ABILITY OF APOMORPHINE AND LITHIUM-CHLORIDE TO CREATE FOOD AVERSIONS IN CATTLE

Lithium chloride is the most common emetic used to create food aversio ns in laboratory animals and livestock. However, it is slowly excreted or metabolized, and requires several days for animals to recover. Bec ause of its caustic nature and the large quantities required by cattle and sheep, lithium is best administered directly into the rumen and d iluted by rumen fluid. The objective of this study was to evaluate apo morphine as an alternative emetic to create food aversions in cattle. A pilot study showed doses of apomorphine at 0.2 mg/kg BW caused some discomfort in cattle. Doses of 0.4 mg/kg BW and above resulted in seve re intoxication and excessive discomfort. We then compared intramuscul ar injection of apomorphine at 0.1 and 0.2 mg/kg BW, to the standard d ose of lithium chloride (200 mg/kg BW by gavage), and to a central tre atment (200 mi water by gavage). Four heifers (428 kg) were randomly p laced in each group. The heifers consumed flavored alfalfa pellets for 5 min, then were restrained in a chute and administered the respectiv e treatment. The strength and longevity of the aversion was tested by offering the flavored pellets in single-choice extinction trials for s ix days. The Lithium group did not consume any flavored pellets, thus maintaining a total aversion. Both apomorphine groups reduced consumpt ion to 40% of baseline intake, but the aversion extinguished by the en d of the trial. There was no difference between the two apomorphine do ses. Under these conditions, lithium chloride is superior to apomorphi ne in creating and maintaining taste aversions in cattle. (C) 1998 Els evier Science B.V.