The Effect of a Protoporphyrin Mutant on Some Economic Traits of the Chicken

Abstract

A translocation between chromosome # 1 and the Z sex chromosome reduces egg shell protoporphyrin and acts as a sex-linked recessive. Heterozygous T/N males mated to Rhode Island Red and White Leghorn dams produced segregating sibs compared for egg traits. The mutant chromosome (T/W) daughters laid fewer and smaller eggs than sibling standard (N/W) daughters. There was no pleiotropic effect for body weight, shell breaking strength, nor shape index. Meat spot inclusions were visibly pronounced in the brown and tinted eggs as compared to the mutant white-shelled eggs. No crossovers were recovered between reduced protoporphyrin production and standard chromosomes.