Carbohydrates of pigeon milk and their changes in the first week of secretion.

Abstract

The carbohydrate content of pigeon crop secretion called pigeon milk (PM) was in the range of 0.9-1.5%. Sugars of trichloroacetic acid soluble (TCA-S) fraction increased by 67% between day-1 and day-5 of secretion while those of TCA- insoluble (TCA-P) fraction remained fairly constant. Sialic acids constituted 5-9% of carbohydrates. The proportion of lipid- and protein-bound sialic acids was 51% and 31% respectively; the former increased from 41% to 68% between day-1 and day-5 whereas the latter decreased from 45% to 21% during the corresponding period. Some of the sugars of PM were fucose (40%), glucosamine (31%), galactose (12%), mannose (9%) and glucose (8%). The free sugars whose content was very low (0.05%) included fucose, mannose, glucose and some unidentified oligosaccharides. The proportion of lipid- and protein-bound sugars was 31% and 63% respectively; the former decreased by 7% from day-1 to day-5 while the latter increased by 11% during the same period. Gel chromatography of PM confirmed the presence of sialic acids and glucosamine; the latter existed both in free and bound form. The nature of changes in the carbohydrate composition of PM in the first week of secretion was more quantitative than qualitative.