It`s not "no alfalfa for performance horses", it`s "no alfalfa EXCLUSIVELY for performance horses". The primary reason is because it`s too high in protein. Even poor grade alfalfa is usually 15-16%, and good, leafy, rich alfalfa is often way over 20%. Protein contains large amounts of nitrogen, which in the body is degraded to ammonia. Ammonia is toxic, so the body tries to get rid of it, either via sweat, or through the urine. Alot of nitrogen coming out through the sweat glands is in part what produces that thick, patchy, lathery sweat which is much less efficient in cooling the horse than the thin, clear, watery sweat.
Two, to dilute all that ammonia, the horse has to urinate more. In an endurance situation, he`s losing more body fluids than he would be without the excess ammonia problem, and is more likely to become dehydrated during an endurance ride. If the horse is kept in a box stall, as many are, the amount of cleaning and bedding is going to be increased. Ammonia fumes are going to be greater (in other words, the stall stinks) which is hardly a good thing for the upper respiratory tract.
Three, there is some evidence (Glade, Equine Veterinary Journal 15(1) 31-36, 1983) that excess protein slows energy production. In 171 Thoroughbreds running in 563 races, the time required to finish 1673 meters increased by 3 seconds for every 1000 grams of crude protein that were fed in excess of NRC recommendations. Endurance horses don`t tend to sprint much, but why do anything that might impede energy production?
Four, while alfalfa is excessive in protein, it is deficient in energy compared to any of the grains. The vast majority of performance horses are deficient in energy, which is why so many people are always trying to get more weight onto their horses with corn oil, rice bran, whatever. This is becoming even more important now that some data is coming out that horses with a little fat on them do better than hat-racks do. While excess protein can be utilized for energy production, it is much more expensive to try to put fat on a horse by feeding excess protein than is is to provide more energy in the form of an energy feed.
Five, west coast alfalfa especially is very high in magnesium---the alfalfa plant seems to have the ability to concentrate magnesium, they don`t know why. Magnesium, ammonium and phosphorus are the three minerals which primarily make up enteroliths (gut stones). If you`re feeding alot of alfalfa, you`re feeding alot of magnesium. AND you`re feeding alot of ammonium from---you guessed it---all that nitrogen in alfalfa`s protein content. Now all you need is a nice load of phosphorus, from say, rice or wheat bran or lots of grain. Guess what lots of performance horses are fed? Is it any surprise that enteroliths are such a problem in causing colic in horses? Here in So Cal, the majority of horses are fed straight, California-grown alfalfa. And the incidence of enteroliths is higher here than in anywhere else in the country. Why would you feed a hay that is supplying two of the three ingredients needed for enterolith formation when you can get all the advantages and not nearly as much disadvantage by cutting the alfalfa ration in half? Doesn`t this start to come under the category of "no brainer"?
Six, alfalfa is very high in calcium. There is some argument that having a large supply of calcium in the diet gets the calcium-mobilizing hormones in the body "lazy". Calcium is required for muscular contraction and a fairly large amount of it is required during an endurance ride. Assuming the horse isn`t munching alfalfa every step of the way, his body MAY not be able to mobilize sufficient calcium for the work load and the chances of myopathies such as thumps MAY be increased.
There`s also something in the back of my mind about excess calcium impeding absorption of something else in the gut, but can`t remember what it is right now. Someone else will probably remember.
Seven, there is increasing evidence that some horses just don`t tolerate it well. Horses that are grumpy, grouchy, high, just all-around nasty customers VERY often settle down when taken off an all-alfalfa diet. There`s also increasing evidence that scratches may be related to high protein intake levels.
Finally, high protein diets seem to be implicated in increasing the incidences of osteochondrosis (OCD) in fast-growing foals. But that`s going into nutrition for growing horses, not performance horses, so I`ll leave that one more or less alone.
This is not to say alfalfa is bad. It`s a great feed for what it is. But you shouldn`t feed a rich, high protein hay to an equine athlete any more than you would stuff a 16 oz. top sirloin into a marathon runner every day. It`s just too much of a good thing. There ARE some instances when I might/would feed straight alfalfa for a specific circumstance, but a high-performance performance horse isn`t one of them. At Cal Poly, we teach (for all the above reasons) to keep alfalfa to less than half of the hay ration. At that level, you get all the advantages and hardly any of the disadvantages.
Hope this helps.
Susan Evans Garlinghouse
Just my 2 cents worth on the article by Susan Evans Garlinghouse. I AGREE. Although I`m only a beginning long distance rider, I have long believed alfalfa not to be the best nutritional substance for horses. And some feed companies are really pushing alfalfa based products.
My alfalfa concern is this: FOUNDER. If you`ve never experienced a case of founder in your horses, then the word probably doesn`t make you shudder as much as it does the rest of us. For the same reasons that it is not a good feed for athletes, it is also not a good feed for the backyard horse. It is simply has too much protein. It is great feed for dairy cows, but can be problematic in equines.
I live in the midwest and have had two horses founder on alfalfa pellets and on alfalfa hay. One of the horses I still have and the moral is no alfalfa at all for this boy. It has taken more money than I care to add up in farrier and vet bills to bring this horse around and he still is not completely sound. To be safe, he and my competition horse both get brome or prairie grass hay. They get a smidgen of oats each day with their vitamin and mineral supplement. The foundered boy also gets a biotin supplement.
Maybe your horse would do just fine on alfalfa, but when there are other perfectly good feeds and hays out there, why risk it??