What is fetal bovine serum? 

Introduction 

For over sixty years, serum has been used as a key supplement for growing and maintaining cells in culture. Serum contains a mixture of proteins, hormones, minerals and other growth factors and is added to media as a growth supplement. Serum, including fetal bovine serum, is the liquid fraction of clotted blood which is depleted of cells and clotting factors. Serum differs from plasma in that an anti-coagulant is never added to the blood after collection from the animal. Serum is prepared by centrifuging the blood remaining blood cells are separated from the liquid, then stored frozen until further processing, filtration, and bottling.

This article provides an overview of common terminology for bovine serum including fetal bovine serum as well as an introduction to fetal bovine serum collection and standardization.

What are the different types of bovine serum?

There are a few key classifications of animal sera including fetal, newborn, calf, adult and donor. Bovine serum is classified according to the age of the animal from which blood was collected.

• Fetal bovine serum is sourced from fetuses.
• Newborn bovine serum is sourced from calves less than twenty days of age.
• Calf bovine serum is sourced from calves aged between three weeks to 12 months.
• Adult bovine serum is sourced from cows more than 12 months old.
• Donor bovine serum can be sourced from cattle 12 months or older.

The age of the animal is an important characteristic because it can impact the composition of the blood and the final product which can impact your cultures depending on the cell types used.

What is fetal bovine serum? 

Fetal Bovine Serum (FBS) is the amber-colored supplement remaining after the natural coagulation of blood; it is commonly further processed to remove remaining blood cells which is then widely used to supplement media in cell and tissue culture.

The process of fetal bovine serum collection begins at abattoirs, also known as slaughterhouses. As a byproduct of the meatpacking industry, FBS can only be drawn in licensed facilities and in aseptic conditions that meet federal regulations to ensure safety and quality. First discovered during the 1960’s, FBS is the serum derived from blood drawn from a bovine fetus. FBS contains over a thousand different growth promoting factors including proteins, electrolytes, lipids, carbohydrates, hormones, enzymes, growth, and attachment factors, which are necessary in supporting cell growth.

How is fetal bovine serum tested and standardized?

The International Serum Industry Association (ISIA) is an association comprised of collectors, producers, distributors, and end users of animal-derived products. Formed in 2006, the primary objective is to promote ethics within the industry and to focus on the safe sourcing and safe use of serum and animal-derived products. The ISIA is also committed to providing quality control standardization in labeling and education to stakeholders on the various aspects of sourcing and use of serum.

Through safety standards, ISIA has identified a minimum of 15 serum quality tests required for each batch including chemical and biochemical tests such as endotoxin, total protein, hemoglobin, sterility testing, viral testing, and radial immunodiffusion.

To learn more about ISIA and the standardization of serum types, visit the ISIA website.

Definitions of common FBS terms 

Term	Definition
Lot or Batch	A unit of serum that is processed, produced, and manufactured under essentially the same conditions and at one time. Serum also has the same characteristics and quality specifications creating a complete lot or full batch.
Country of Collection	The country where the animal was slaughtered and the blood was collected or, in the case of donor animals, where the blood was collected. This includes animals born and raised in the country of collection, as well as imported animals, and may include animals imported for immediate slaughter. This is the country shown on the label as origin. The Country of Collection is required to be shown on the Certificate of Analysis (CoA).
Country of Manufacturing	This is the country where filtration, bottling, and labeling occur and includes any other processes performed prior to filtration and bottling.
Specialty FBS	This is semi-processed FBS or sterile filtered FBS that has been subjected to one or more modification processes, or that has been enhanced or altered in any way. Examples are Dialyzed, Charcoal Stripped, IgG stripped, or pH treated.
USDA Origin	Serum derived from blood aseptically collected in USDA approved abattoirs.
US Origin	Serum derived from blood aseptically collected in US approved abattoirs.

How is fetal bovine serum processed and stored?

In the FBS manufacturing process, whole blood is collected from abattoirs where cows pass both veterinary pre- and post-mortem inspections aseptically in disposable sterile bags and allowed to clot. Once the serum separates from the clot, it is pooled and frozen. Controlling the initial collection is a crucial factor in the quality of the final serum product. Once raw material is thawed and tested, only the accepted material is pooled and blended under refrigerated conditions and membrane filtered.

After filtration, the serum is then dispensed into bottles by an aseptic filling process which has been validated to insure sterility of the final product. Serum products are produced in a controlled environment (clean rooms) designed to carefully control air pressure and particulate matter. After filling, the final product is quickly frozen between ≤-10  and held in quarantine until all quality control tests have been completed.

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Trusted by both academic and industry customers, Captivate Bio has become the go-to supplier for premium and specialty serum solutions with fast service and consistent supply. Contact our team today to request a free quote on our premium FBS, specialty FBS, animal sera, or human platelet lysate (an FBS alternative).  

Learn More

• Overview of fetal bovine serum and its applications in eukaryotic cell culture
• International Serum Industry Association
• Explore Captivate Bio’s comprehensive list of sera products