Q.I recently adopted an off-track Thoroughbred (OTTB) mare. She needs to gain weight especially since winter is coming. The problem is, she seems to be a very picky eater and not particularly interested in the hay or pellets I’m feeding her. I need suggestions on how to quickly get weight on her.

—Michelle, Seattle, Washington

A.Dealing with an underweight horse who is also a picky eater can be a stressful situation. Obviously, if the horse were less picky about what they eat, it would go a long way to helping solve the weight issue. So, trying to figure out why she is picky is a good place to start.

Step 1: Identify and Fix Medical Issues

While she might simply not like the form or type of food being offered, it is quite possible that some kind of gastrointestinal discomfort could be to blame. As such, determining the root cause of the pickiness and fixing it can be a large component of success.

Gastric ulcers are a common problem with racehorses due to the high demands of training as well as the high-starch diets they are often fed. Horses with gastric ulcers often go off feed, especially grain, and are generally unthrifty in appearance. It would be worth having your veterinarian scope your horse to determine whether there are, in fact, gastric ulcers present and ,if so, what type. Knowing where the ulcers are within the stomach allows the most effective treatment protocol to be selected.

Hindgut disturbance is another common problem. This can develop when large amounts of high-starch concentrate are feed are fed in two, maybe three, meals a day. When more than about 5 pounds of high-starch feed are fed at one time, some will likely escape foregut digestion resulting in very easily digestible starch entering the hindgut where it is rapidly fermented. This rapid fermentation results in gas production and a gradual acidification of the hindgut that disrupts microbial fermentation of forage. Horses might not only be less inclined to eat grain in this situation, but also could turn their noses up at hay.

The use of a hindgut buffer can help rectify the acidification of the hindgut and allow the resident fiber utilizing bacteria a chance to gain a foothold. Providing a prebiotic such as Saccharomyces cerevisiae or Saccharomyces boulardii might also be beneficial in helping to establish a healthy hindgut and improve feed utilization.

There are a good number of supplements on the market that claim to help support gastric health and some of these might also be useful. Try to find research-backed products or those with ingredients that have been shown by research to help reduce the severity or occurrence of gastric ulcers.

Step 2: Look at the Diet

As to overall diet, start by feeding as much good-quality forage as the mare will eat. Providing up to about 30% of the forage as alfalfa will help increase the calories bring provided and the higher protein might help maintain muscle mass. Fresh-off-the-track OTTBs have very high lean muscle mass and as a result could need considerable calorie intakes despite not working particularly hard. Utilizing some alfalfa in the ration can help with this as alfalfa is generally higher in calories-per-pound than most grass hays. Additionally, few horses turn their noses up at alfalfa and the high calcium content is a good stomach acid buffer.

Your OTTB likely needs a source of more concentrated feed than hay alone. Performance feeds and senior feeds can be a good choice. Keep in mind that at the track she was likely fed textured feeds and or oats rather than pellets. So, initially at least, pellets might not be as appealing in part because they are unfamiliar compared to textured feed.

Textured feeds can be a great choice not just because of the familiar form but also because there tend to be more high fiber high fat options within the textured feeds versus pellets. High-fat and -fiber feeds are a great way of adding considerably more calories without feeding as much starch. They utilize fermentable fibers such as beet pulp and soy bean hulls as well as fat sources such as vegetable oils, flax, and rice bran. The result can be a high-calorie, low-starch and -sugar feed that is appealing even to the picky eater.

Many senior feeds fall in to this category and tend to be easily digestible and well-fortified. Look for high-fiber (a minimum of 15-20%), high-fat (8% or more) options. Follow the manufacturer’s feeding guidelines for instructions on how to feed. Keep amounts per meal at no more than 5 pounds and try to divide the concentrate in to as many small meals as possible.

The Bottom Line for Underweight, Picky Horses

Weight gain will likely be a slow process, so be patient. You should start to see an improvement within about a month. If you do not get adequate weight on her before winter, consider blanketing to help conserve energy stores for body weight maintenance and gain rather than expending calories on staying warm.