In the U.S., blood agar plates are commonly made using red blood cells from which animal?

Blood agar plates are an important medium in microbiology, particularly for the cultivation and differentiation of bacteria. The use of red blood cells from sheep in blood agar plates is preferred because sheep blood is rich in nutrients and supports the growth of a wide variety of fastidious organisms. Additionally, the composition of sheep red blood cells helps to distinguish hemolytic patterns, which are important for identifying specific bacterial species based on their ability to lyse red blood cells and form clear zones (beta-hemolysis), greenish zones (alpha-hemolysis), or no change (gamma-hemolysis) in the surrounding media.

Using horse blood is also common but less so than sheep blood in standard laboratory settings in the U.S. Human blood is usually avoided due to ethical and safety concerns, and dog blood is not typically used for these purposes as it does not offer the same advantages for microbial testing. Therefore, sheep blood remains the standard choice for making blood agar plates in laboratory environments, facilitating accurate microbiological assessments.