Animals regularly consume naturally occurring plant compounds that can be toxic. Tannins are the most abundant and widespread of these compounds, which are ultimately metabolized by the liver. Recent work has revealed that ambient temperature can alter liver function and clearance rate of some toxins by rodents, but little is known about the nutritional and physiological consequences of consuming tannins at different ambient temperatures.
The Japanese wood mouse (Apodemus speciosus) has an important ecological role in Japanese forests, as they hoard and consume acorns. Despite the high concentration of tannins in some species of acorns and the proven toxic effects of tannins on wood mice in captivity, they can survive for several months in the wild on an acorn diet.
We fed acorns (6.2% tannin DW) to 31 A. speciosus housed at either 20°C or 10°C. Acorn consumption improved the liver function of wood mice at 10°C, but reduced liver function at 20°C, revealing a complex relationship between ambient temperature and tannin intake on liver function. Furthermore, mice with faster liver function exhibited greater protein digestibility on an acorn-only diet. These results suggest that environmental temperature may play a significant role in the tolerance of wild A. speciosus to tannins.