A good transition from stable to pasture
It is important that your horse has a gradual transition from stable to pasture to allow the digestive system to get used to it. The processing of sugars can be particularly problematic for some horses. As the sugar content in grass can change from day to day, it is important to bear this in mind.
Grass produces fructan through photosynthesis. If grass growth is not inhibited by low temperatures, drought or a lack of nutrients, fructane is consumed and horses can safely graze in the field.
Here you can find the current fructan index for Belgium and France.
https://www.hoefnatuurlijk.nl/nl/fructaanindex.html