[1] CNR, Natl Res Council, ISPAAM, Lab Anim Cytogenet & Gene Mapping, I-80125 Naples, Italy
[2] Leibniz Inst Farm Anim Biol FBN, Res Unit Mol Biol, Dummerstorf, Germany
[3] Univ Bari, Dept Anim Prod, I-70121 Bari, Italy
[4] Univ Naples Federico 2, Dept Soil Plant Environm & Anim Prod Sci, Naples, Italy