Bovine serum is categorised based on the age of the animals when a serum collection is made. The age of the animal is an important consideration because it impacts on the characteristics of the serum:
- Foetal bovine serum comes from foetuses
- Newborn calf serum comes from calves less than three weeks old
- Calf serum comes from calves aged between about three weeks and one year old
- Adult bovine serum comes from older cattle (i.e. older than 12 months)
- Donor bovine serum comes from Donor animals which can be up to three years old
FBS is the most sought after and also most costly serum. It has the advantage over other sources of having the lowest antibody levels and high growth factor concentrations.