Fetal bovine serum (FBS) is the light-brown liquid fraction of clotted fetal bovine blood. It is depleted of cells, fibrin, and clotting
factors. Although the complete composition of FBS is undefined, FBS contains high levels of growth factors and low levels
of immunoglobulins. In addition, it contains other key ingredients that are essential in supporting proliferation of cells in
culture. This product is used both in life science basic research and industrial manufacturing. FBS is a by-product of the meat
industry and is collected from bovine fetuses removed from cattle found to be pregnant at slaughter. FBS is harvested from
abattoirs that are inspected by the competent authority in the country of origin. Trained personnel following written and
approved procedures should perform collection and processing. Blood is collected in a closed system in a dedicated area
within the facility, and processed quickly to prevent hemolysis. The blood is allowed to clot and then typically is centrifuged
in a refrigerated centrifuge to separate the serum from the other components. Serum typically is removed from the clot,
transferred to labeled containers, and frozen. All manufacturers employ sterile filtration before final packaging. Additionally,
gamma irradiation provides the highest assurance of the absence of viral activity. Gamma irradiation doses of 25–40 kGy
provide significant log reduction of viral and other adventitious agents while preserving cellular growth performance.
The screening of FBS for viral contamination is accomplished by using all applicable testing described in the Code of Federal
Regulations 9 CFR 113.53 (known as full 9 CFR testing). Mycoplasma assays are performed as described in Mycoplasma Tests
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