- Taste responses of the Columbian black-tailed deer,
Odocoileus hemionus columbianus (Richardson), were determined
by use of the two-choice preference test method, where the choices
were tap water and tap water-chemical solutions in ascending
concentrations. The chemicals tested were: the sugars, glucose
and sucrose; the sodium salts of chloride (NaC1) and acetate (NaAc);
the acids, hydrochloric (HC1), acetic (HAc) and butyric (HBu); and
quinine sulfate (QSO₄), quinine monohydrochloride, and saccharin
(the non-sodium, crystalline form).
Animals used in the study consisted of twelve deer, half
bucks and half does, plus four Hampshire sheep as a control group
for comparison with previous work. The deer, initially about five
months old, were penned by sex into four groups of three deer each.
The separately penned groups were fed ad libitum pelleted alfalfa hay and Fischer's calf grower. Responses were determined by
expressing the consumption of test fluid as percent intake of the
total fluid consumed for a given time period.
The non-discrimination zone was derived by determining
the normal variation, with tap water in both containers, around a
theoretical mean intake of 50% from each container. To determine
if there were differences in response due to sex both graphical
analysis and a paired "t" test were used.
The chemical concentrations at the preference and rejection
thresholds for deer were 57% and 43% of total fluid intake, respectively.
For sheep the non-discrimination range was calculated to
be from 44% to 56%.
Specific results are as follows:
1. Deer demonstrated stronger preferences for sweet solutions
than sheep. The average sensitivity levels of deer and sheep for
glucose were at 0.0294 M and 0.1388 M, respectively. The average
sensitivity level of deer for sucrose was at 0.00705 M and the sheep
were too variable for determination.
2. Deer preferred saccharin over a wide range of concentrations
but to a much lesser degree than for the two sugars. Sheep
were variable in response. The average sensitivity levels of deer
and sheep for saccharin were at 0.0298 mM and 0.1024 mM, respectively. 3. Deer strongly preferred sodium acetate but not sodium
chloride. Sheep were variable in response to both salts. The
average sensitivity levels of deer and sheep for sodium chloride
were at 0.1516 M and 0.2352 M, respectively. The average
sensitivity levels of deer and sheep for sodium acetate were at
0.0085 M and 0.0353 M, respectively.
4. Deer exhibited a wide range of fairly strong preference for
acetic acid, but not for butyric and hydrochloric acid. Sheep
demonstrated distinct rejection trends for all three acids. Test
results with sodium acetate and acetic acid verified the strong
preference of deer for the acetate radical. The average sensitivity
levels of deer and sheep for acetic acid were at 0.0011 M and
0.1049 M, respectively. The average sensitivity levels of deer and
sheep for butyric acid were at 0.0100 M and 0.0014 M, respectively.
The average sensitivity levels of deer and sheep for
hydrochloric acid were at 0.0258 M and 0.0021 M, respectively.
Deer clearly rejected the volatile fatty acids (acetic and butyric
acid) at a higher pH than hydrochloric acid which has a less
5. Definite sex differences were observed in the bitter taste
response of deer. Bucks demonstrated a marked preference for
bitter solutions while the does and sheep rejected them. The average sensitivity levels of deer and sheep for quinine sulfate
were at 0.0386 mM and 0.1596 mM, respectively. The average
sensitivity levels of deer and sheep for quinine monohydrochloride
were at 0.0283 mM and 0.0204 mM, respectively.
6. Among glucose, sodium chloride, acetic acid and the
quinine compounds, the quinine compounds are the most effective
taste stimulants (i. e. , accepted at the lowest concentration).
Acetic acid is next in effectiveness, followed by sodium chloride and
7. Based on the sum of sensitivity levels of deer, sheep, goats
and calves in a sensitivity series for each of the primary taste
modalities, goats appear to be the most sensitive, followed by deer,
calves and finally by sheep.
8. Species differences in taste responses appear to be a product
of the evolutionary process.
9. Future studies of more ruminant species are requisite to a
basic understanding of taste responses and all of their applied