1. Feed and Food Science and Nutrition Institute, Agricultural Faculty, Università Cattolica del Sacro Cuore, 29122 Piacenza, Italy
2. CERZOO, Research Center for Zootechny and the Environment, S. Bonico, 29122 Piacenza, Italy
3. CRA-SUI Pig Research Unit, 41018 San Cesario sul Panaro, Modena, Italy