Fetal Bovine Serum (FBS) alternatives are derived from newborn calves that have not been fed, collected within 4-6 hours after birth. Each batch of FBS alternatives is tested to assess its capacity to support the growth of various cell lines over three passages. At each passage, cells are subcultured to the initial seeding density. The results are compared with those from parallel experiments using a control growth medium containing previously validated reference serum.

Serum is commonly used as a supplement for cell growth due to its versatile functions and applications, including: being rich in macromolecular proteins and low-molecular-weight nutrients; providing additional sources of amino acids, carbohydrates, and vitamins; enhancing the buffering capacity of the culture medium; binding or neutralizing toxic substances; reducing cellular oxidative stress and apoptosis; and supplying growth-promoting factors that aid in cell adaptation to the culture environment.