Cold temperature improves tannin tolerance in a granivorous rodent

Area of Science:

• Ecology
• Animal Physiology
• Biochemistry

Background:

• Mammalian herbivores rely on detoxifying plant secondary metabolites (PSM) for foraging.
• Ambient temperature affects liver function and PSM toxicity, but its impact on tannin tolerance is unknown.
• Tannins are a ubiquitous class of PSM with significant implications for herbivore diets.

Purpose of the Study:

• To investigate the combined effects of ambient temperature and tannin intake on liver function.
• To determine the impact of temperature on tannin tolerance in wild Japanese wood mice (Apodemus speciosus).
• To elucidate the physiological and nutritional consequences of consuming tannins at different temperatures.

Main Methods:

• Mice were acclimated to either 10°C or 20°C.
• Mice were subsequently fed an acorn diet (6.2% tannin DW).
• Liver function was assessed by measuring hypnotic agent clearance time before and after acorn acclimation.
• Tannin tolerance was evaluated through a 5-day acorn-only feeding trial.

Main Results:

• Acclimation to acorns significantly altered liver function, with effects dependent on ambient temperature.
• Liver function improved at 10°C but decreased at 20°C following acorn consumption.
• Faster hypnotic agent clearance (indicating better liver function) correlated with higher protein digestibility on an acorn diet.
• This suggests improved tannin tolerance at lower temperatures.

Conclusions:

• Environmental temperature plays a crucial role in modulating tannin tolerance in Apodemus speciosus.
• Cold-induced tannin tolerance may explain seasonal feeding behaviors and population dynamics of mammalian herbivores.
• Findings offer insights into herbivore responses to climate change and dietary shifts in tannin content.