Grass or hay (dried grass) should almost always make up the base of a horses diet. Fresh green grass can cause health problems in certain horses though. Horses can also have certain types of grains, fruits and vegetables. There are some foods that are toxic or poisonous to them and should be avoid at all times. Sugar is also not good for horses.
Mammal + Grass = Horse
Besides a seahorse, a horse that has foundered on grass must be kept away from grass. Green, lush grass could kill an already foundered horse. (ponies are at greater risk)
Removing the horse from the offending grass will rectify grass allergies. Ask your veterinarian, but hay is a substitute that usually won't bother a horse with this problem.
I've personally never heard the term 'to grass a horse'. However the term to 'putting a horse out to grass' or 'the horse is on grass' are widely used in the UK. I would assume therefore that it would be the same thing as those terms. A horse at grass means it is eating pasture grass and may or may not be supplemented with hay or hard feeds.
A sea horse.
Mammal + Grass = Horse
My Horse is an interactive online game about raising horses. You can plant treat grass for the horse to eat on the game.
Rye grass
No good with a dead horse.
No but there are many plants in the grass that can.
Hay as well as horse feed and grass.
a white horse eat hay and grass