Association between microsatellite markers of sheep chromosome 5 and faecal egg counts

Abstract

This study analyses the associations between alleles at seven microsatellite markers located at the sheep chromosome 5—where the interleukin IL-3, IL-4 and IL-5 genes were mapped—and faecal egg counts (FEC) in two different flocks. The associations were analysed by estimating the average excess of alleles at each microsatellite marker on FEC. Three of the studied markers (CSRD2138, OarAE129 and TGLA176) showed significant associations with FEC in the Corriedale flock. Seven alleles at these microsatellite loci were associated with FEC and their effects ranged from −28 to +20%, relative to the FEC population mean. On the other hand, four alleles at CSRD2138 and TGLA176 microsatellite markers had significant associations with FEC in the Polwarth mob, with effects varying from −22 to −5%, relative to the FEC population mean. All microsatellites investigated presented high diversity in both flocks. Some alleles were breed specific. The CSRD2138 ∗A allele was the only marker associated with consistent reductions in FEC for both breeds. These results indicate that markers or genes nearby the interleukin genes, such as the CSRD2138, might enhance host resistance to internal parasites in sheep by probably increasing effector cells and antibody responses.