Fetal bovine serum is derived from the blood of fetal calves and contains the nutritional and macromolecular growth factors that are essential for the growth and maintenance of cultured cells.

Fetal bovine serum (FBS) and fetal calf serum (FCS) are used to describe the same product and are interchangeable, although the use of FBS is more common. Bovine calf serum (BCS) has notably different characteristics than fetal bovine serum and is derived from calves post-birth, ranging from birth to 36 months. BCS typically has lower levels of growth factors and higher levels of proteins and antibodies than FBS.

Yes. For more information: https://www.genengnews.com/insights/high-quality-fbs-may-come-from-any-authorized-country-of-origin/

In almost every instance, the serum is not contaminated. Occasionally thawed serum will appear cloudy. It is usually the result of normal serum components. Fibrin (a non-globular protein involved in the clotting of blood) is most common. Fibrin appears in small quantities as a fine flake or may occur as a lump of a semi-solid substance. The presence of this material does not alter the serum’s performance and may be mistaken for microbial contamination. If the turbidity is a concern, it can be removed by filtration through a 0.45µm filter. However, the sediment may clog many lab-scale filters. If necessary, allow the serum to stand. The sediments will eventually fall to the bottom of the bottle and the serum can be decanted.