There is now way to know if she has the Silver genes unless you breed her, unless it is from a breed that is know to always have the silver genes like anything with silver in its name ( Silver laced, Silver Penciled ) or Light Columbian colored hens. ( Sussex. Brahmas, Wyandottes)
It is actually not a matter of "dominant white" gene, versus the "silver gene." It is a matter of the presents or the lack of the silver gene. A dominant white hen can produce sexlinks if she has the silver gene. Like RIW carry dom white and have the silve gene, so the produce sexlinks with the females being red with WHITE tails. White leghorn hens, which are dominant white but usually do not have the silver gene, produce chicks that are all white with black dots.
The names of all these Sexlink breeds get confusing becuase when I think of a golden commet, I think of Red hens with white tails, The white tails comes from the dominant white in the RIW hens that should be used to creat them. Since White Rocks are generally Recessive white, not dominant, if she did have the silver genes, the pullets she would produce would be red with BLACK tails, much like RIR and Pro Reds. The Sexlinks with that are red with black tails are what I call Red Sexlinks. Also with White Rocks being recessive white, the could be masking other colors like Black or Barring and you may end up with just mutt colored chicks if they are.
So if you want Sexlinks with the females being red with white tails, you should use RIW hens with a gold rooster of what ever breed you choose. That is what I use and I get cute little red and white pullets and white roos.
