Intake and preference for dried bonito dashi in male Sprague-Dawley rats and C57BL/6 N mice

Dried bonito dashi is a traditional Japanese fish broth that enhances palatability of various dishes due to its specific flavor. The present study examined influences of dietary fat levels (10% vs. 45% fat), presentation order of dried bonito dashi (ascending vs. descending concentrations), and prior experience with dashi on subsequent dashi intake and preference using two-bottle choice tests in two rodent strains, Sprague-Dawley (SD) rats and C57BL/6 N (B6N) mice. In the ascending concentration tests, SD rats on a low fat diet preferred 10-100% dashi to water, whereas B6N mice showed a blunted preference for dashi. Consumption of a high fat diet reduced dashi preference in SD rats. The B6N mice on the high fat diet never preferred dashi at any concentration. In the descending concentration tests, SD rats on the low fat diet preferred dashi over a wide range (0.03-100% dashi). The B6N mice showed a trend similar to that of SD rats. Ingestion of the high fat diet in both strains reduced dashi preference in the descending concentration tests. However, introduction of the high fat diet to dashi experienced rats maintained on the low fat diet, reduced neither dashi intake nor dashi preference. Dashi intake affected neither high fat diet intake, caloric intake, nor preference for high fat diet. These results suggest that preference for dried bonito dashi is influenced at least by 1) dietary fat levels, 2) presentation order of dashi, and 3) prior experience with dashi.