The use of blue-splashed white down in color sexing crosses.

Since the blue-splashed white (BSW) phenotype represents an alternative type of near-white down, a study was undertaken to see if it could be used in color sexing crosses as a background for the expression of sex-linked alleles at the silver (S, s+) and barring (B, b+) loci. The BSW is produced by homozygosity for the autosomal mutation, Bl, which results in blue plumage when heterozygous (Bl/bl+). The Bl/bl genotype reduces eumelanin in the down to a light grayish color. Also, like dominant white (I), it is relatively ineffective against pheomelanin. Silver (S) and gold (s+) were readily identifiable on BSW down in the presence of e+/e+ (wild type) and to a lesser degree with eb/eb (brown). Sexing was not possible using S and s+ with either E/-(extended black) or eWh/eWh (dominant wheaten). The addition of Co (columbian) enhanced the visual differentiation of silver and gold on all but the E/-background. As it does in the presence of dominant white, Co resulted in a marked increase in red pigmentation in subsequent plumages. The use of barring (B) was also an effective method for sexing chicks on a Bl/Bl E/-background. The presence of E was necessary to provide the even grayish down coloration in the head region for the expression of the B-induced head spot. the amount of red pigment in the broiler and adult plumage of the sex-linked offspring from this cross was further reduced by incorporating silver (S).