And we can distinguish between stages of subclinical and clinical mastitis. Somatic cell counts are supposed to be more or less equal to counts of white blood cells, or leucocytes, which, of course, are the cow's defense against bacterial invasions and inflammations. Therefore, milk can have the appearance of normality and still have a subclinical mastitis condition. Flakes in milk indicate severe clinical cases. In research here at the University of Delaware on the relationship of milk composition versus leucocyte levels in milk, we found some very interesting changes in milk composition depending on leucocyte level.
Milk protein consists of several kinds of proteins and non- protein nitrogen compounds.
The major milk protein of commercial interest is casein, with approximately 50 to 85 percent of the total protein. Casein is the only protein used for cheese production in most countries, with the exception of ricotta, mizithra, gjetost and other specialty whey cheeses. So if casein is 85 percent of all milk proteins, the yield for cheese making is much better than when casein makes up only 50 or 60 percent of all milk proteins. Therefore, paying for milk by its protein content really tells cheese makers nothing, whether they are getting one pound of cheese from nine pounds of milk or from 12 or 14 pounds of milk. When cheese makers buy milk, they want to get maximum yield.