Effects of diet quality on energy budgets and thermogenesis in Brandt's voles.

Food quality and availability play an important role in an animal's life history. The aim of this study was to examine the effect of diet quality [high-fiber diet (HF) or low-fiber diet (LF)] on energy budgets and thermogenesis in Brandt's voles (Lasiopodomys (Microtus) brandtii). Dry matter intake and gross energy intake increased and digestibility decreased in HF voles compared with LF voles, while the digestible energy intake was similar for both HF and LF voles. Nonshivering thermogenesis (NST) decreased in HF voles, while LF voles kept stable; no significant differences were detected in basal metabolic rate (BMR), BAT uncoupling protein 1 (UCP1) content and the levels of serum thyroid hormones (T3 and T4) between HF and LF voles. Although there were no differences in body fat content and serum leptin concentrations between HF and LF voles, serum leptin concentrations in HF voles were reduced to nearly half as those seen in LF voles after 4-weeks acclimation. These results support the hypothesis that Brandt's voles can compensate the poor quality diet physiologically by the means of increasing food intake and decreasing thermogenesis.