I have read that Dark Cornish in Australia are based on Wheaten (gene at the e-locus), so they hatch out yellow but grow up to look the same as the Dark Cornish in other countries (the Dark Cornish I've seen in the USA have chipmunk-striped down, probably based on e+ at the e-locus).
I see two single combs in the mix:
a yellow chick on the bottom right facing the camera
a red chick on the left, midway between top and bottom, also facing the camera
Those chicks have two single comb parents, so not a Dark Cornish mix.
At that age, I feel that single combs usually look...
There are about four ways (genetically speaking) to make a white chicken, and only one of them will work for making sexlinks.
To make sexlinks, you need the Silver gene (turns red/gold into white.) If you want to be sure of having that gene, you can use something like Delawares or Columbian...
:thumbsup
You may want to keep records on how big they are at each age. Any chicks will tend to grow faster at first, and slow down as they get older, so you might find that you do want to butcher them at a young age (fast growth, tender) rather than continuing to raise them to a bigger size...
I would probably just keep a pure flock of Dark Cornish, and a separate pure flock of White Rocks. Then you could cross them each year to produce your meat chicks. Since White Rocks are usually better layers than Dark Cornish, I would use White Rocks as the mothers and Dark Cornish as the...