Prevalence, Risk Factors and Consequent Effect of Dystocia in Holstein Dairy Cows in Iran‪.‬

INTRODUCTION Dystocia, more commonly known as difficult calving, defined as a prolonged or difficult parturition varies from the need for increased producer attention to the loss of the cow and calf (Meijering, 1984; Carnier et al., 2000). Difficult birth is a leading cause of calf death at or shortly after birth and leads to uterine infections and more retained placentas. Several studies have implicated dystocia as contributing factors to reduced milk yield and reproductive performance (Dematawena and Berger, 1997; Fourichon et al., 2000; Lopez de Maturana et al., 2007). Genetic, environmental, and management factors have varying degrees of influence on dystocia (Johanson and Berger, 2003; Adamec et al., 2006; Mee, 2008).