I. O. Lykova, M. F. Kovtun, L. P. Kharchenko and R. I. Kratenko
The plasticity of the digestive system (DS) of birds allows them to use a wide range of feeds, which is especially important for migratory birds. Some fatty acids (FAs) included in the spectrum of polyunsaturated FAs (PUFAs) are not synthesized in the bird organism, and are supplied only with food. They determine the level of unsaturation of lipids, and are essential for the organism. Among other important functions of these FAs are energy: they affect the energy metabolism of muscle cells. This is what determines the demands of migratory birds to the fodder base of migration stops. The largest number of general lipids among investigated species of invertebrates living in the Azov-Black Sea region ponds is found in the organisms N. zonata, A. salina, H. diversicolor, I. baltica (4.6–4.0%). The highest content of PUFAs was revealed to be present in the lipids of mollusks H. acuta and Th. astrachanicus: 32.87–35.73 % of the total amount of FAs. The content of PUFAs in the organism of Chironomis depends on the degree of water salinity. The unsaturation coefficient of FAs (K1) is revealed to be the highest in Mollusk lipids (H. acuta — 1.361; Th. astrachanicus — 1.610) and some Polychaeta. These types of invertebrates are the main source of intake of essential PUFAs by the organism of the waders at migratory stops in the Azov-Black Sea region.