Conditioning taste aversions to locoweed (Oxytropis sericea) in horses.

The research article discusses a study into methods of preventing horses from consuming locoweed, a plant poisonous to them, by conditioning aversion using substances like lithium chloride or apomorphine.

Research Objectives

• This research was undertaken with two primary objectives in mind:
  • To ascertain whether the administration of lithium chloride or apomorphine could trigger distaste towards delicious foods in horses, and at what doses this effect could be achieved.
  • To investigate if horses could be discouraged from consuming fresh locoweed in a controlled setting and while grazing.

Key Findings

• Apomorphine was discarded as a viable aversive agent due to the unacceptable behavioral effects it produced in horses, even at the minimum dose required to initiate an aversion.
• Lithium chloride, however, was found to be effective in creating strong and lasting aversions to palatable feeds in horses, with only minor signs of distress noted. Administered via a stomach tube, a dosage of 190 mg/kg body weight was used.’
• In pen tests conducted, it was found that most horses (5 out of 6) completely refrained from consuming locoweed. The treated horses consumed significantly less locoweed compared to the controls.
• In a grazing situation, one treated horse continued to eat locoweed when offered in the pen but refrained from doing so while grazing. The overall locoweed consumption by the control horses was considerably higher than that of the treated horses.
• One treated horse, who initially consumed a significant percentage of locoweed, required a second dose of lithium chloride before it stopped eating the weed altogether.

Conclusion

• The study results conclusively show that lithium chloride can be used effectively as an aversive agent, conditioning horses against locoweed consumption. This could offer a valuable tool for managing the risk of poisoning in horses grazing on locoweed-infested land.