Nitrogen fixation: A new phenomenon in rodent nutrition

We have conducted a series of experiments in order to test hypothesis about the possible use of nitrogen fixation by small phytophagous mammals as a w ay to supplement their nitrogen balance. Two groups of red voles Clethriono mys rutilis were kept on rations with different protein nitrogen content. T hree days later, the rate of nitrogen fixation was determined in different regions of the digestive tract. Nitrogen-fixing activity has been detected in the GI tract of all studied voles, specifically in those regions, where symbiocenoses were present; it was particularly high in animals of the expe rimental group under the conditions of dietary nitrogen limitation. A mixed culture of bacteria capable of nitrogen fixation has been isolated from th e digestive tract of red voles.