Blood agar bases are typically supplemented with 5 - 10% sheep, rabbit, or horse blood for use in isolating, cultivating, and determining hemolytic reactions of fastidious pathogenic microorganisms. Without enrichment, blood agar bases can be used as general purpose media.
In 1919, Brown experimented with blood agar formulations for the effects of colony formation and hemolysis.
In Blood Agar Base, Improved, the formula was modified slightly to enhance organism growth and neutralize any toxic metabolites. Blood Agar Base media are specified in standard method procedures for food testing.

Composition:
Agar: 15g/lit.
Pancreatic digest of casein: 13g/lit.
NaCl: 5.00 gm/lit.
Yeast extract: 5g/lit.
Heart muscle solids from infusion: 2g/lit.
Sheep blood, defibrinated