Identification of quantitative trait loci for immune traits in Landrace purebred swine

We identified the quantitative trait loci (QTL) for immune traits in a population of Landrace purebred swine. QTL analysis was carried out in order to identify genes for immune traits within a breed. Various immune traits (phagocyte activity, complement alternative pathway activity, white blood cell count, ratio of granulocyte to lymphocyte, antibody production) were measured from peripheral blood collected from 518 animals at age 7 weeks with body weight 105 kg. Three hundred and fifty five animals were typed for 107 microsatellite markers covering all autosomes. We analyzed the data from the population using identical-by-descent scores obtained from the Markov chain Monte Carlo method, as implemented with LOKI software, and formulated a putative QTL in a mixed animal model. Results of the genome scan showed evidence of significant QTL for white blood cell numbers and phagocyte activity.