Ruminants learn to avoid many foods that contain toxins by associating
the flavor of the foods with aversive postingestive feedback. We hypo
thesized the emetic system is a cause of aversive feedback, and three
experiments were conducted to determine whether antiemetic drugs (diph
enhydramine, metoclopramide, dexamethasone) would attenuate food avers
ions caused by the toxicant lithium chloride (LiCl). Lambs were assign
ed to one of four treatments: antiemetics plus LiCl(A+L), antiemetics
alone (A), LiCl alone (L), or neither antiemetics nor LiCl(C). The LiC
l was administered immediately after sheep ate oats, wheat, and mile i
n Exp. 1, 2, and 3, respectively. The antiemetics were given Ih before
and at the time LiCl was administered to sheep. Lambs that received a
ntiemetics (A and A+L) consistently ate more grain than lambs that did
not receive the drugs(C and L) (Exp. 1, P <.08; Exp. 2, P <.05; Exp.
3, P <.08), and there was no interaction between antiemetics and LiCl.
Thus, the results of all three experiments were consistent with the h
ypothesis that antiemetic drugs attenuate food aversions caused by the
toxicant LiCl because sheep receiving antiemetic drugs (Group A+L) at
e more grain than sheep not receiving the drugs (Group L). In addition
, we suggest aversive postingestive feedback limited intake of grain b
ecause sheep receiving antiemetic drugs (Group A) ate somewhat more gr
ain than sheep not receiving the drugs (Group C).