หน้า8 humans perceive as bitter-tasting. Plant extracts and pharmaceutical compounds resulted in aversion behaviors in pigs some of which were found to be dose dependent. Pigs have a strong preference for sucrose and a more moderate preference for glucose, lactose, and salt. Therefore, flavoring agents, e.g. sugar, have been used for weanling pigs to create interest in them for solid food (Forbes, 1995). The first work reported on sugar preferences was published in the mid 50s (Salmon-Legagneur and Fevrier, 1956). Kennedy and Baldwin (1972) have examined the taste preferences of pigs for nutritive and nonnutritive sweet solutions over a wide range of concentrations and found that young pigs prefered sucrose solution at concentration above 10.3 g/L. Pigs also preferred water containing greater than 1.8 g/L for glucose solutions, although the consumption volume was lower than sucrose. This indicated that sucrose was the more strongly preferred sugar. Saccharin was also preferred at concentrations from 1 to 2 g/L compared to nonsupplemented water, but higher concentrations (above 18 g/L) decreased the preference substantially. The rejection of high concentrations of saccharin may be due to the bitter taste associated with high concentrations of the chemical. Not all non-nutritive sweeteners stimulate attraction in pigs. Nofre et al. (2002) investigated the responses of pigs to 60 artificial sweetener compounds and found that 35 compounds were attractive to pigs, but less so in pigs than in humans. Lugduname and carrelame, the two most potent sweeteners in humans, are also the most effective compounds in pigs.