Forage Resources, Nutrition, and Food Supply of Free-Grazing Camels (Camelus bactrianus) in a Pasture within the Natural Steppe Zone

摘要

This paper reports the results of investigation on the food of free-grazing Bactrian camels in a forb-grass steppe pasture, including anthropogenically disturbed areas with dominance of ruderal annuals. We identified the composition of consumed plants using a microhistological analysis of the feces; the digestibility coefficient based on inert (indigestible) silicon contained both in the diet and feces; the quantity of the forage consumed based on the mass of the feces and the digestibility coefficient; and the energy balance based on interrelations between the actual consumption and the existing requirement norms of camels and wild ungulates in energy. In spring, camels mainly consume graminoids (Stipa sp. and Festuca valesiaca), switching to forbs, largely ruderal annuals, in summer and autumn. The forage digestibility is low in spring (56%), increasing to 69-70% in summer and autumn. Low daily consumption rates of dry forage mass in winter and spring (8-9 kg) are changed to high in summer and autumn (20-26 kg), this reflecting the animals' winter hypophagy. The amount of energy received during the warm season (1.2-1.8 MJ/kg W-0.75) considerably exceeds the requirements, thus explaining the ability of camels to accumulate a safety store of fat in the humps.