Preference for diverse pastures by sheep in response to intraruminal administrations of tannins, saponins and alkaloids

Summary

This experimental grazing trial demonstrated that sheep adapt their foraging behaviour to mitigate the negative effects of plant secondary compounds by selectively increasing intake of complementary PSC-containing forages whilst avoiding over-ingestion of any single compound. When challenged with intraruminal administration of tannins, saponins, or alkaloids, lambs showed increased grazing preference for forages containing different PSCs, suggesting animals use dietary diversity as a self-medication strategy.

Regional applicability

The findings are relevant to temperate pasture systems including the United Kingdom, where birdsfoot trefoil, alfalfa, tall fescue and orchard grass are commonly used forage species. The results support integrated grazing management practices that provide diverse forage choices to enhance animal health and welfare, applicable to UK grassland farming.

Key measures

Foraging behaviour recorded as scan counts at 1-minute intervals on four forage species; preference responses to intraruminal administration of condensed tannins, saponins, and ergotamine

Outcomes reported

The study measured how lambs modified their foraging behaviour and grazing preference across four forage species when administered single plant secondary compounds (tannins, saponins, alkaloids). It documented changes in scan frequency on different forages in response to intraruminal dosing.

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