Respiratory disease is the second leading cause of death losses (scours is the first) in un-weaned heifer calves. Respiratory problems have increased by 34 percent in the last twenty years resulting in nearly 21 percent of all newborn calf losses (NAHMS. 2007). Heifers that survive continue to perform poorly as adult cows. In order to prevent this costly problem it is important to address both determinant and predisposing causes.
Garcia, A. D. and Daly, R., "Respiratory disease in young dairy calves." (2010). Dairy Science Publication Database. 575.