A challenge for the future Bio-food lover
We do not hear all that much about Indian research, although India’s successful Mangalayaan Mars probe did cause worldwide admiration. There are in fact hundreds of thousands of good scientists there (and even more not so good ones) and it can be very interesting to find out what some of them are working on. Take for instance Dr Shetty and colleagues of Mangalore University. Their work caught my attention quite a few years ago: it dealt with the composition of pigeon milk.
Although in most birds partly-digested food is fed to the offspring by the parental birds, pigeons and doves are an exception. These birds secrete a nutritive, cheese-like, epithelial mucus, commonly known as crop-milk, which is very rich in protein and fats and consists of 25% solids and 75% water. During the first four to six days of their lives pigeon babies, known as “squabs”, are being fed exclusively this health and growth-promoting milky secretion. The parent birds stop eating a few days before the chicks hatch so that the crops of the parents of the parents can secrete the milk and do not contain grain at that time, which the squabs would not be able to digest. To feed the young, both parents, male as well as female, regurgitate crop milk and thrust it down the throat of the nestlings. After a week of this baby nutrition, the squabs are gradually weaned by being fed solids that are first softened in the crops of the parent birds.
Pigeon milk is a fantastically wholesome food and squabs reared entirely on this diet show a phenomenal postnatal growth rate. It is, however, not produced in great quantities by the parent birds, which is thought to be the reason why usually only two eggs are laid. Chemically pigeon milk, like the milk of cows, sheep, goats and humans is a rich source of proteins and lipids, but contains few vitamins and very small amounts of carbohydrates. The Indian study showed that in terms of its mineral content, especially when it comes to trace elements like iron, zinc, manganese and copper, pigeon milk is richer than human and all the other milk types we consume. Interestingly, the discovery of the actions of the hormone “prolactin”, which controls milk production in humans and other mammals, owes much to the pigeon, for because of the close parallelism to mammalian lactation much of the early research on the physiology of prolactin was intimately bound up with the pigeon’s crop-sac response, allowing scientists to measure the effectiveness of this milk-inducing hormone.
So, in summary, the humble pigeon, peace symbol par excellence and used in wars as “a living drone” before present-day drones were available, long celebrated for its homing ability, possesses yet another remarkable property: its milk. Under the control of the same hormone that acts on the bodies of female mammals, it appears to be more nutritious than that of human mothers and, most of all, it can be produced by fathers as well! So, how long will it take until a smart business person starts marketing it and we can buy it in the shop?
© Dr V.B. Meyer-Rochow and http://www.bioforthebiobuff.wordpress.com, 2018.
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