THE HYPOSTATIC GENOTYPE OF THE RECESSIVE WHITE PRAT BREED OF CHICKENS

The genetics of the plumage color of the White Prat breed of chicken w as studied. Results of crosses between the White Prat breed and Recess ive Wheaten (ey/ey) tester line, and Buff Prat (e(Wh)/e(Wh) Co/Co) or Castellana (E/E) breeds, suggested that the former carries the butterc up allele (e(bc)) at the E-locus, the columbian restriction gene (Co), and the autosomal recessive white (c) gene. Heterozygous Co/co(+) in the presence of e(bc) resulted in a modified stripe pattern in the chi ck down. The ground color was very dark tan, whereas the light back st ripes and the broken head stripe were similar to those of buttercup ch icks. Adults were typical buff columbian with considerable black marki ngs on the feathers. The homozygous e(bc)/e(bc) Co/Co produced chicks with a black back and a brown head, similar to those previously descri bed for the interaction between Co and the brown (e(b)) allele. The pr esence of the recessive white gene masked unexpected genetic variation at the E-locus in the Prat breed, the Buff variety carrying the domin ant wheaten (e(Wh)) instead of the buttercup allele. The sex-linked go ld (s(+)) allele was the most frequent in the White Prat variety. The silver (S), sex-linked barring (B), blue (Bl), and possibly dominant w hite (I) alleles also were present at low frequencies.