Difference in the Ct values of homozygous early feathering (EF), heterozygous late feathering (LF), and homozygous LF animals. A) Comparison of K locus components on the Z chromosomes of different genotypes. The red striped box and blue striped box indicate the duplicated blocks of genetic sequence. The dark blue line is marker STS_control and the green line is marker STS_break. B) The theoretical curves of the qPCR. In k+/k+ animals the difference between Ct (Break) and Ct (Control) will be -Ct (Control). For k+/K animals the theoretical difference will be 1 Cycle. For K/K animals the difference will be 0.