Is there Pus in Milk?

Recently I was asked two questions; Is there pus in milk? and 2) What’s my view of Somatic Cell Count? These topics are sometimes linked so I will address both of them in this blog.

There is no pus in milk. This is sometimes confused with Somatic Cell Count (SCC) which is a measure of white blood cells naturally present in cow’s milk (also found in human milk). White blood cells enable cows to fight infection and ensure good health. SCC is a general gauge of a cow's well-being. A more elevated white blood cell count indicates an infection in a cow.

Essential to maintaining a low SCC are; 1) a clean and dry environment, 2) ample space to lie down, 3) consistent udder preparation and cleaning procedures prior to milking, and 4) maintaining an adequate vaccination program. Dairy producers strive to keep SCC low. Many dairy farmers receive a premium for low SCC. Higher SCC can increase incidence of mastitis which decrease milk production. 

This is a barn at our farm - the cows lie in clean, dry sand beds
It's important for cows to get plenty of rest and relaxation everyday
To ensure high quality dairy products, SCC’s are monitored in milk shipments using standards outlined in the U.S. Pasteurized Milk Ordinance (PMO). In the U.S., the legal maximum SCC for Grade A milk is 750,000 cells/mL. However, most milk in the U.S. has a much lower SCC. The U.S. averaged 217,000 cells/mL in 2011 down from 228,000 cells/mL in 2010.

There have been efforts by some in the dairy industry to lower the legal limit from 750,000 cells/mL to 400,000 cells/mL. I support this change but it hasn’t happened yet. Some countries who import U.S. milk products will only accept products with SCC of 400,000 cells/mL or lower. The majority of U.S. dairy farms meet this criteria.

Research shows as herd size increased, milk yield generally increased and SCC decreased. During 2010, the average test-day SCC in herds with fewer than 50 cows was 286,000 compared to 251,000 in herds with 100 - 149 cows; 217,000 in herds with 500 - 999 cows; and 184,000 in herds with over 3,000 cows. Source: USAgNet 04/28/2011

SCC varies monthly peaking during the summer months when high temperatures and humidity increase stress on cows and provide conditions more favorable for bacterial growth. SCC’s are normally lowest in the winter.  

Dairy farmers know the importance of keeping cows comfortable by providing clean and dry housing with enough space for animals to relax. As I mentioned in a recent blog, cows spend over 12 hours each day lying down and resting. We want to make sure they receive quality rest to stay healthy and productive because happy cows produce quality milk!