Abstract
1. A study of primary wing feather development rate in guinea fowl revealed genetic control through a single pair of sex‐linked alleles. The allele for slow feathering (K) was dominant over that for rapid feathering (k+)..
2. Wing feather sexing showed 94% accuracy in 10‐d‐old keets.
3. Incidence of rapid feathering allele (k+ ) was higher in the population selected for high body weight compared to the unselected population.