Outline of the speed congenic approach used to capture genome-wide growth and obesity QTL. Details of the congenic matings are outlined in "Methods". The matings used to construct the MMU2 speed congenic panel are listed on the left of the figure, along with the expected and observed % heterozygosity at each generation. % heterozygosity is defined as the number of markers heterozygous B6 (or HG)/CAST as a percent of the total number of markers typed (N = 79). The right side of the illustration lists the matings used to construct the MMU1, 5, 8, 9, 11 and 17 speed congenic strains, along with the expected and observed % heterozygosity at each generation.