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A brief history of SCC regulations in the US


he relationship between somatic cell count (SCC) and abnormal milk has been known for more than 100 years. In 1910, in the Journal of Infectious Disease, Prescott and Breed wrote: "For some time sanitarians have felt that it was important to be able to determine the number of body cells in milk. Large numbers have been held to be undesirable in as much as such conditions seem to be associated with abnormal conditions of the udder." Fifty years passed before action was taken on a national level in the US to establish regulatory limits on milk somatic cell counts. In 1963, the National Conference on Interstate Milk Shipments (NCIMS)1 appointed an Abnormal Milk Committee to study mastitis problems and develop a course of action. In May 1965, the NCIMS Abnormal Milk Committee presented a resolution requiring laboratory examinations or screening procedures for abnormal milk to be conducted at the same frequency as for bacteriological tests. The NCIMS voting delegates approved the resolution by a close vote. The effective date was July 1, 1967, with a strong recommendation that a screening program be in place by July 1, 1966. At the 1967 Conference, the NCIMS Abnormal Milk Committee presented the Abnormal Milk Program, which was approved and incorporated into the Pasteurized Milk Ordinance (PMO). As stated in The History and Accomplishments of the National Conference on Interstate Milk Shipments: “It is certain the subject of consuming interest at the [1967] Conference was the abnormal milk program. Emotions ran probably as high as they did during the ‘Methylene Blue’ discussions of previous years.” The Abnormal Milk Program phased in a SCC limit of 1,500,000 cells/ml. Phase I, effective July 1, 1967, required that screening procedures for the presence of abnormal milk be made at the same frequency as bacteriological tests (at least four times in each sixmonth period). Phase II, effective July 1, 1968, provided procedures for producer notification and farm inspection when SCC exceeded the limit. The final phase (III), effective July 1, 1970, added a penalty clause for non-compliance. Permit suspension occurred if SCC limits were exceeded three out of five times. The original recommendation by the Abnormal Milk Committee called for a SCC limit of 1,000,000 cells/ml; however, this was changed to 1,500,000 cells/ml.

“It is certain the subject of consuming interest at the [1967] Conference was the abnormal milk program.”

50 Years of Milk Quality

During the 1970s, there were several attempts to change the SCC standard. At the 1971 NCIMS, much time was spent on the abnormal milk program and particularly on the effort to reduce the SCC limit from 1,500,000 to 1,000,000 cells/ml. The vote held the standard at 1,500,000 cells/ml. In 1975, a proposal was submitted to drop the SCC standard to 1,000,000 cells/ml. NCIMS delegates voted to maintain the SCC action level at 1,500,000 cells/ml which was in agreement with the action level recommended by the NCIMS Abnormal Milk Committee. An NMC ad hoc committee on abnormal cell counts also opposed a drop in the SCC standard at this time. Then in 1979, delegates rejected a proposal submitted by the NCIMS Abnormal Milk Committee to reduce the SCC limit to 1,300,000 cells/ml. NCIMS delegates finally approved a proposal in 1983 to reduce the standard to 1,000,000 cells/ml. The effective date was July 1, 1986. During the NMC annual meeting prior to the 1983 NCIMS, a concerted effort was made to obtain a recommendation from NMC regarding the proposed action level. However the NMC Board of Directors declined to act. A proposal to reduce the SCC limit further, to 750,000 cells/ml, was submitted in 1989, but no action was taken by NCIMS. In 1991, NMC submitted a proposal to NCIMS recommending a reduction in the SCC limit to 500,000 cells/ml. Voting delegates approved an amended NMC proposal which set the SCC standard at 750,000 cells/ml effective July 1, 1993. NMC submitted another proposal in 1991 to establish a state/national program to collect and report bulk talk SCC data from all commercial herds in the US at least once per year. Although the proposal was not approved, a resolution supporting NMC’s efforts to develop a national SCC database was adopted by the delegates. The resolution encouraged states to voluntarily provide NMC with at least one bulk tank SCC for each dairy herd annually. The first proposal recommending a reduction in the US SCC regulatory limit to 400,000 cells/ml (the same as the SCC standard in the European Union) was submitted to NCIMS in 1997 by Dr. K. Larry Smith, The Ohio State University. No action was taken. For the next four NCIMS conferences (1999, 2001, 2003 and 2005), NMC spearheaded efforts to lower the SCC regulatory standard to 400,000 cells/ml. NMC felt that a SCC limit of 400,000 cells/ml would lead to harmonization of standards for international trade of dairy products; reduce the risk of residues and potential human pathogens and their toxic products in the milk supply; and improve consumer confidence in the safety and wholesomeness of the US milk supply.


NMC Commemorative Booklet  
NMC Commemorative Booklet  

This book is a collection of the past 50 years of mastitis control, milk quality, the history of the National Mastitis Council, personal rec...