Foraging behaviour and diet selection in domestic herbivores

Foraging behaviour and diet selection determine both the nutrient intake by the ani- mals and their impact on the vegetation. They are therefore of importance for animal and vegetation management. Animals exploit the heterogeneity of resources through selective grazing, choosing a diet of better quality than the average vegetation on offer. Recent increased effort has been made to develop models of the grazing process supported by theory, which should facilitate generalisation and application to a broad range of situations. Foraging involves the interactions between the charac- teristics of the animal and the characteristics of food in the environment. We review some of the animals' foraging decisions within the vegetation, morpho-physiological, digestive and behavioural constraints they face. The determinants of foraging behaviour and diet selection remain, however, some- what obscure and a matter of debate. The complexity of the animal/vegetation interactions have prompted the development of simple experimental approaches, and further research is needed to extrapolate these to larger spatio-temporal scales. @ Elsevier / Inra foraging behaviour / dietary choices / grazing Rsum — Comportement d'ingestion et choix alimentaires au pturage chez les herbivores domestiques. Le comportement d'ingestion et les choix alimentaires au pturage conditionnent l'ingestion de nutriments par les animaux et leur impact sur la vgtation. Une meilleure comprhension de leurs dterminants est donc importante pour grer la dynamique des systmes pturs. Les animaux exploitent l'htrognit des ressources en pturant de manire slective et en choisissant un rgime de meilleure qualit que ce qui leur est offert. Un effort rcent a t fait pour dvelopper une approche hirarchise du processus de pturage, taye par des bases thoriques, afin de dgager des lois gnrales applicables des situations varies. Le comportement d'ingestion et les choix alimen- taires rsultent de l'interaction entre les caractristiques des animaux et celles de la vgtation offerte. Cette revue prsente certaines dcisions des animaux face aux contraintes qu'ils rencontrent, qui sont lies la vgtation, leurs caractristiques morpho-physiologiques propres, ou au temps dont