As farms work towards lower Bulk Milk Cell Counts, spurred on by quality premiums from processors, the question “Can cell counts be too low?” is often raised.

The biology prompting this question is that the somatic cells measured in milk are predominately white blood cells, and white blood cells are the body’s first line of defence to infection.

“Can you go to low?” is actually asking whether cows or herds with low cell counts are at greater risk of mastitis.

Cows that have healthy quarters with no infection or inflammation have cell counts in their milk between 20,000 to 200,000 cells/mL - but nearly all are below 100,000 cells/mL.

These ‘resident’ cells are a cow’s early warning system. If bacteria enter the udder, the white cells release chemical messages to call in additional defence cells from the blood stream to help eliminate the bacteria and repair damaged tissue. Under severe bacterial challenge, billions of white blood cells may actually be required to overpower the infection.

Research suggests that an effective, natural defence relies on cells being rapidly recruited from the blood stream and acting quickly to eliminate bacteria at the infection site. It is more important to have cows in good body health, with readily responsive immune systems, than to have lots of cells waiting in milk.

Herds with low BMCCs (below 100,000 cells/mL) are not more prone to infection, and there are real productivity benefits from having low cell counts.

Image and caption

 “There are real productivity benefits from having low cell counts”

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Keywords
BMCC, biology, bacteria

Word length
289