When researchers at the University of California, Davis, compared the effects of three different diets on rescue horses in a 2012 study, they concluded that alfalfa hay is the ideal first food for restoring starved horses to health.
Unlike calorie-rich concentrates, alfalfa hay does not cause the insulin spike and associated electrolyte depletion that can lead to the potentially fatal complication known as refeeding syndrome. Alfalfa is a good source of high-quality protein as well as the essential amino acid lysine and the electrolytes phosphorus and magnesium.
To learn more about what rescue horses need go to Rescue Horse Rehab.
The same researchers advise feeding a starved horse small, frequent amounts of high-quality alfalfa hay when beginning refeeding. Ideally, for the first three days of the rehab program, they say, a horse will eat one pound of alfalfa hay every four hours, for a total of six pounds per day divided between six feedings. On days four through 10, the researchers recommend slowly increasing the amount of alfalfa and decreasing the frequency of feeding so that eventually the horse eats four pounds of hay every eight hours, for a total of 12 pounds a day in three feedings.
After the tenth day of nutritional rehabilitation, the horse can be fed as much alfalfa as he will consume, the researchers say. In fact, continual access to forage is crucial, because the presence of fiber in the cecum allows for fermentation and the reestablishment of healthy hindgut flora.
Finally after the initial alfalfa-only refeeding period, nutritional supplements designed to help a horse safely gain weight can come in handy to ease re-introduction to grain. Most equine weight-gain supplements, which come in a variety of forms ranging from pellets to powders, are fat-based and may include vegetable and various seed oils and often times rice bran. Consult your veterinarian when choosing a product and look for one from a reputable manufacturer with equine nutritionists on staff and a phone number you can call if you have questions.
One additional note: if you are refeeding a horse in a region where alfalfa hay isn’t available, consider using timothy hay, though it offers less nutritional value.