Negative effects of acorns on the wood mouse Apodemus speciosus

Abstract

Antinutritional effects of acorns and tannic acid on the Japanese wood mouse Apodemus speciosus were examined in the laboratory. The first feeding experiment was conducted for 15 days using three types of diet: control diet (laboratory chow for mice), acorns of Quercus serrata (QS), and acorns of Q. mongolica var. grosseserrata (QM), which differ in tannin content (control, tannin free; QS, 2.7% tannic acid equivalent; QM, 8.5%). Six and one of eight mice died in the QM and QS groups, respectively, whereas all mice survived in good health in the control group. Body weight in the QM and QS groups decreased as much as 23.6% and 16.8% in the first 5 days, respectively, whereas that in the control group did not change significantly. Dry matter intake in the QM group was 50.0% and 38.7% less than that in the control and QS, respectively. Apparent dry matter digestibility was not different among the diets, but apparent nitrogen digestibility did differ between the two acorn groups (QM, −17.5%; QS, 12.0%). The logistic regression analyses revealed that the survival of mice was synergistically influenced by both dry matter intake and apparent nitrogen digestibility. In the second experiment, wood mice fed the tannin‐free formula diet, which is nutritionally matched to QS and QM acorns except for the tannin, did not suffer antinutritional effects, whereas mice fed the tannin‐supplemented formula diets suffered body weight loss and negative nitrogen digestibility. These results indicate that the tannins in acorns could cause serious damage to the wood mouse, which may rely on acorns as a usual diet. Plausible hypotheses explaining how the wood mice could overcome the deleterious effects of the acorns are discussed.

Does acclimation reduce the negative effects of acorn tannins in the wood mouseApodemus speciosus?

“…As described by Shimada and Saitoh (2003), one of the eight mice died in the QS group. In the present study, we conducted further analyses only on the individuals that survived until the end of the experiment in order to investigate the successive changes in the effects of acorn ingesting (for the control and QS groups, n = 8 and 7, respectively).…”

“…Wood mouse responses to acorn tannins 209 Shimada and Saitoh (2003) revealed that A. speciosus fed QS acorns suffered severe damage because of reduced dry matter intake and nitrogen digestibility. The present experiment, however, showed that the negative effects of the acorns decreased through continuous ingesting of acorns.…”

“…Tannins, a diverse group of water-soluble phenolics with high affinity for proteins, are widely distributed in various parts of plants, and have detrimental effects in herbivores: reduction in protein digestibility, damage to the gastrointestinal mucosa and epithelia, kidney or liver failure, intrinsic nitrogen loss, and dischanges in body weight and digestion. Some results from this experiment were already reported (Shimada and Saitoh 2003). The aims of the present study are to examine the effects of acclimation as a mechanism of mitigating the damage caused by acorn tannins and to examine whether A. speciosus can secrete PRPs in response to tannin intake.…”

Interspecific Differences in Tannin Intakes of Forest-Dwelling Rodents in the Wild Revealed by a new Method Using Fecal Proline Content

“…Feeding Experiments In order to examine the relationships between dietary tannin and fecal proline, we performed feeding experiments using a powdered formula diet that had a nutritional composition similar to that of acorns of Quercus crispula and Quercus serrata in terms of all major constituents except tannins (hereafter referred to as the basal diet; see details in the work of Shimada and Saitoh 2003). Tannic acid (Wako Pure Chemical Industries) was added to the basal diet at 1, 2, 3, or 4% on a dry weight basis (hereafter referred to as the 1-4% TA diets).…”

“…Tannins are a widespread group of PSMs that are broadly distributed in various plant parts (Waterman and Mole 1994). Ingesting tannins, a diverse group of watersoluble phenolics with high affinity for proteins, may have negative effects on herbivores, such as reduction in protein digestibility (Robbins et al 1987;Chung-MacCoubrey et al 1997;Shimada and Saitoh 2003), damage to the gastrointestinal mucosa and epithelium (Meiser et al 2000), or endogenous nitrogen loss (Shimada and Saitoh 2003).…”