Irrespective of the size of your herd, making appropriate calculated decisions on individual cows with high cell counts is essential to the overall health of the herd.
Cell count is a measure of udder health with a high cell count defined as over 200,000 cells per ml. Above this measure the udder is classified as having clinical or subclinical mastitis. Cows in this bracket are one of the biggest risks to other cows in the herd contracting mastitis and therefore are a significant risk to the business.
The length of time a cow has had clinical and subclinical mastitis (and as a result high cell count) can be estimated from milk recording data. It is likely that recurrent high cell count cows are chronically infected as opposed to curing between milk recordings, and the longer this trend continues the chance of curing decreases.
Prevention of mastitis should always take priority over treatment, however with making decisions on individual cows- a balance between value and risk to the herd needs to take place.
Using clinical mastitis and cell count data, a chance of curing percentage can be calculated by using computer software (TotalVet). The possibility of getting a cure is higher in the dry period and as a result the stage of lactation should be considered. Some cows may be early in lactation, giving a decent yield but have not appeared to have cured from the previous lactation. These cows may be contributing significantly to the bulk tank cell count and risking deductions from the processors. This cow may be of little value to milk production in the herd and as a result may be best exiting the herd.
Making decisions on cell count can be easier if the cows under the spotlight are also a risk of other diseases such as Johnes, Neospora, lameness and poor fertility. Cumulative disease risks may make the cows a priority for exiting the herd.
Drying off quarters is a method used as a last resort where the offending quarter is identified and dried off permanently. There are many methods of doing this and the procedure should be discussed with a vet on an individual basis.
On a final note, every effort should be made to prevent mastitis and lower the herd incidence. If this is not achieved, culling cows from the herd can be a fruitless task as new high cell count cows will appear on the milk recording list month after month.
Sean
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