What is pigeon milk and how can be it produced?

Pigeon milk is not milk in the traditional sense of dairy or soy milk. No species of birds provide milk for their young.

Some birds such as pigeons, doves, male emperors penguins and flamingoes are fed on special secretions from the parent birds' crop which are the result of regurgitated food. These secretions are sometimes called crop milk, but they are not milk in the true sense of the Word. However, they are rich in nutrients and fats. The production of the milk is controlled by prolactin, which is the same hormone that begins milk production in mammals, and is released from the pituitary gland. The lining of the crop sloughs off fluid-filled cells containing more fat and protein than cows' milk, as well as minerals and antibodies, forming a nutritious milk-like substance known as crop milk. Both males and females produce this liquid.

Australian researchers have recently discovered that pigeon milk offers similar nutrients to that found in mammals' milk. During the breeding season, instead of storing food, the pigeons' crop is stimulated by hormones to take on a 'lactating' role. Interestingly, in a study where pigeon milk was fed to chickens, the growth rate of the baby chicks increased by 38%.