Is a low cell count bad?

Authors: Kehrli Jr, Marcus

Submitted to: Hoard's Dairyman
Publication Type: Popular Publication
Publication Acceptance Date: 4/25/2019
Publication Date: 4/25/2019
Citation: Kehrli Jr, M.E. 2019. Is a low cell count bad?. Hoard's Dairyman. 164(8):238.

Interpretive Summary:

Technical Abstract: When your somatic cell count is that low, it’s good indication that your environmental exposure to pathogens is very low. The critical question is whether or not those cows are capable of responding and raising their somatic cell count when exposed to pathogens. Organisms like Escherichia coli love to grow in milk. E. coli numbers in milk can double every 20 minutes, so it’s very important that cows have a rapid immune response. If you are at 50,000 somatic cell count, you are doing a fantastic job of milking your cows, but they can still get mastitis. The key is how quickly that cow can respond by mobilizing neutrophils from the bloodstream into the udder where the pathogen is located. Under optimal immunity conditions it can take a couple of hours for the cow to get neutrophils from the bloodstream into the milk. If the cow has a large pool of neutrophils in the bloodstream, there are more cells that can respond quickly within a few hours of infection. This situation will reduce the bacterial burden the animal has to deal with. A more important measure is that a cow goes from 50,000 to 500,000 cells per milliliter very quickly, so that all the bacteria are killed, and then goes back to the lower level within a few days or hours. That is not something we are going to be able to detect with monthly somatic cell count reports. The somatic cell count is a single time point measurement. The inflammatory response in a research setting is best measure by repeated sampling every couple hours over a period of a few days until the infection is resolved – not something that is practical in a production setting.