Feeding Laboratory Mice: Comparing a Standard Versus a Purified Diet – Marked Effects on Digestive Physiology

Diet composition and processing have a major impact on its utilisation by the animal, as is known from farm and pet animal species. This includes effects on energy and nutrient digestibility, the intermediary metabolism, and the intestinal microbiome, with all the resulting impacts. For laboratory animals, data is scarce on influencing factors on diet digestibility. In experiments using special diets, either standard diets are used for the control group, or purified control diets. The aim of the present study was to compare a standard diet and a purified control diet (both pelleted) fed ad libitum to C57BL/6J mice and to investigate the potential effect on body weight development, feed conversion, energy and nutrient digestibility and indicators of intestinal fermentation (pH, short-chain fatty acids). Thus, 21 mice each were fed the standard diet (STD) and the purified diet (PD). Results showed a significantly higher apparent digestibility of gross energy and the crude nutrients in group PD (p < 0.001). The weight of the filled cecum and colon was significantly lower in group PD than STD (p < 0.001; p < 0.01). The pH of ingesta was significantly higher in stomach, cecum and colon of group PD (p < 0.0001), likely influenced by the significantly lower concentration of total short-chain fatty acids measures in cecum and colon of PD mice. The high apparent digestibility of the PD implied a lower influx of fermentable substrate into the hindgut, resulting in lower concentrations of microbial metabolites and altered pH milieu.