# Biological and Technical Challenges Related to Cultured Meat Production
## 3 Challenges Related to Cultured Meat Production
### Biotechnological Challenges
#### 3.1.4 Fetal Bovine Serum: Ethical Challenges  
One of the cornerstones of cellular agriculture is to ensure the sustainability of the production process. Today, almost all cell cultures involve the addition of FBS to the culture media to ensure optimal growth. Fetal Bovine Serum is an extremely complex mixture that, in addition to providing a large number of constituents such as fatty acids, lipids, vitamins, carbohydrates, inorganic salts, proteins (more than 1800), and more than 400 metabolites, provides essential hormonal factors for cell growth and proliferation. Parallel to the nutritive function, FBS ensures adhesion and diffusion factors that act as germination points for cell attachment. In addition, it allows minimizing physical damage caused by pipette handling and agitation [34; 35]. Although the positive aspects of the use of FBS are widely demonstrated and discussed in the literature, it is also true that it presents multiple problems related to sustainability and ethicality by clashing with the basic principle of cellular agriculture.  
The collection of FBS has always caused a stir. When a pregnant cow is slaughtered, the fetus is removed and a cardiac puncture is made in the still-beating heart to collect serum under the most aseptic conditions possible, causing first enormous suffering and then death [34]. It is essential that fetuses are at least 3 months old to ensure anatomical formation of the heart to ensure perfect serum collection [36]. The exact amount of FBS produced and sold in the world is unknown. However, it is estimated that approximately 800 thousand liters of FBS is sold annually, which translates into approximately 2 million fetuses sacrificed [35]. However, these numbers are expected to increase exponentially due to a rising use of cell cultures for, recombinant proteins, vaccines, and therapeutic diagnostic treatments [37]. From a process sustainability perspective, the FBS market is highly dynamic, leading to continuous price fluctuation and making it unsustainable on a large scale [38]. Price and availability fluctuate due to changes in the number and cost of cattle raised worldwide, import regulations, beef and dairy prices, costs, and weather conditions [34].  
FBS being an animal derivative is characterized by qualitative and quantitative differences dependent on the batch to which it belongs and therefore on the animal used for sampling, which makes it necessary to test the product before its use [39]. In addition to issues regarding variability, serum may contain varying amounts of endotoxins, hemoglobins, and other factors adverse to cell growth, as well as being potential sources of microbial contaminants such as fungi, bacteria, mycoplasma, viruses, or prions introduced during the sampling phase [34]. In addition, many other substances within FBS are still unknown, which prevents us from studying and knowing the possible effects on cell viability [40].  
Therefore, it is necessary to find viable alternatives to FBS to support the large-scale production of cultured meat.