Effect of Corncob bedding on feed conversion efficiency in a high-fat diet-induced prediabetic model in C57Bl/6J mice

Abstract

Laboratory facilities use many varieties of contact bedding, including wood chips, paper products, and corncob, each with its own advantages and disadvantages. Corncob bedding, for example, is often used because of its high absorbency, ability to minimize detectable ammonia, and low cost. However, observations that mice eat the corncob lead to concerns that its use can interfere with dietary studies. We evaluated the effect of corncob bedding on feed conversion (change in body weight relative to the apparent number of kcal consumed over 7 d) in mice. Four groups of mice (6 to 12 per group) were housed in an individually ventilated caging system: (1) low-fat diet housed on recycled paper bedding, (2) low-fat diet housed on corncob bedding, (3) high-fat diet housed on recycled paper bedding, and (4) high-fat diet housed on corncob bedding. After 4 wk of the high-fat diet, feed conversion and percentage body weight change both were lower in corncob-bedded mice compared with paper-bedded mice. Low-fat-fed mice on corncob bedding versus paper bedding did not show statistically significant differences in feed conversion or change in percentage body weight. Average apparent daily feed consumption did not differ among the 4 groups. In conclusion, these data suggest that corncob bedding reduces the efficiency of feed conversion in mice fed a high-fat diet and that other bedding choices should be favored in these models.

Figure 1.

Feed conversion of mice housed on recycled paper bedding and fed a low-fat diet (P + LF) and those housed on corncob bedding and fed a low-fat diet (CC + LF) did not differ (P = 0.081). However, feed conversion of mice housed on recycled paper bedding and fed a high-fat diet (P + HF) differed significantly (‡, P < 0.0001) from that of mice housed on corncob bedding and fed a high-fat diet (CC + HF).

Figure 2.

Mean body weights of mice housed on recycled paper bedding and fed a high-fat diet (P + HF) and those housed on corncob bedding and fed a high-fat diet (CC + HF) differed significantly at 4 wk (†, P = 0.0148) and 5 wk (‡, P = 0.0023) after the start of the diet. In contrast, body weight did not differ between mice housed on recycled paper bedding and fed a low-fat diet (P + LF) and those housed on corncob bedding and fed a low-fat diet (CC+LF) at either 4 wk (P = 0.454) or 5 wk (P = 0.376).

Figure 3.

Average apparent daily feed consumption for the 5-wk period after initiating high-fat feed did not differ between either mice housed on recycled paper bedding and fed a low-fat diet (P + LF) and those housed on corncob bedding and fed a low-fat diet (CC + LF; P = 0.088) or between mice housed on recycled paper bedding and fed a high-fat diet (P + HF) and those housed on corncob bedding and fed a high-fat diet (CC + HF; P = 0.379).