Acquired aversions as the basis for varied diets of ruminants foraging on rangelands

Summary

Provenza presents a theory of acquired aversions as the primary mechanism underlying the dietary diversity observed in grazing ruminants. The theory proposes that involuntary aversions—arising from both sensory properties (taste, odour, texture) and postingestive physiological effects—cause animals to reduce preference for recently consumed foods, thereby promoting a varied diet. This framework encompasses toxin avoidance and nutritional acquisition whilst explaining why herbivores seek variety even when nutritional needs are met and toxins are absent.

Regional applicability

The theory applies directly to United Kingdom upland and lowland grazing systems, where multi-species swards and forage diversity are managed for pastoral livestock (sheep, cattle). The mechanistic explanation of voluntary dietary selection is relevant to UK rangeland and pasture management practice, though empirical validation in UK-specific contexts would strengthen application to local grazing conditions and plant communities.

Key measures

Conceptual framework linking sensory input, postingestive effects, and preference reduction; mechanisms of aversion formation and their functional outcomes (toxin avoidance, balanced diet acquisition, rumen microflora maintenance).

Outcomes reported

The paper proposes a theoretical framework explaining how ruminants achieve dietary diversity through acquired aversions to foods based on sensory and postingestive cues. It posits that aversions—triggered by toxins, nutrient imbalances, or satiety—explain varied foraging behaviour independent of conscious nutritional decision-making.

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