A typical modern broiler chicken breeding programme, represented as a pyramid where each level represents a generation. The great-grandparent line/purelines on the top of the production line are where desired traits are selected across four lines. Within the pedigree segment are the specific male and female lines, with the males typically selected for heritable growth and production traits and the female lines selected for early growth and conformation (Anthony, 1998). The commercial broiler (fifth generation) is derived from the cross of a male and female parent line.

The PCSA against fascicle length for the pelvic limb muscles of the purelines A, B, C and D. Values (means) are normalized for comparison. The colour of the labelled data points for each muscle matches the colour of that particular muscle in the anatomical diagram above. The uncoloured points represent the remaining muscles of the pelvic limb.