Histamine in egg yolk: heat resistance and relation to production status

1. The presence of histamine in egg yolk, its losses during storage, incubation and heating, and its relationship to cage density stress and the egg production status of hens are described. 2. A significant (P less than 0.05) reduction in the histamine concentration of egg yolk was noted after incubating or heating egg yolks or on storage eggs. 3. Histamine concentration was greater in the yolks of high egg producing hens. 4. The concentrations of histamine in egg yolks did not change significantly (P less than 0.05) on keeping the hens individually in a cage, pairing them in the same size cage or after separating them again to individual cages.