Rabbit Serum is obtained and pooled from donor populations. It is often used in combination with BSA (bovine serum albumin) as a blocking agent in immunocytochemistry and immunohistochemistry applications. Rabbit serum is collected from animals typically six months old or younger.Rabbit Serum is obtained and pooled from donor populations. It is often used in combination with BSA (bovine serum albumin) as a blocking agent in immunocytochemistry and immunohistochemistry applications. Rabbit serum is collected from animals typically six months old or younger.