The hypostatic genotype of the recessive white prat breed of chickens

The genetics of the plumage color of the White Prat breed of chicken was studied. Results of crosses between the White Prat breed and Recessive Wheaten (ey/ey) tester line, and Buff Prat (eWh/eWh Co/Co) or Castellana (E/E) breeds, suggested that the former carries the buttercup allele (ebc) at the E-locus, the columbian restriction gene (Co), and the autosomal recessive white (c) gene. Heterozygous Co/co+ in the presence of ebc resulted in a modified stripe pattern in the chick down. The ground color was very dark tan, whereas the light back stripes and the broken head stripe were similar to those of buttercup chicks. Adults were typical buff columbian with considerable black markings on the feathers. The homozygous ebc/ebc Co/Co produced chicks with a black back and a brown head, similar to those previously described for the interaction between Co and the brown (eb) allele. The presence of the recessive white gene masked unexpected genetic variation at the E-locus in the Prat breed, the Buff variety carrying the dominant wheaten (eWh) instead of the buttercup allele. The sex-linked gold (s+) allele was the most frequent in the White Prat variety. The silver (S), sex-linked barring (B), blue (Bl), and possibly dominant white (I) alleles also were present at low frequencies.