FACTORS ASSOCIATED WITH CURE OF SUBCLINICAL STAPHYLOCOCCUS AUREUSMASTITIS DURING LACTATION

摘要

Staphylococcus aureus is an important cause of udder infections in dairy herds (Barkema et al., 1998a; Dingwell et al., 2003; Sargeant et al, 1998; Wilson et al, 1997). Intramammary infection (IMI) with S. aureus may result in clinical or subclinicalmastitis and is usually associated with increased somatic cell count (SCC). Staphylococcus aureus remains a problem in a variety of locations and under different management styles. Nine percent of cows in New York State (US) were S. aureus culture-positive in at least one of the quarters (Wilson et al., 1997). Keefe et al. (1997) reported that 70% of 30 randomly selected Prince Edward Island (Canada) dairy herds had at least one cow infected with S. aureus on a single herd culture. In the Ontario Sentinel project, bulk milk from 58 of 59 herds in Ontario was culture-positive for S. aureus (Kelton et al, 1999a), while 92% of the herds had at least one cow culture-positive for S. aureus (Kelton et al, 1999b). The pathogen is contagious and spreads easilywithin dairy herds (Fox and Gay, 1993; Lam et al, 1996). When multiple cows in a herd are infected, bulk tank SCC (BTSCC) increases and legal limits for BTSCC may be violated, or thresholds for premium bonus may not be met (Adkinson et al, 2001; Dekkers et al., 1996; Schukken et al, 1993). As a result, control of S. aureus mastitis remains important and necessary.