Microbial nitrogen fixation in the gastro-intestinal tract of Kalmykia gerbils (<Emphasis Type="Italic">M. tamariscinus</Emphasis> and <Emphasis Type="Italic">Meriones meridianus</Emphasis>)

The nitrogen-fixing activity, nitrogen (N) and carbon (C) contents, and the number of microorganisms in the forestomach, cecum, and colon were detected in two gerbil species, granivorous Meriones meridianus and M. tamariscinus, which consume a large amount of green parts of the plants. M. meridianus had higher levels of nitrogen-fixation activity in all investigated parts of the gastro-intestinal tract compared with M. tamariscinus. The highest levels were detected in the colon of M. meridianus. The C/N ratios in the forestomach of M. tamariscinus were higher than in M. meridianus, which is consistent with the greater role of the green parts of plants in its diet. A gradual increase in the nitrogen content from the forestomach to the colon of M. tamariscinus was noted. The amount of microorganisms in the forestomach and intestine of the studied gerbil species was similar.