Somatic cell counts (SCC) are readily available to every dairy farmer in the United States on a monthly basis and to farmers in most of the developed countries. Somatic cell counts are accepted as the international standard measurement of milk quality and, for this reason, are rapidly being made available in developing countries where they have not previously been utilized. Extensive data are now available worldwide on large numbers of cows concerning factors affecting SCC in milk.

Comparing these SCC data with bacteriological culture results gives a reasonable idea which factors are of greatest importance in affecting SCC levels and may clarify some misconceptions concerning changes in SCC. The basic fact is that intramammary infections are the major factor affecting SCC at the quarter, cow, or bulk tank level and no other factor will dramatically increase its level. If a dairy farmer is effective in preventing new infections (mastitis) and removes chronic cases from the herd, the herd SCC can be decreased to 100,000 or lower.