A low fructan concentration in grass prevents the risk of laminitis. Fructan is a carbohydrate (a type of sugar) that is produced by grass plants under the influence of sunlight. Especially in the case of cold nights and intense sunlight, grass plants produce large amounts of fructan.
Horse grass is not yet a matter of course in the Netherlands. Most horses graze in cow pastures and are fed hay or silage from those pastures. Horses find that grass very palatable, but it is actually far too high in energy (fructan) and contains too little effective fibre.