Seasonal variations of digestive tract length and weight of Niviventer confucianus in Dongting Lake region

The study showed that there existed obvious seasonal variations in the digestive tract length and weight of Niviventer confucianus in Dongting lake region. The fresh weight of digestive tract with contents and the fresh and dry weights of the tract without contents were higher in winter and spring than in summer and autumn. As for different organs of the tract, stomach showed significant seasonal variation of its length, being the shortest in winter and longer in summer and autumn, which was the response of N. confucianus to take more food to fit the energy needs for reproduction and to meet the abundant food in summer and autumn. The length, fresh weight with and without contents, and dry weight without contents of other organs (small intestine, caecum and large intestine) were larger in winter and spring than in summer and autumn, an adaptive response to the low temperature and food deficiency in winter and spring. It was suggested that N. confucianus had strong capability in adjusting its gastrointestinal volume and size to adapt to the seasonal changes of ambient temperature and food resources.