Divergence in proportional fat intake in AKR/J and SWR/J mice endures across diet paradigms

These experiments were designed to test the hypothesis that the contrasting patterns of macronutrient selection described previously in AKR/J (fat pre ference) and SWR/J (carbohydrate preference) mice are not dependent on a si ngle diet paradigm. The effect of mouse strain on proportional fat intake w as tested in naive mice by presenting two-choice diets possessing a variety of physical, sensory, and nutritive properties. In three separate experime nts, AKR/J mice preferentially selected and consumed a higher proportion of energy from the high-fat diet than SWR/J mice. Specifically, this phenotyp ic difference was observed with 1) fat-protein vs. carbohydrate-protein die ts, independent of fat type (vegetable shortening or lard), 2) isocaloric, high- vs. low-fat liquid diet preparations, and 3) high- vs. low-fat powder ed-granular diets. These results confirm our previous observation of a high er proportional fat intake by AKR/J compared with SWR/J mice using the thre e-choice macronutrient selection diet and show that this strain difference generalizes across several diet paradigms. This strain difference is due la rgely to the robust and reliable fat preference of the AKR/J mice. In contr ast, macronutrient preference in SWR/J mice varied across paradigms, sugges ting a differential response by this strain to some orosensory or postinges tive factor(s).