GrazeVision: A versatile grazing decision support model

Grazing management, i.e. matching the grass supply with feed demands, is complex. It involves many interventions such as varying the length of grazing rotation, nitrogen fertilization, supplementation, access time, stocking rate, paddock size, removal of surplus grass and topping. It is difficult to foresee the effects on animal and grassland production when two or more interventions are executed simultaneously. The GrazeVision decision support model is developed for farmers to simulate the effects of one or more management interventions at the same time. The inputs for GrazeVision are: nitrogen application rate, soil, season, target residual herbage mass, herd demography, paddock size, access time and supplementary feeding. The outputs are: predicted initial herbage mass, herbage intake, substitution rate of supplemental feeding, paddock residence time, herbage available for cutting, rejected herbage mass (tall patches), herbage loss due to fouling with dung, trampling and poaching, herbage utilization, total milk production and changes in milk production during paddock residence time. Farm profitability is calculated after allocation of input prices and product returns. The GrazeVision grazing decision model is incorporated in the DairyWise whole-farm decision model and available as a stand-alone internet application www.koeenwij.nl.