Our donkey serum is collected from pathogen-free, donor-herd animals. All serums are 0.2uM filtered to guarantee no microbial growth and low endotoxin levels. Donkey serum contains high amounts of macromolecules, nutrients, enzymes, and hormones that can be used for enzyme assays as well as cell culture supplements. The most common use of donkey serum is as a blocking buffer for immuno-assays such as immunohistochemistry, immunoblotting, and immunofluorescence. Heat-inactivated serum can be made upon request.