Lavender is recessive and brown is dominant, which makes this more complicated. Is. bred to brown produces all birds that look just like any other brown leghorn but have the hidden gene for lavender. So Brown split to lavender. if you breed splits to splits you get 25% lavender, 50% splits (that...
Thats how they started with the Isabella leghorns (but with Lavender Orps). I don't know if the heartiness issues came from the lavender coloring or the orps they used.
Between chickens, guineas, and my pigs I order a ton of feed every 2-3 months. The pigs only get about 200-250lbs of the ton though (I love American Guinea Hogs, I feed them mostly on kitchen scraps).
Aren't a lot of people having trouble with the Isabella's that are commercially available out there? I thought I heard something about a terminal gene.