The olfactory detection of sodium and lithium salts by sodium deficient cattle

With development of Na+ depletion in cattle enhancement in the specific ability to smell very low concentrations of salt occurs. At the same time a behaviour pattern develops, in which increased locomotory activity is seen, directed towards searching for sodium salts. Following the initial successful location of a sodium source the pattern once learned, is consolidated by repetition and by consummation of the salt reward. Our data shows that olfactory and gustatory receptors are able to detect minute amounts of sodium salts as biochemical disruption develops with Na+ depletion but the central input from smell and taste receptors remain distinct. Salt appetite does not appear to be pleasurable (hedonic) in cattle, for salt appetite which is a feature of Na+ depletion does not persist when the ionic deficit is restored. The innate behaviour which develops with increased salt appetite in cattle may account for the evolutionary success and worldwide distribution of ruminants.