“The biggest benefit of alfalfa for horses is that it tends to be more nutrient-dense than most grasses when harvested at the same stage of maturity,” says Martinson. It typically contains more digestible energy, more crude protein and calcium, and fewer nonstructural carbohydrates (sugars and starches).
Because it’s so nutrient-dense, it is a good feed for underweight horses. “It can also be beneficial to horses with muscle problems that are prone to ¬tying-up (due to their increased protein needs) or horses with equine metabolic syndrome (EMS) due to the lower amount of nonstructural carbohydrates,” says Martinson. She says alfalfa is ideal for horses on high planes of nutrition, such as lactating broodmares, growing horses, thin horses, racehorses, performance horses, or young foals that aren’t getting enough milk. With growing horses, however, use caution in the amount fed, simply so they don’t grow too quickly or get too big too fast and become at risk for DOD (developmental orthopedic disease),” Martinson says.
We know that for horses sensitive to sugar or carbohydrates (e.g., horses with insulin resistance, pituitary pars intermedia dysfunction, etc.), building a diet on a good foundation of forage is especially important the oats, corn, and barley that make up many feeds are 55-75% carbohydrate. Some grass hays are also too high in sugar for these horses, and this is where a legume diet or mixed legume/grass diet can help lower total sugar intake. Choosing the right hay for proper balance can be challenging, however. For instance, a horse that’s overweight and insulin resistant needs a lower-sugar hay (the alfalfa), says Martinson, but not the additional calories, “So we often end up doing a mix where those horses receive some legume and search for a low-sugar grass hay to mix with it.”
“Many horse owners buy bales of alfalfa and bales of grass hay and feed several flakes of grass hay and one flake of alfalfa” as needed, says Krista Lea, MS, forage extension specialist and research analyst at UK. This can offer some cost savings if you also have horses that do fine on the less-nutrient-dense hay. I have three horses with three different nutrient requirements, so if I have different kinds of hay I can mix them appropriately for each horse—to get the right balance for what they need,” she says. You can add alfalfa pellets or cubes to a grass hay diet for the same effect.
Alfalfa is also suitable for horses prone to gastric ulcers because the extra calcium acts as a buffer against stomach acid. You might offer performance horses alfalfa an hour or two before work or competition, during which acid can splash up into the non-glandular part of the stomach (where the cells of the lining do not produce protective mucus). The simple act of chewing creates more saliva, which also helps buffer stomach acid, says Lea.
Owners might also offer the legume to horses needing to develop more muscle, particularly along the topline. Stephen Duren, Ph.D., equine nutritionist and founder of Performance Horse Nutrition, in Weiser, Idaho, says this is because alfalfa provides amino acids needed for muscle regeneration. “We see this practice more in the East where a lot of marginal grass hay is fed.