by Amanda Smith, Associate Editor
The health and economic repercussions of subclinical mastitis are well documented. Screening of udder health in early lactation has the potential to limit the disease's monetary impact and improve treatment success. The latter becomes even more critical as public scrutiny forces us to justify antibiotic use.
Yet, the optimal time to screen cows in early lactation has not been determined. To put firmer data to this, Azizoglu et al., cultured 42 cows, four times during the first month of lactation, to assess the best time to monitor early-lactation infections. Their results were shared at the National Mastitis Council annual meeting.
Over the study, 160-quarter milk samples were collected and cultured on Days 2, 4, 14 and 28 of lactation. Days 2 and 4 were designated as early. A quarter of samples were culture positive at any point. The majority (87 percent) of infected quarters occurred in early lactation.
Of the early infected quarters, 40 percent self-cured by Day 14 and showed no later infection. Among the 20 quarters that were still infected on Day 14, only three self-cured by Day 28.
The authors note that intervention based on samples collected before five days in milk may result in management error due to the high self-cure rate. Since limited self-cure occurred by Day 28, the optimal time to screen is likely between five and 14 days postcalving.
