“Flavor Preferences in Cats (Felis Catus and Panthera Sp.)”, 1977 ():
4 experiments examined flavor preference in cats:
domestic cats exhibited no preference (both in 24-hr and 1-hr two-choice preference tests) for any of a variety of carbohydrate or artificial sweeteners regardless of whether a water or saline diluent was employed. A preference for sucrose or lactose dissolved in dilute milk compared with dilute milk alone was observed.
…However, our findings are in disagreement with those of et al 1971 in that in our experiments the use of 30 mM NaCl as the diluent for sucrose (or for any other sweetener) did not result in an avidity for this mixture. The difference between our findings and those of et al 1971 could be due to differences in the sample of felids and/or to the different testing procedures employed…This preference may have been based on textural rather than flavor characteristics of the milk-sugar solution.
a similar lack of preference for carbohydrate sweeteners was found when using 5-min two-choice preference tests with wild cats (genus Panthera [lions, tigers, leopards, jaguars]).
In light of this lack of sweet preference among cats, Experiments 3 and 4 examined responses to solutions of hydrolyzed protein and individual amino acids and to emulsified fat mixtures.
Solutions of hydrolyzed soy, lactalbumin, and casein; L-alanine and L-proline solutions; and butterfat mixtures were all preferred to the diluent.
It is suggested that a pattern of responses characterized by an avidity for protein and fat products and no avidity for carbohydrate sweeteners may be typical of strict carnivores like cats.
…Although our results are consonant with most electrophysiological studies and support the conclusions of 1956, they are in disagreement with those of et al 1971 concerning the ability of a 30 mM saline diluent to induce a preference for sucrose. Several possible explanations for the differences between the work of and our studies can be eliminated. First, since we used a large number of domestic cats as well as wild cats, it seems unlikely that our samples were aberrant. Second, we conducted many tests with a variety of sweetening agents and found no evidence for the efficacy of the 30 mM saline diluent, thus eliminating the possibility that our data were produced by restricted testing. Third, use of 3 testing paradigms (24 hr, 1 hr, and 5 min) reduces the likelihood that our testing procedures would miss a dramatic result such as that described by Bartoshuk et al(197153ya). Finally, the possibility that the lack of preferences may be due to conditioned aversions is unlikely. Intake of large amounts of sucrose (and other sugars) has been reported to make cats sick (eg. 1956). However, the sugars in dilute milk experiments, in which there was a statistically-significant preference for the sugar-milk mixture compared with diluted milk alone, were done after all other testing. If conditioned aversions had been formed and the response was to the sweetness of the dilute milk-sucrose solutions, one would have expected an avoidance of the mixture instead of the preference we observed. Further, if conditioned taste aversions were formed, one would expect the solutions of sugar in saline to be avoided; instead, cats ingested them indifferently compared with diluent.
A remaining methodological difference between our testing procedures and those of et al 1971 was that for each experiment with each sweetener tested, we used only one group of animals at each concentration. Bartoshuk et al however, repeatedly tested the same 9 cats with increasing concentrations, first, of sucrose versus water and, second, with sucrose-saline solutions versus saline. For each concentration of sugar tested by these investigators, cats were allowed access for 6 hr each day for 4 consecutive days. Rest days separated testing at each concentration. Although is it not readily apparent how this discrepancy could account for our different results, perhaps some form of sensitization resulted from the repeated testing paradigm with step-wise increasing concentrations. A related hypothesis, that neophobic responses to carbohydrates by cats in our experiments could explain the differences, is unlikely, since this would predict that the sweeteners would be rejected, compared with the diluent, rather than ingested indifferently, as we found to be the case. Although we cannot reject the possibility that methodological differences could explain our differential findings, we conclude that our more extensive tests strongly indicate that the saline diluent is not generally effective at inducing cats to exhibit preferences for carbohydrates.