Cholecalciferol supplementation alters gut function and improves digestibility in an underground inhabitant, the naked mole rat ( Heterocephulus gluber ), when fed on a carrot diet

Abstract

Naked mole rats ( Heterocephalus glaber ) lead a strictly subterranean existence and appear to be naturally deficient in cholecalciferol (D 3 ). Oral supplementation with D 3 (D s ) led to a 1.8-fold increase in food intake and the associated enlargement (1.4-fold) of the caecum. The effect of D s , and the concomitant increase in food intake, on caecal fermentation efficiency when animals were fed on a carrotbased diet was determined by measuring the rate of both gas production and short-chain fatty acid (SCFA) production. Microbial-controlled fermentation processes in the caecum were enhanced with D s when compared with animals not receiving a D 3 supplement (D n ). Both the rates of gas production (D n 10.76 (SE 0.77), D s 15.20 (SE 1.77) ml/g dry matter (DM) per h) and SCFA production (D n 463.0 (SE 33.7), D s 684.3 (SE 74.8) μ mol/g DM per h) increased more than 1.4-fold per g DM caecal substrate. These factors contributed to the higher digestibility of the food in D s animals. The larger quantity of energy available to D 3 -replete naked mole rats was not used in anabolic processes, for these animals maintained mass. These findings suggest that metabolic rate in D 3 -replete animals was elevated. Thus, despite improved gut function, D 3 -replete animals may be disadvantaged by their higher energy and food requirements in their natural milieu.