1. Instituto de Ganadería de Montaña (CSIC-Universidad de León), Finca Marzanas, Grulleros, León, Spain
2. Institute of Zootechnics, Università Cattolica del Sacro Cuore, Via Emilia Parmense, Piacenza, Italy
3. Institute of Environmental and Agricultural Chemistry, Università Cattolica del Sacro Cuore, Via Emilia Parmense, Piacenza, Italy