I would be real careful of carbohydrate overload that could result in founder if we have a wet spring. Rye is rich in sugar and wet years will really push the growth on that stuff resulting in a very carbohyrate rich buffet. While great for cows, it can and often does result in foundering horses. They say that a good way around this during the height of its growing season is to wait to graze your horse on the stuff until the dew burns off of it. Something about the grass pulling more nutrients up when its wet.
I'm afraid I've been there and done that. Lost the best horse I ever had or ever will have due to foundering while grazing a rye pasture. This was about 4 years ago when we had a really wet spring. The vet said that he had seen quite a few cases of founder that year due to the wet spring and rye pastures. Hours and hours of research done on foundering, its causes and cures basically resulted in the above summary. I'm sure I'm paranoid about it now, but an ounce of prevention is worth a pound of cure, and that is one thing I never ever want to see again.
