The National Conference on Interstate Milk Shipments (NCIMS) meets every other year to consider proposed changes to the Pasteurized Milk Ordinance (PMO) and allied documents that establish the condition under which 'Grade A' milk is inspected, produced, hauled, processed, stored and packaged in the US. Conference participants include representatives from industry, government and educational institutions. Voting delegates are limited to state rating and enforcement agency representatives. All conference actions are subject to review and concurrence by the US Food and Drug Administration. The 2011 Conference will be held April 29 - May 4, 2011, in Baltimore, Maryland.

The NMC has submitted a proposal to this year's Conference to lower the somatic cell count (SCC) regulatory limit in the US from 750,000 to 400,000 cells/ml by January 1, 2014.

In addition, regulatory action would be based on a three-month rolling geometric mean SCC rather than the current three out of five consecutive samples exceeding the SCC limit.

This is the fifth proposal that NMC submitted to NCIMS to lower the SCC limit to 400,000. Previous NMC SCC proposals were considered (and subsequently rejected by NCIMS) in 2005, 2003, 2001, and 1999.

The last time NCIMS took action to lower the SCC limit was at the 1991 Conference, when the voting delegates approved an amended NMC proposal which lowered the SCC from 1,000,000 to 750,000, effective July 1, 1993. The original proposal submitted by NMC was to lower the SCC from 1,000,000 to 500,000 over the course of three years.

Lowering the SCC Regulatory Limit; Suggested Timetable

  • January 1, 2012 - Maintain the current SCC standard and means for determining compliance but phase in the adoption of a rolling geometric mean calculation for herd SCC. The rolling geometric mean should be operational by all state regulatory agencies by December 31, 2012
  • January 1, 2013 - Lower the SCC standard to 550,000 based on a rolling geometric mean
  • January 1, 2014 - Lower the SCC standard to 400,000 based on a rolling geometric mean.

Why Lower the SCC?

  • improved consumer confidence in the safety and wholesomeness of the US milk supply
  • improved consumer confidence that the milk supply is produced by healthy cows
  • harmonization of standards for international trade of milk and milk products
  • improved competitive position of the US dairy industry in the global market place
  • reduced risk of antimicrobial residues in milk
  • reduced risk of the presence of human bacterial pathogens and their toxic products in the milk supply
  • greater profits to producers through decreased herd level of mastitis

Why Use a Rolling Geometric Mean?

  • the geometric mean is the mathematically correct statistic to use for averaging SCC data
  • using a geometric mean will lead to increased international harmonization of standards
  • a rolling geometric mean based on three consecutive monthly samples reduces the possible volatility in herd SCC observed in some herds where a few cows can have a major impact on SCC, and/or the volatility observed with season of the year and adverse weather conditions
  • it is easier for herds to stay in compliance with SCC regulations when a geometric mean is used
  • a rolling geometric mean calculation for herd SCC provides producers with a valuable management statistic
  • calculating a geometric mean is easily accomplished with computer software or scientific calculators

Source: NMC