1. Department of Veterinary-Medical Science , University of Parma , Str. dell’Università, 12, 43121 Parma , Italy
2. Department of Animal Science , University of Lleida , Avda. Rovira Roure 191, 25198 Lleida , Spain
3. Agrotecnio Center , University of Lleida , Avda. Rovira Roure 191, 25198 Lleida , Spain
4. Transfer in Bovine Reproduction SLu, Capuchinos 18, 22300 Barbastro , Spain