Lupins are predominantly a source of protein (28-34% crude protein) but also contain some fat (around 5%) and digestible fibre. Because of their low starch and high fibre content, lupins are digested efficiently in the hindgut of the horse through fermentation. Similar high-fibre feeds used in other areas of the world include beet pulp and soy hulls, although these do not have the high protein or fat content of lupins and are not as energy-dense. These characteristics make lupins particularly suitable for horses that have a low tolerance for starch-rich grains, such as oats or corn, which are digested predominantly in the small intestine. Horses with a predisposition to tying-up or laminitis, or those horses that get excitable on typical cereal grains, may benefit from the addition of lupins to the diet. Because lupins contain very little starch, they are often considered as an ideal “cool” feed, but their high protein content and the presence of alkaloids means that their inclusion should be limited to 2 kg (4.4 lb) for a 500-kg (1,100-lb) horse. Lupins are the current fad in feeding Standardbreds, and there are horses getting far more than 2 kg (4.4 lb) per day.
