DNA Extraction from blood and matrix samples
Blood samples of 128 healthy cattle aged 2−14 years were collected from regions of southern Italy (Basilicata, Calabria, Campania). All animals were pasture-free, except for 30 cattle from intensive livestock farming. Blood samples harvested in ethylenediaminetetraacetic acid (EDTA)-acid-containing vacutainers were obtained from healthy cattle at public slaughterhouses. Total DNA was extracted using a DNeasy Blood & Tissue Kit (Qiagen, Wilmington, DE, USA) according to the manufacturer’s instructions. Furthermore, DNA was extracted from samples of grass hay and maize silage (used as feed for cattle) obtained from intensive livestock farming. The DNeasy plant Mini Kit (Qiagen, Wilmington, DE, USA) was used for the extraction of hay and maize DNA, according to the manufacturer’s instructions.