There are many types of serum, such as fetal bovine serum, calf serum, goat serum, horse serum, etc. The quality of the serum is mainly determined by the object and the process of sampling. The animals used for material collection should be healthy and disease-free and within the specified birth days. The material collection process should be carried out in strict accordance with the operating procedures, and the prepared serum should be subject to strict quality identification. Requirements in the "Procedures for the production of biological products by in vitro culture of animal cells" published by WHO:

1. Bovine serum must come from a herd or country that is documented to be free of BSE. And should have an appropriate monitoring system.
2. Some countries also require bovine serum from herds that have not been fed ruminant protein.
3. It was demonstrated that the bovine serum used does not contain inhibitors to the vaccine virus produced.
4. Serum should be sterilized by filtration through a filter membrane to ensure sterility.
5. No bacterial, mold, mycoplasma and virus contamination, some countries require no bacteriophage contamination.
6. It has a good support for the reproduction of cells.