Taste, intake rate, and food choice in rats

The contribution of taste to the food choices of foraging rats was examined. Rats in a laboratory foraging paradigm searched for sequential opportunities to eat at two feeders containing chow-based food pellets that were plain or flavored with saccharin or citric acid. Pellets cost the same number of bar presses at both feeders. Saccharin adulteration had no effect on intake parameters. Citric-acid-flavored pellets were eaten more slowly and in smaller meals. If there was no alternative food, daily intake was slightly reduced. When the alternative food was plain, fewer meals and fewer pellets were taken of the citric-acid-flavored than plain pellets. When we gradually increased the price of the plain pellets at one feeder, while the price at the alternative feeder (which contained either plain or citric-acid-flavored pellets) remained low, the rate of eating (profitability) decreased at the higher-price feeder, and the rats shifted their intake toward the less-costly, more profitable pellets. We compared the relationship between the relative eating rate at each feeder and the relative meal size (or daily intake) at each feeder when the low-priced food was plain and when it was flavored with citric acid, and found no differences. This indicates that taste may influence choice via its effect on rate of intake.