Factors Affecting Days Open in Holstein Dairy Cattle in Khorasan Razavi Province, Iran; A Cox Proportional Hazard Model

A.R. Bahonar, M. Azizzadeh, M.A. Stevenson, M. Vojgani and M. Mahmoudi

Journal of Animal and Veterinary Advances 8 ( 4 ): 747 - 754 , 2009