Misplaced Pages

Crop milk

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.

This is an old revision of this page, as edited by 188.102.24.82 (talk) at 09:56, 8 July 2021 (Removed the word “also” which (confusingly) implied that 2 hormones control the secretion of crop milk whereas only a single hormone is mentioned). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

Revision as of 09:56, 8 July 2021 by 188.102.24.82 (talk) (Removed the word “also” which (confusingly) implied that 2 hormones control the secretion of crop milk whereas only a single hormone is mentioned)(diff) ← Previous revision | Latest revision (diff) | Newer revision → (diff) secretion used by some birds to feed their young
A greater flamingo chick in Zoo Basel is fed crop milk

Crop milk is a secretion from the lining of the crop of parent birds that is regurgitated to young birds. It is found among all pigeons and doves where it is referred to as pigeon milk. An analog to crop milk is also secreted from the esophagus of flamingos and the male emperor penguin.

Crop milk bears little physical resemblance to mammalian milk, the former being a semi-solid substance somewhat like pale yellow cottage cheese. It is extremely high in protein and fat, containing higher levels than cow or human milk. It has also been shown to contain anti-oxidants and immune-enhancing factors. Like mammalian milk, crop milk contains IgA antibodies. It also contains some bacteria. Unlike mammalian milk, which is an emulsion, pigeon crop milk consists of a suspension of protein-rich and fat-rich cells that proliferate and detach from the lining of the crop. Lactation in birds is controlled by prolactin, which is the same hormone that causes lactation in mammals.

Pigeon's milk begins to be produced a couple of days before the eggs are due to hatch. The parents may cease to eat at this point in order to be able to provide the squabs (baby pigeons and doves) with milk uncontaminated by seeds, which the very young squabs would be unable to digest. The baby squabs are fed on pure crop milk for the first week or so of life. After this the parents begin to introduce a proportion of adult food, softened by spending time in the moist conditions of the adult crop, into the mix fed to the squabs, until by the end of the second week they are being fed entirely on softened adult food.

Pigeons normally lay two eggs. If one egg fails to hatch, the surviving squab gets the advantage of a supply of crop milk sufficient for two squabs and grows at a significantly faster rate. Research suggests that a pair of breeding pigeons cannot produce enough crop milk to feed three squabs adequately, which explains why clutches are limited to two.

References

  1. Levi, Wendell (1977). The Pigeon. Sumter, S.C.: Levi Publishing Co, Inc. ISBN 0-85390-013-2.
  2. Silver, Rae (1984). "Prolactin and Parenting in the Pigeon Family" (PDF). The Journal of Experimental Zoology. 232 (3): 617–625. doi:10.1002/jez.1402320330. PMID 6394702. Archived from the original on 2016-09-13.{{cite journal}}: CS1 maint: bot: original URL status unknown (link)
  3. Eraud, C., Dorie, A., Jacquet, A. and Faivre, B. (2008). "The crop milk: a potential new route for carotenoid-mediated parental effects". Journal of Avian Biology. 39 (2): 247–251. doi:10.1111/j.0908-8857.2008.04053.x.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  4. Ehrlich, Paul R.; Dobkin, David S. and Wheye, Darryl (1988) Bird Milk. stanford.edu
  5. "Mysteries of pigeon milk explained" Archived 2011-09-24 at the Wayback Machine Retrieved September 22, 2011
  6. ^ Gillespie, M. J.; Stanley, D.; Chen, H.; Donald, J. A.; Nicholas, K. R.; Moore, R. J.; Crowley, T. M. (2012). Salmon, Henri (ed.). "Functional Similarities between Pigeon 'Milk' and Mammalian Milk: Induction of Immune Gene Expression and Modification of the Microbiota". PLoS ONE. 7 (10): e48363. doi:10.1371/journal.pone.0048363. PMC 3482181. PMID 23110233.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  7. Gillespie, M. J.; Haring, V. R.; McColl, K. A.; Monaghan, P.; Donald, J. A.; Nicholas, K. R.; Moore, R. J.; Crowley, T. M. (2011). "Histological and global gene expression analysis of the 'lactating' pigeon crop". BMC Genomics. 12: 452. doi:10.1186/1471-2164-12-452. PMC 3191541. PMID 21929790.{{cite journal}}: CS1 maint: unflagged free DOI (link)
  8. Vandeputte-Poma, J.; van Grembergen, G. (1967). "L'evolution postembryonnaire du poids du pigeon domestique". Zeitschrift für vergleichende Physiologie. 54 (3): 423–425. doi:10.1007/BF00298228.
  9. Blockstein, David E. (1989). "Crop milk and clutch size in mourning doves". The Wilson Bulletin. 101 (1): 11–25. JSTOR 4162684. The fact that none of the nearly 300 species of Columbiformes has a clutch size larger than two eggs suggests that there is limited plasticity in crop-milk production.

External links

Category: