ANTIEMETIC DRUGS ATTENUATE FOOD AVERSIONS IN SHEEP

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).