How are chicken breeds made larger over time?

[Bryce Thomas]

I swear I have seen a thread on this site called the giant silkie project or something and it showed this really big silkie rooster but it was the size of like a sumatra or a jersey giant, do you just cross the breed with a jersey giant then breed with the original breed to get the normal coloring then your left with a chicken thats really big? Im curious, please explain.

 

[1muttsfan]

The fastest way to get major changes in things like color, size and type it to outcross to another breed/color. However, the weeding out process to get back to the proper breed traits can be very complicated, involving several generations and often inbreeding and line breeding to fix the desired traits and to find and eliminate undesirable traits, especially recessive ones. You also have to breed quite a large number of birds if you are doing it right, as the culling is quite rigorous.

 

[JacinLarkwell]

I swear I have seen a thread on this site called the giant silkie project or something and it showed this really big silkie rooster but it was the size of like a sumatra or a jersey giant, do you just cross the breed with a jersey giant then breed with the original breed to get the normal coloring then your left with a chicken thats really big? Im curious, please explain.

Takes multiple generations and hard culling. @MysteryChicken is the one working on that project