The Thoughtful Horseman: The Lowdown on Alfalfa

Horses love alfalfa, and it appeals to us as horse owners because of its rich aroma, and deep green, leafy appearance...it just looks like it should be good for a horse to eat. But is it really the healthiest forage for horses?

The short answer: no.

Alfalfa is a popular feed choice because of its wide availability. But it is NOT grown for horses; it is grown for cattle, be they dairy or beef. There are a LOT of cattle in this country, and they do very well on premium alfalfa. But the digestive system of your typical bovine is much more complex than a horse's: they are designed to digest the very rich legume hays. Horses, with their simple, primitive stomachs, evolved to thrive on poor quality bunch grasses. Alfalfa is, quite literally, too much of a good thing. And just as a lack of essentials in the diet can cause problems, so can an overabundance.

While alfalfa is typically lower in NSC than many grass hays, it contains more simple glucose than other forages. Other hays typically contain larger concentrations of sucrose, and fructose. While prolonged fructose levels can exacerbate insulin resistance, glucose is the only sugar that causes an insulin response. This makes it a poor choice for horses with insulin resistance, Cushing's disease, or laminitis.

Alfalfa's protein content is another primary concern. The horse operates most effectively with a dietary protein intake of between 7 and 10%. Alfalfa -- even the relatively poor quality, stemmy kind -- contains an average of 15% protein. Premium dairy quality alfalfa can be well over 20%. While most horsemen will endorse protein for putting weight on a horse, adding more protein than the horse can efficiently metabolize can actually put the horse in a sort of negative energy balance. Susan Evans Garlinghouse, DVM, explains the conundrum:

"When the body utilizes excess protein for energy, it snips off the nitrogen end of the protein strand and breaks up the remaining amino acids for participation in several energy-producing metabolic pathways. In terrestrial animals, excess nitrogen goes through several chemical reactions to form urea, a waste product which is primarily removed from the bloodstream by the
kidneys and excreted by the body in the urine. A certain amount will also be excreted in the sweat, and is in part why horses on a high-protein diet often have thick, patchy, lathery sweat which is less effective in cooling than is a thin, clear, watery sweat.

In order to excrete large amounts of excess urea, the horse must drink more water and produce more urine, which in turn has a higher ammonia content. In a stall-bound horse, more bedding and labor [will] be required to control the increased urine out put. In addition, the increased ammonia fumes can irritate the upper respiratory tissues, as well as simply creating an unpleasant environment for both horse and owner. Even in horses not kept in a stall, the urine output may create a greater degree of dehydration during endurance events. These disadvantages alone more than outweigh the minimal energy benefits obtained from feeding high levels of alfalfa."

Read Garlinghouse-Evans’ article in its entirety here: http://www.shady-acres.com/susan/alfalfa.shtml

Protein is not the only overload alfalfa supplies. Another consideration is the calcium content of alfalfa. Alfalfa can deliver more than twice the necessary calcium. The ratio of calcium in the diet must be balanced with adequate -- but not excessive-- phosphorous. Excess calcium can also have a detrimental effect on the ability to metabolize other necessary nutrients. Then there's magnesium, another mineral found in overabundance in alfalfa. And guess what? Calcium, magnesium and phosphorous are three of the main components found in enteroliths (intestinal stones).

Finally, a more tangible result of feeding alfalfa, recently documented by scientific research, is increased excitability.