A total of 120 serum samples of Large White piglets were selected from a well defined and characterized repository database, presently containing more than 20,000 swine samples from 18 different farms of the Lombardy region, Italy. Selection of the piglets aimed to minimize environmental factors and experimental conditions that might influence the results [39] . Hence, all piglets were from the same breed (Large White), had similar ages (weaning: 45-50 days), and their sera showed a low and comparable amount of hemoglobin (calculated as shown below).