Models for predicting effects of management factors on per-cow and per-hectare pasture intake by grazing dairy cows

摘要

Robust modelling of pasture herbage intake by grazing dairy cows under a wide range of grazing and supplementary feeding strategies allows the better combination of high rates of pasture utilisation and nutrition management in dairy systems. The Grazeln model has been developed from 10 years at INRA (France) from extensive literature review and large experimental databases, and then validated at European level. It allows prediction of the effects of animal characteristics, sward nutritive value, grazing management (grazing system, pasture allowance, pasture mass, daily access time) and supplementation (concentrates and/or forages), along with their interactions, on daily pasture dry matter intake by grazing dairy cows. Grazing management and sward structural characteristics are, however, often unknown on farm. For that reason, a simplified version of the model describing sward state and management through only pre-grazing and post-grazing sward heights has also been developed, allowing easier use of the model for advising or teaching. After a brief description of the two versions of the model, the relative effects of the main factors affecting pasture intake are compared on a per-cow and on a per-hectare basis.