How goats learn to distinguish between novel foods that differ in postingestive consequences

Area of Science:

• Animal Behavior
• Nutritional Ecology
• Plant-Herbivore Interactions

Background:

• Understanding how herbivores select novel foods based on postingestive feedback is crucial for nutritional ecology.
• Blackbrush (Coleogyne ramosissima) offers contrasting nutritional profiles between current season's growth (CSG) and older growth (OG).
• CSG is richer in nitrogen and more digestible but contains higher levels of condensed tannins, potentially leading to learned aversions.

Purpose of the Study:

• To investigate the mechanisms controlling food selection in goats when presented with novel foods differing in postingestive consequences.
• To determine the role of learned aversions, ingested amounts, and flavor salience in food choice.

Main Methods:

• Goats were offered CSG and OG blackbrush twigs, with varying amounts ingested and controlled toxin (lithium chloride) administration.
• Food selection, intake, and learned aversions were monitored in goats naive to blackbrush.
• The influence of flavor salience (taste and odor) on aversion learning was assessed.

Main Results:

• Goats initially did not exclusively choose CSG or OG but developed a preference for OG after experiencing negative postingestive feedback from CSG.
• Aversion learning was influenced by the amount of food ingested within a meal; larger amounts led to reduced subsequent intake of that food.
• Flavor salience, particularly a common flavor concentrated in CSG, played a role in the acquired aversion.

Conclusions:

• Goats learn to distinguish between novel foods based on postingestive consequences, developing aversions to foods causing negative feedback.
• The quantity of food consumed within a single meal and the salience of its flavor are key factors influencing learned food aversions.
• These findings highlight the complex interplay of nutritional content, learned experience, and sensory cues in herbivore foraging decisions.