Pigeon And Dove Crop Milk

Crop milk is produced by a sloughing of fluid-filled cells from the lining of the crop. A hormone called Prolactin stimulates the growth and development of specialized epithelial cells within the crop. 1, 7 Prolactin levels in the adult begin to increase during the last half of egg incubation and remain high until 4 days after hatching. 8

The milk the crop produces is extremely nutritious. Research conducted on the use of crop milk for other species, including mammals, demonstrated increased weight gain. 3 Crop milk also contains a growth factor that is higher than that of many mammals. The level of growth factor in the milk stays fairly constant for the first 5 days. 5 The nutrient value of the milk along with the high growth factor activity appear to be the contributing factors at the phenomenal growth of the young, which increase their body weight 22-fold within the first 3 weeks after hatching. 11

The adult's crop microflora contains Lactobacilli, streptococci and coliforms. 6. Lactobacillus agilis, (a bacteria also found in sewage), was the dominant in one study of pigeon crops. 10 Some of these "good" bacteria are transferred to the young during feeding. Crop milk also contains antibodies that help the young's resistance to certain infections. 4Pigeon milk is richer than adult pigeon feed in its mineral content. The Ca:P ratio of pigeon milk increases from 0.3 to 1.1 in the first five days. 12 Carbohydrate levels in crop milk are in the range of .9-1.5%. Dramatic changes occur in the level of sugars from day 1 of milk secretion to day 5 (+67%).2

By volume, crop milk is 9-13% protein, 9-11% fat, .9-1.5% carbohydrate, .8-1.1% ash and having a kCal content of 5.6-6.8%. Blood triglycerides are thought to be used for the formation of crop milk lipid. 9 The composition of crop milk appears to change dramatically during the first 5 days of secretion.

Crop milk is the sole source of nutrition for approximately two weeks. Gradually adult foods are introduced along with the crop milk.

Comparison at 75% moisture:

crop milk (11% protein 10% fat)44% protein40% fat
large raw egg51.6% protein40% fat
Exact24.4% protein8.9% fat

1Horseman ND, Buntin JD. ,Regulation of pigeon cropmilk secretion and parental behaviors by prolactin., Annu Rev Nutr 1995;15:213-38
2Shetty S, Salimath PV, Hegde SN., Carbohydrates of pigeon milk and their changes in the first week of secretion., Arch Int Physiol Biochim Biophys 1994 Sep-Oct;102(5):277-80
3Bharathi L, Shenoy KB, Hegde SN., In vivo and in vitro growth-stimulatory effects of pigeon milk., Comp Biochem Physiol Comp Physiol 1994 Jun-Jul;108(2-3):451-9
4Kocianova E, Rehacek J, Lisak V., Transmission of antibodies to Chlamydia psittaci and Coxiella burnetii through eggs and "crop milk" in pigeons., Eur J Epidemiol 1993 Mar;9(2):209-12
5Bharathi L, Shenoy KB, Mojamdar M, Hegde SN., Studies on the growth-stimulatory activity of pigeon milk--comparison and synergistic effects with serum., J Comp Physiol [B] 1993;163(4):332-6
6Shetty S, Sridhar KR, Shenoy KB, Hegde SN., Observations on bacteria associated with pigeon crop., Folia Microbiol (Praha) 1990;35(3):240-4
7Anderson TR, Pitts DS, Nicoll CS., Prolactin's mitogenic action on the pigeon crop-sac mucosal epithelium involves direct and indirect mechanisms., Gen Comp Endocrinol 1984 May;54(2):236-46
8Goldsmith AR, Edwards C, Koprucu M, Silver R., Concentrations of prolactin and luteinizing hormone in plasma of doves in relation to incubation and development of the crop gland., J Endocrinol 1981 Sep;90(3):437-43
9Garrison MM, Scow RO., Effect of prolactin on lipoprotein lipase in crop sac and adipose tissue of pigeons., Am J Physiol 1975 May;228(5):1542-4
10Baele, M., Devriese, L.A., Haesebrouck, F., Lactobacillus agilis is an important component of the pigeon crop flora, JOURNAL OF APPLIED MICROBIOLOGY , 91(3):488-491 2001
11Shetty, S., Bharathi, L., Shenoy, K. B., Hegde, S. N., Biochemical properties of pigeon milk and its effect on growth, JOURNAL OF COMPARATIVE PHYSIOLOGY -- B , 162(7):632 1992