Abstract This review addresses models associated with the utilization of herbage by grazing animals. Animal products from grazed herbage are economically and socially important throughout the world. The review focuses on the role of modelling at farm level and provides a broad picture of herbage utilization while focusing on grazing, with the objective of assessing how modelling contributes to increasing the efficiency of livestock production in systems where herbage utilization is the principal source of feed. Systems of production can vary widely according to climate, soil and social conditions, yet the review does not attempt to deal with all possible systems of herbage utilization, rather the focus is on livestock production in temperate climates. In this regard, the scope might be considered somewhat restricted, but it still presents a general assessment that is relevant to a wide range of circumstances. By focusing on the grazing component, the review addresses neither the mechanical harvesting of herbage as silage or hay, nor the environmental aspects of livestock systems that have become very important in recent years. These subjects constitute major areas of investigation in themselves and should be reviewed separately.
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