Chicken antibodies are isolated from egg yolk of eggs from chickens immunised by the antigen of your choice.
The production process does not involve any blood sampling or sacrificing of animals. An egg-laying chicken lays 5-6 eggs per week, yielding a large amount of antibodies that otherwise would need several animals or a huge in vitro production capacity to obtain. Chickens are not mammals. They are therefore genetically very far from homo sapiens and other mammals. Due to this genetic distance, chickens usually have a stronger immunologic response to human antigens than mice, rabbits, sheep and other mammals. Chickens often recognize a large part of the antigen as «foreign». They are therefore often used to obtain antibodies to human structures where mice and rabbits tend to fail. Rheumatoid factors of mammalian sera often react with mammalian antibodies, causing false positive results when antibodies of mammalian origin are used. Rheumatoid factors do not react with chicken antibodies.