Fat

The fat content of cow’s milk averages about 3.7% but varies from less than 3 to over 6 percent, depending on breed, stage of lactation, and a number of environmental conditions.

Protein

Fluid milk has about 3.5% protein. Amount vary according to breed, stage of lactation, and certain environmental situations.

Somatic Cell Count (SCC)

The somatic cell count (SCC) is commonly used as a measure of milk quality. Somatic cells are simply animal body cells present at low levels in normal milk. High levels of these cells in milk indicate abnormal, reduced-quality milk that is caused by a intra mammary bacterial infection (mastitis). The cell count for "normal" milk is nearly always less than 200,000 cells/ml. Higher counts are considered abnormal and indicate probable infection.

Lactose

Milk sugar. Lactose content of milk averages about 5%.

Other Solids

Lactose plus Ash (The residue remaining after complete combustion at 5000 to 6000 C of a feed or feed product during proximate analysis.)

Milk Urea Nitrogen (MUN)

Normal values are considered to be between 12 to 16 mg/dl. High MUN levels can be due to an excess of dietary and/or soluble protein, stress (including disease, exercise from grazing or extreme cold), or too little rumen available energy in the diet. Low MUN may be a result of an insufficient level of protein, too little degradable protein, or insufficient energy in the diet. As the non-fiber carbohydrate (NFC), crude protein ratio increases, MUN decreases. MUN also decreases as lactation progresses.