Behavioral Study on Taste Responses of Geese to Sweet, Salty, Sour, Bitter, and Umami Solutions

Abstract

The objective of the present study was to obtain basic information on the potential of geese as biological control agents for weeds in agricultural fields. Taste responses of geese to sweet (sucrose), salty (sodium chloride), sour (citric acid monohydrate), bitter (quinine hydrochloride), and umami (monosodium glutamate) taste solutions were studied during the two-choice preference tests. The aforesaid substances were dissolved in tap water to create 11 stepwise test solutions by doubling the concentrations. Percentage of intake of the test solutions to total fluid at each concentration was defined as the preference index. A preference index above 60.3% was defined as the preference zone, below 39.7% was the rejection zone, and between 39.7% and 60.3% was the nondiscrimination zone using the χ²-test (P < 0.05). Geese showed no　preference and rejection to the sucrose solution between 0 and 20% concentration. In contrast, they rejected concentrations above 2.5, 0.32, 0.04, and 5% of sodium chloride, citric acid monohydrate, quinine hydrochloride, and monosodium glutamate solutions, respectively. In conclusion, geese showed no preference to any taste of sweet, salty, sour, bitter, and umami; however, they did aversively respond to the bitter solution at lower concentration levels compared to the sweet, salty, sour, and umami solutions. Therefore, geese are more sensitive to bitter than to sweet, salty, sour, and umami, indicating that they are selective about their grazing diet which is based on the taste.