Fetal Bovine Serum

Fetal Bovine Serum

Animal serum is routinely added to culture media as a source of nutrients and growth factors.

The preferred source of serum for cell culture is from calf fetuses (fetal bovine serum, commonly called FBS). FBS is prepared from fetal blood extracted from cows found pregnant at slaughter. The calf fetus is removed during evisceration and blood is extracted via cardiac puncture without anaesthesia.

However, there is now evidence of sensitivity to pain and resistance to anoxia in mammalian fetuses. In addition, although low blood oxygen levels in utero have been shown to suppress consciousness, there is emerging evidence that this suppression of conscious awareness is reversed on exposure to air. Therefore it is possible that lung inflation following removal from the uterus would expose fetuses to pain as they are bled out through cardiac puncture.

Technical disadvantages to using serum include the undefined nature of serum, batch-to-batch variability in composition, and the risk of contamination.

To avoid the possibility of pain and distress to calf fetuses:

  • Replace use of FBS with synthetic media
  • During collection of fetal blood ensure that the calf is prevented from inflating its lungs with air and breathing, and thus gaining consciousness (a refinement)

This section has been adapted from Focus on Alternatives.

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