Comparison of Gustatory Responses to Amino Acids in Pigs and in Humans

Combining a specific conditioning with a two-choice preference method, the gustatory response of pigs towards 29 -amino acids was studied. It was found that among the amino acids known to have a predominant sweet taste in humans, 12 were preferred over water in pigs, while four were refused (D-His, D-Leu, D-Ile and D-Val). All the amino acids which were known to be sweet in humans under both their L- and D-forms were also preferred over water in pigs. The molar order of effectiveness of amino acids in pigs (D-Trp>D-Phe>D-AsnL-Hyp>D-Ala>GlyL-Ser>D-SerDThrL-Thr) was similar to that of their sweetness potencies in humans. However, in pigs, their efficiency relative to sucrose was ~3 to 4 times lower for D-Phe, L-Hyp, D-Asn, D-Ala or Gly, and ~15 times for D-Trp.