Pelleted feeds can, however, cause digestive problems when fed alone and a diet consisting solely of pellets results in less time spent eating and can lead to boredom and increased wood or tail chewing. In general, forages are lower in digestible energy and higher in fiber than grains. Although crude protein content varies among forages, large amounts of minerals and vitamins are supplied by them. Due to higher energy requirements, horses at hard work or brood mares with foal cannot eat enough of an all-roughage diet to furnish all the nutritional requirements. Oats are the primary grain in most rations because they are lower in energy and higher in fiber than most grains and their bulky nature results in less digestive upset.
Corn is high in energy but low in protein quality and quantity.
Corn is considered a heavy grain because it is denser and higher in energy per unit weight compared to oats. Oats, corn, milo, barley and wheat are energy feeds. Protein sources include soybean meal, linseed meal and sometimes, alfalfa pellets. When compared to soybean meal, linseed meal is a lower-quality protein as it is low in lysine. Most grains, however, have adequate protein to meet the needs of mature horses, either idle or working.