U.S. Department of Agriculture: Animal and Plant Health Inspection Service
Date of this Version
October 2004
Abstract
Multiple experiments were conducted with a mammalian herbivore to determine how experience
with plant secondary metabolites (terpenes and tannins) influenced acquisition of new aversions to
diets containing these same plant metabolites. Goats (Capra aegagrus hircus) were employed as
behavioral models for this study. Twenty-four subjects were assigned to three treatment groups that
received 20 days of experience with test diets: (A) terpene diet only; (B) tannin diet only; and (C)
terpene and tannin diets offered singly on alternate days. In experiment 1, all subjects were offered
both diets in a two-choice test to determine if experience affected diet preference. Both treatments A
and B demonstrated significant preferences for the terpene diet, while treatment C subjects did not
exhibit a diet preference.
Both diets were offered to all subjects and immediately followed with a 150 mg/kg dose of lithium
chloride (LiCl) in experiment 2. A two-choice preference test was conducted to determine if lithiuminduced
toxicosis would be associated with the least familiar diet. As in experiment 1, treatments A
and B preferred terpene diet while treatment C did not demonstrate a preference. Lithium chloride
exposure was specifically paired with one of the test diets in experiment 3. A two-choice preference
test demonstrated that treatments A, B, and C acquired aversions to tannin diet when it was paired
with LiCl administration. However, terpene-paired LiCl administration did not produce an aversion
to the terpene diet in treatments A and B. Treatment C preferred tannin diet when the terpene diet was
paired with LiCl.
A novel flavor was added to the choice of diets in experiment 4. All subjects were offered citric
acid (CA), terpene, and tannin-containing diets and immediately dosed with LiCl. Subjects that
acquired aversions to the tannin diet in experiment 3 continued to avoid tannin diet in experiment 4
and preferred terpene diet while eating significant quantities of the novel CA diet. Only treatment C
subjects with previous terpene-paired LiCl exposures demonstrated aversions to the CA diet. These
results have implications for the conduct of flavor aversion studies and the application of flavor
aversion learning (FAL).
Comments
Published by Elsevier B.V.