Body weights of C3H/HeN mice fed semipurified or commercial diets of different fat content

Abstract

Oncology studies often require specially formulated diets to be fed to laboratory animals. To determine the effect of dietary fat on body weight, C3H/HeN mice were carefully assigned by weight into three groups. The first group was fed a high‐fat semipurified diet (23 % fat by weight) from 21 to 73 days of age then returned to a low‐fat semipurified diet (5% fat by weight). A second group was fed the low‐fat diet from 21 to 73 days of age, then the high‐fat diet until 129 days of age, then returned to the low‐fat diet. A final group was fed a 4.5% fat commercial diet for the entire 193‐day study. The results showed that the mice fed the semipurified diets did not differ significantly from each other in weight over the course of the study but did differ significantly between 21 and 73 days of age, possibly from a taste preference for the high‐fat diet. Mice fed the commercial diet always weighed significantly less. It was estimated that mice fed the commercial diet consumed more food and were less efficient in their food utilization. Mice should be carefully assigned, by weight, into experimental groups, and all groups, including untreated controls, should be fed the same type of diet.