[Nitrogen requirements of Microtus rossiaemeridionalis].

Total nitrogen requirements in the small herbivorous rodent Microtus rossiaemeridionalis were studied. When provided with two kinds of standard laboratory food (about 20 and 0% digestible protein, respectively) ad libitum (cafeteria diet), the voles chose a diet of 14% protein. The total daily (with urine and faeces) nitrogen losses were, in this case, determined as 3.65 +/- 0. 60 mg N/g of body mass. When provided with a protein-free diet alone, the animals lost 0.90 +/- 0.05 mg N/g body mass per day, comprising about 3% of their body mass daily. It was proposed that the consumption of a low-fiber diet (about 4% in both kinds of food) could affect the gastrointestinal bacterial flora and, thus, lead to changes in the primarily herbivorous nitrogen metabolism.