Mastitis is one of the most common and costly diseases facing the dairy industry today. Annually, over $2 billion are lost to mastitis alone, with an average per-case cost estimated at $444. Nearly two-thirds of these economic losses are attributed to the consequences of subclinical infections, which result in decreased milk production, increased discarded milk and lost milk premiums.

In our study population, results showed that at the 200,000 cell/mL cut-point, composite sampling appeared to have similar effectiveness as quarter sampling to identify subclinically infected animals on a herd level. However, our results also suggest in a large population of first-lactation animals, a high proportion of coagulase negative staphylococci infections, or both, might play a large role in the effectiveness of this cut-point on herds, and optimal cut-points may vary between farms.