FOOD AVERSION CONDITIONED IN ANESTHETIZED SHEEP

We discovered that a food aversion could be conditioned in anesthetize d sheep. Sheep were allowed to eat a familiar food (alfalfa-grain pell ets) for 30 min, and 90 min later they were given either an intrarumin al (IR) injection of water (C), an IR injection of LiCl (L), anesthesi a followed by an IR injection of water (A), or anesthesia followed by an IR injection of LiCl (A+L). Induction of anesthesia was by an intra veneous injection of pentobarbitone sodium, and maintenance of deep an esthesia was by halothane. Sheep were maintained in deep anesthesia fo r 2 h to ensure that the effects of LiCl on the acquisition of a food aversion, which occur within about 1 h, were completed before they awa kened. When tested 5 days later, sheep that received LiCl (treatments L and A+L) consumed less alfalfa-grain pellets than sheep that did not receive LiCl (treatments C and A) (241 g vs. 306 g; p = 0.057). Intak e of sheep that were anesthetized (treatments A and A+L) did not diffe r from that of sheep that were not anesthetized (treatments C and L) ( 295 g vs. 252 g; p = 0.183). Nor was there an interaction between LiCl and anesthesia (p = 0.423). Thus, we conclude that changes in prefere nces for foods caused by postingestive feedback occur automatically ev ery time food is ingested (i.e., they are noncognitive), and the kind and amount of feedback is a function of the match between the food's c hemical characteristics and its ability to meet the animal's current d emands for nutrients.