Within the PigSNP project SNPs will be identified that are known to be segregating within commercial European pig breeds. Using the Solexa sequencing technique a representation of the genome is directly sequenced to high redundancy. This is achieved by digesting the DNA with a restriction enzyme and sequencing fragments within a specific size range (i.e. 250 bp). The strategy used is based on sequencing a mixture of the DNA from 5 individuals of a single commercial breed to 20 X depth. Furthermore, the use of 5 individuals per breed (10 haplotypes) will ensure the identification of SNPs with high minor allele frequencies. This approach ensures that SNPs identified will be informative within the commercial line and therefore will be useful not only in experimental QTL crosses but also for genomic selection in current commercial breeding lines. The combination of new generation sequence technology (Solexa) combined with WITHIN breed SNP identification of major SNPs is particular innovative and timely. The SNPs identified will be available to be included in high density SNP panels (within existing international ongoing collaborations) that will be used to genotype available commercial pig breeds. This will aid in the further fine mapping of previously identified QTL within these commercial crosses. Within the project we will use the identified SNPs for fine mapping 2-3 previously identified QTL on chromosomes 2 and 4 identified within an experimental MeishanxEuropean white cross and within a commercial finisher population respectively. Both populations have been used extensively for the identification of several QTL for fatness, carcass and meat quality traits. Within the project it is aimed to identify between 10 and 20 thousand SNPs each for 4 different commercial breeds. QTL fine mapping will be done using the Illumina Golden Gate assay.