock are created. A vast portion of the original genes and DNA is vacant in purebreds, because they were initially inberd and you are starting with only a narrow band of deviation left.

Now imagine a second breed which was created the same way, but who's genes were selected for different appearance that the first example. When crossing these two birds, you get what is called heterosis, or hybrid vigor. The offspring suddenly have genes and DNA in them that doesn't exist in the parent stock. Because of this, your hybrid chickens are always more vigorous and perform better than any single purebred of any type.

Now, if you were to go and breed a crossbreed/hybrid, you have opened pandora's box. You will get 100 different chicks from 100 different eggs because the possible outcomes go up exponentially.

This is probably why we still have purebreds around, since you can cross breed them with predictable outcomes. Whereas if all hens were grade animals (meaning not purebred), you would never have a reliable result with the same crossbreeding twice.

The above poster did mention something that is somewhat true. The parent stock for making hybrids are selected for certain characteristics and can be selectively bred to certain ends (but not outcrossed too much, or you lose the essential 'breed'). However, the biggest thing is the simple meeting of the DNA to create the hybrid, as much as it is selective breeding of the parent stock.

Finally, my recommendation. Get yourself a RIR rooster and a few Barred Rock hens and make your own Black Sex Link pullets. It's great fun. Everyone should do this once in their life!