All mammalian milk contains water, sugar, fat, vitamins, and protein with the variation within and between species and individuals differing mainly in the amount of these components.[1] Other than the variation in quantity of these components, not a lot is known about bio-active or immune-modulating factors in many mammalian species. However, in comparison to other mammalian milk, human milk has the most oligosaccharide diversity.[2]
Ruminant mothers do not transfer immunity to their infants during pregnancy, which makes milk the first introduction to maternal immunity calves receive.[3]Bovine milk contains both immunoglobulins A and G, but in contrast to human milk where IgA is the most abundant, IgG is more abundant.[4]Secretory Component, IgM, both anti-inflammatory and inflammatory cytokines, and other proteins with antimicrobial functions are also present in bovine milk.[3]
Human milk immunity is the protection provided to the immune system of an infant via the biologically active components in human milk. Human milk was previously thought to only provide passive immunity primarily through Secretory IgA, but advances in technology have led to the identification of various immune-modulating components.[5][6][7] Human milk constituents provide nutrition and protect the immunologically naive infant as well as regulate the infant's own immune development and growth.[8]
Crop milk is a secretion from the crop of a bird that is regurgitated to feed their offspring.[12] Birds that produce this secretion include pigeons, flamingos, emperor penguins, and doves.[13] Pigeon milk contains some immune-modulating factors such as microbes and IgA, as well as other components with similar biological activities to mammalian milk including pigeon growth factor, and transferrin.[14]
^Power, Michael L.; Schulkin, Jay (2016). The Biology of Lactation Milk. Baltimore, Maryland: Johns Hopkins University Press. p. 4. ISBN978-1-4214-2043-1.
^Martin, M.A.; Sela, D.A. (2013). "Infant Gut Microbiota: Developmental Influences and Health Outcomes". In Clancy, KB; Hinde, K; Rutherford, JN (eds.). Building Babies. New York: Springer. pp. 233–256. doi:10.1007/978-1-4614-4060-4_11. ISBN9781461440598.
^ abStelwagen K, Carpenter E, Haigh B, Hodgkinson A, Wheeler TT (April 2009). "Immune components of bovine colostrum and milk". Journal of Animal Science. 87 (13 Suppl): 3–9. doi:10.2527/jas.2008-1377. PMID18952725. S2CID43829526.
^Cakebread JA, Humphrey R, Hodgkinson AJ (August 2015). "Immunoglobulin A in Bovine Milk: A Potential Functional Food?". Journal of Agricultural and Food Chemistry. 63 (33): 7311–6. doi:10.1021/acs.jafc.5b01836. PMID26165692.
^ abMiller E (2018). "Beyond Passive Immunity Breastfeeding, milk and collaborative mother-infant immune systems". In Tomori C, Palmquist AE, Quinn EA (eds.). Breastfeeding New Anthropological Approaches. New York: Routledge. pp. 26–36. ISBN978-1-138-50287-1.
^Martin MA, Sela DA (2013). "Infant Gut Microbiota: Developmental Influences and Health Outcomes". In Clancy KB, Hinde K, Rutherford JN (eds.). Building Babies. New York: Springer. pp. 233–256. doi:10.1007/978-1-4614-4060-4_11. ISBN9781461440598.
^Power, Michael L.; Schulkin, Jay (2016). "Feeding Offspring". The Biology of Lactation Milk. Baltimore, Maryland: Johns Hopkins University Press. pp. 26–27. ISBN978-1-4214-2042-4.