食物质量对两种啮齿动物的消化对策和能量代谢的影响

食物质量对动物的消化策略和能量代谢的影响是生理和营养生态学研究的核心问题。通过实验测定食物质量对内蒙古草原两种小型兽的消化效率和代谢特征等的影响，运用现代食物标记技术测定食物在消化道中的滞留时间，确定动物的消化道形态和功能对食物质量的反应，确定动物是否具有结肠分离机制和食粪行为，从而刻画两种动物的消化策略和食物质量与能量代谢的关系。

We used two markers (Co-EDTA for solutes and Cr-mordanted cell walls for particles) to measure differential passage rates of digesta fractions in order to understand their digestive strategies and test for the presence of a colonic separation mechanism (CSM) for Mongolian gerbils (Meriones unguiculatus) and Brandt's voles (Microtus brandti) which offered pelleted diets of low (14% and 25% neutral-detergent fiber for gerbil and vole, respectively) and high (27% for gerbil and 38% for vole) fiber content. For Mongolian gerbils, the mean retention time (MRT) of the particle marker was significantly greater than that of the solute marker on the low fiber but not the high fiber diet; the solute/particle differential retention ratio was 0.62 on the low fiber diet and 0.90 on the high fiber diet. Thus there was no evidence for selective retention of the solute marker on either diet. The MRT of the particle marker was significantly lower on the high fiber diet, and in the same direction as the MRT of the solute marker. These results suggest that the granivorous Mongolian gerbil has no colonic separation mechanism (CSM). For Brandt's voles, total tract mean retention time (MRT) of a solute marker was significantly greater than that of a particle marker on the lower fiber diet, and in the same direction on the higher fiber diet. The ratio of solute to particle MRTs (the solute/particle differential retention ratio) was 1.45 on the lower fiber diet and 1.19 on the higher fiber diet. There were no significant differences in marker MRTs between diets. Thus the results showed the elective digesta retention in Brandt's voles.