When can sensors tell you that a cow is chronic?

Somatic cell counts and conductivity are widely used as indicators for the detection of mastitis in cows. Can our sensors move further than detection of mastitis and identify when mastitis gets chronic?

To answer this question, John Bonestroo, industrial PhD student at DeLaval, analysed the progression of mastitis based on VMS conductivity and OCC (online cell count) patterns.

 

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“If cows do not recover within 3 to 4 weeks after onset of a subclinical mastitis, their condition will likely remain chronic,” says John. The project team with researchers from Swedish University of Agriculture, Wageningen University and DeLaval supervisor Ilka Klaas, Dairy Development director, just published their results in the Journal of Dairy Science.

“The new sensor-based definitions of chronic mastitis are an important step towards efficient sensor-based mastitis management,” says Ilka.

Method

The data was retrospectively collected from 15 European and American VMS herds with OCC. In total, 2 584 cases of mastitis were followed over 13 weeks. Mastitis was defined as an initial SCC above 200 000 cells/ml. After this, it was determined whether cows were treated by using milk diversion from the bulk tank and whether they would eventually recover. “Based on the recovery and treatment status, we followed SCC and conductivity patterns in four groups: treated – recovered, not treated – recovered, treated – not recovered, and not treated – not recovered,” John continues.

Result

The results indicate that for SCC, if a case recovers, it is most likely to recover within 3 to 4 weeks for both treated and untreated cases. The variation of conductivity between milking quarters tended to stabilize between 3 to 4 weeks as well.  The findings indicate a chronicity threshold of 3 to 4 weeks of high SCC or conductivity values. After this, it is very likely that a case will remain chronic.

“Now that we have defined chronic mastitis, our next step is to explore the implications of chronic mastitis and investigate how we best can implement the results,” says John. More results will follow soon.

Read the paper in the Journal of Dairy Science
https://www.journalofdairyscience.org/article/S0022-0302(20)31066-3/fulltext