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Somatic cell count (SCC) is an indicator of the quality of milk. White blood cells known as leukocytes constitute the majority of somatic cells in question. The number of somatic cells increases in response to pathogenic bacteria like ''Staphylococcus aureus'', a cause of mastitis. The SCC is quantified as cells per ml. General agreement rests on the values of less than 100,000 cells/ml for uninfected cows and greater than 250,000 for cows infected with significant pathogens. The California mastitis test provides a cow-side measure of somatic cell count. The somatic cell count in the milk also increases after calving when colostrum is produced. ==Somatic cell count and bacteria plate count== The methods of determining Grade A milk quality are well established, and are based on the somatic cell count and the ''bacteria plate count''. Generally a lower somatic cell count indicates better animal health, while the bacteria plate count indicates improved equipment sanitation. Somatic cells originate only from inside the animal's udder, while the bacteria are usually from external contaminations, such as insufficient cleaning of the milk transport equipment or insufficient external cleansing of the cow's udder and teats prior to milking. Milking equipment can also be accidentally knocked or kicked off an animal onto the floor, and contaminants on the barn floor can be sucked into the milk line by the system vacuum. A filter sock or filter disk in the pipeline prevents large particulate contaminants from entering the milk bulk tank, but cannot remove bacterial contamination once it has occurred. For example as defined by the State of Indiana administrative code,〔http://www.in.gov/legislative/iac/〕 grade A milk shall meet the following standards:〔State of Indiana Administrative Code, TITLE 345 INDIANA STATE BOARD OF ANIMAL HEALTH, ARTICLE 8. DAIRY PRODUCTS, 345 IAC 8-2-3 Manufacturing grade dairy farms; construction; operation; sanitation, page 11 http://in.gov/legislative/iac/T03450/A00080.PDF〕
As established, these measurements are taken daily from the milk bulk tank and not from individual cows. This is because testing of individual animals at each milking would be expensive, but it also means that milk from a sick cow is diluted and averaged down by the healthy animals. The huge bulk tanks at large farms are accommodating of more sick animals in the herd, without the sick animals affecting the overall milk quality rating. However many different state and governmental agencies (including FDA) inspect each load of milk delivered to the processing facility as well as the processing facilities themselves to ensure that all milk processed through those facilities is safe for all consumers.〔4. U.S. Food and Drug Administration - 2007 Pasturized Milk Ordinance http://www.fda.gov/Food/FoodSafety/Product-SpecificInformation/MilkSafety/NationalConferenceonInterstateMilkShipmentsNCIMSModelDocuments/PasteurizedMilkOrdinance2007/ucm063876.htm〕 As discussed in the paper ''Guidelines for Using the DHI Somatic Cell Count Program'':〔Guidelines for Using the DHI Somatic Cell Count Program, Author: G.M. Jones, Professor of Dairy Science and Extension Dairy Scientist, Milk Quality & Milking Management, Virginia Tech, Publication Number 404-228, posted March 1998 http://www.ext.vt.edu/pubs/dairy/404-228/404-228.pdf〕
In Canada,〔(Canadian Dairy Milk SCC Standard Change to 400,000 )〕〔(Harmonisation et qualité du lait cru - Règles et politiques au sein des provinces )〕 European Union, Australia, New Zealand and Switzerland, the somatic cell count shall be not more than 400,000 cells per milliliter, it is 750,000 in the USA and 1,000,000 in Brazil.〔(Determining U.S. Milk Quality Using Bulk-tank Somatic Cell Counts ) - Centers for Epidemiology and Animal Health September 2012〕 Bacteria in milk can come from sources other than the animal. Over time the milking pipeline and equipment can become coated with residues such as ''milkstone'' which are not removed by standard detergents and require periodic flushing of equipment with high strength corrosives. Automatic washing equipment for the bulk tank may not effectively clean all interior surfaces, and does not clean the exterior of the bulk tank at all. Milk processors and co-ops purchasing milk routinely award farmers for having the lowest possible SCC counts via "quality bonuses" added to each milk payment to the dairyman. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「somatic cell count」の詳細全文を読む スポンサード リンク
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