ABSTRACT
Mastitis is one of the most economically important diseases in dairy production, and it is defined as an inflammation of the mammary gland. Intramammary infections (IMI) continue to be the most important cause of mastitis in dairy cattle, accounting for 38% of the total costs of the common production diseases (Kossaibati and Esslemont, 1997). In the last decade, several groups have estimated the losses associated with clinical mastitis, and the average costs per case (US$) of Gram-positive, Gram-negative and other microorganisms were $133.73, $211.03 and $95.31, respectively (Cha et al., 2013; Gröhn et al., 2004). These costs include treatment, culling, death and decreased milk production. In addition to reduced cow welfare and increased veterinary costs, episodes of mastitis are associated with reduction of milk production (Bar et al., 2007; Schukken et al., 2009), decreased fertility (Hertl et al., 2010; Santos et al., 2004), and increased culling and death risk (Hertl et al., 2011).
