Robustesse, flexibilité, plasticité : Des processus adaptatifs révélés dans les systèmes d'élevage extensifs de ruminants

Abstract

Extensive livestock systems are characterised by limited input. In such systems animal food requirements are mainly based on grazing. Vegetation varies in terms of space and time, and is heterogeneous and sensitive to climatic changes. The low control by the breeders on the immediate environment implies that the management of extensive systems in such a context mainly depends on the adaptive ability of the animals. They have to be able to fulfill their food requirements by developing specific behaviours such as land exploration and selective intake. They also have to cope with low feed intake periods of various intensities and duration. In this paper we demonstrate that herbivores adjust their behaviour and physiological responses to cope with their environment and face constraints. Such adjustments highlight the differences between breeds in their ability to survive, produce and maintain their reproduction in a harsh unstable environment.