Taste aversion learning in horses.

This research article focuses on a study conducted to understand if ponies could learn to avoid a food that previously caused them to fall ill. The study found that ponies developed a taste aversion if illness occurred immediately after eating, but did not avoid a feed if illness happened 30 minutes later. There were also variations in the type of feed the ponies learned to avoid.

Study Design

• The researchers tested the ability of ponies to avoid food associated with illness in three scenarios:
  • illness occurring immediately after eating a feed
  • illness occurring 30 minutes after consuming the feed
  • illness as a result of consuming one out of three types of feed offered at the same time
• The feed types involved were corn, alfalfa pellets, sweet feed, and a complete pelleted feed.
• They injected ponies with apomorphine, a drug that induces vomiting, to simulate an illness associated with the consumed food.

Study Findings

• Ponies displayed learning capabilities as they learned to avoid any feed associated with immediate illness induced by apomorphine, except for the complete feed.
• The study revealed that the timing of illness plays a role in this learning as ponies did not learn to avoid a feed if the induced illness was delayed by 30 minutes after eating.
• When presented with their regular meals (“safe foods”) alongside alfalfa pellets and corn, ponies learned to avoid alfalfa pellets but not corn. This indicates that ponies could distinguish the feeds causing illness from their usual diet.

Study Implications

• The study recognises that ponies have the ability to learn food aversions based on a previous sickness experience.
• However, this learning ability is bound by constraints like the timing of sickness and the type of feed.
• The study concluded that ponies had a harder time developing an aversion to highly palatable feeds. Furthermore, they did not develop an aversion to a feed if the illness occurred long after consumption, suggesting a limited window in which the association between the food and illness can be learned.