1. Department of Animal Science, Faculty of Agriculture, Ferdowsi University of Mashhad, 91775-1163 Mashhad, Iran
2. Department of Biosystems Engineering, Faculty of Agriculture, Ferdowsi University of Mashhad, 9177948974 Mashhad, Iran
3. Department of Animal Science, Aarhus University, AU Foulum, 8830 Tjele, Denmark