Probably 15-20 generations. The early years working with just this pullet, her parent stock, and resulting crosses,I worked on type,comb,leg feathers,and color.Vulture hocks and clean lacing were early obstacles.The Cornish blood was show stock(short legged bowling balls),I had a hard time getting any height. About 8 years ago I introduced a light Brahma male, which improved size,and type, but totally blew up the color for a while, and then again 4 years ago.