You can test the amount of color a Marans male brings in by crossing him to a white egg layer. Then, hatch some pullets. When they grow out and lay eggs, you will know that rooster's actual contribution. This test has used in France to weed out the light egg genetics from the dark genetics, saving generations of time wasted with Marans males who carry the light egg genetics.
Thanks for that. I have 2, 6 week Olds who's mothers were SLW and my marans the father. I also have one who just hatched who's mother is a silkie. They may not be white egg layers per se but they lay very light colored. Hopefully at least one of them is a pullet so I can see how much color he brings.