depends on if your horse is a stalled horse or a pasture horse. pasture horses normally founder easliy. and stalled horses don't founder so easliy so it depends.
Answer:Actually, horses do not founder becasue of pasture, as you can see in the related link. A horse should be kept in "natural boarding" 24/7, and they will constantly eat to keep their small bellies filled for about 18-20 hours a day, and this will total to about 2% of their body weight. Given free choice grass or grass hay, a horse will eat the correct amount; some how they just know what they need.