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Already more than hundred years ago Dr. Reginald Punnett, a professor at Cambridge university hypothesized that the gene for barred color patterns acted differently in male and female chicks. The males received two barred genes and the females only one, so male chicks would be lighter in color and more barred than the females. He experimented and found that by crossing brown colored males with barred silver females (he favored the Plymouth Rock to supply the barring gene), the effect was accentuated, and chicks could be easily visually sexed by their color and down patterns on the day they hatched. Females tended to have clearly defined “chipmunk stripes” on their backs and males tended to have a silver sheen on their down with a light spot on the backs of their heads.
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