This is the second article in the “Fix It With Feed” series. Check back every Wednesday for more articles on nutrition and how it affects performance.

Some horses have a problem many of us envy—they have trouble gaining and maintaining enough weight. Whether it’s a performance horse that drops condition due to a heavy workload, or it’s an off-the-track Thoroughbred that just can’t lose its “racetrack fit” physique, it can be a frustrating problem for a caretaker.

The answer is pretty simple—add more calories to the horse’s diet. But bags of horse feed aren’t like human food; they don’t have calories or digestible energy listed on the tag. “Digestible energy is a calculated number based on the fat, fiber and protein of the ingredients,” said Tania Cubitt, Ph.D., a nutritionist with Performance Horse Nutrition LLC. “Energy is never on the tag because there are several digestible energy calculations used and the industry has not settled on one standard calculation. Energy is the one thing we base all our feeding on, but we still don’t really measure it properly.”

Even though there is no calorie guide on the feed tag, there are still some good guidelines to follow that go beyond feeding more at every meal. You also need to keep in mind that putting weight on your horse should be a gradual, slow process.

“If you start with a horse with a body condition score of 4 and want to make it a 5, that’s going to take adding about 40-45 pounds—based on an 1100-pound horse—and you can safely do that over a 60-day period. Weight gain is a slow process,” Cubitt said.

1. Take A Good Look At Your Hay

Forage—hay and pasture—is the foundation of the horse’s diet. The first thing Cubitt suggested to improve a horse’s condition is providing the best quality forage possible and allowing a horse unlimited access to it.

Grand prix show jumper Scott Keller takes advantage of the Kentucky bluegrass as long as weather permits. “With a hard keeper, I’ve found one of the most important factors [in keeping weight on your horse] is giving ample turnout time. It obviously boosts caloric intake, but it relaxes them, and it’s a sort of mental detox,” said Keller, whose Townsend Springs Farm is located in Paris, Ky. “As a substitute, when we’re at shows, I feed a lot of orchard grass hay.”

“If you’re feeding a first cut timothy that’s pretty stalky, then immediately I’d at least try and find a second cutting timothy or a hay that has a lot more leaf on it, a better quality hay,” Cubitt said. “Alfalfa’s the perfect choice in the right circumstance. It’s much higher in calories, and the additional protein it has will help build muscle. It won’t make your horse crazy. Protein does not make your horse crazy.”

Cubitt’s ideal for the high performing athlete or a horse struggling to maintain weight would be feeding 50 percent alfalfa and 50 percent grass hay, but the quality of the hay is paramount. Alfalfa availability is regionally dependent, and many horses on the West Coast eat 100 percent alfalfa because grass hay is hard to come by.

It’s also possible to replace mixed grass/alfalfa hay with a pound-for-pound substitute of alfalfa cubes or pellets.

“With pellets, it’s not always necessary to soak them. It’s really not necessary to soak cubes either, but sometimes the cubes can be hard. It never hurts to soak anything, because it also gets additional water into the horse,” Cubitt said.

2. Feed A Stable Concentrate Ration

Feed company scientists put a lot of research into formulating their concentrates so that if you feed according to the recommendations on the bag or tag, your horse receives the nutrients he needs in the correct balance. Thus, it isn’t a great idea to control your horse’s weight by adding or subtracting a scoop of feed.

Cubitt recommends feeding according to the manufacturer’s recommendation. If the feed bag suggests 4 to 8 pounds based on the weight of your horse, and you only feed 2 pounds, your horse is getting half the vitamins and minerals he’s supposed to. However, if you feed him 12 pounds, then you’re creating expensive manure full of vitamins and minerals, when really you only wanted to add calories.

For a performance horse that expends a fair amount of energy on a regular basis, Cubitt recommended choosing a high-fat, high-fiber feed. “If you’re feeding a sweet feed that’s 3 or 4 percent fat, I’d try to find a high-fiber feed with a higher fat percentage—10 to 14 percent fat and high in super fibers such as beet pulp, soy hulls and alfalfa meal. If you are already feeding a high fat and fiber feed and you’re splitting the horse’s ration into three or four meals a day (equine digestion is most efficient this way), then the next step is to add a high fat, top dress supplement such as vegetable oil,” Cubitt said.

“My general thesis is that I can generate extra weight with grass and hay, but I use grain to maintain fitness,” Keller said. “I prefer a high-quality, low sugar feed.”

Keep in mind that the horse is a grazing animal, with a digestive system designed for small amounts of food ingested constantly. “I never like to feed more than 3 to 5 pounds in any one meal, and if I need to be feeding a significant amount of grain, like 12 pounds a day, I would definitely split the meals into three or four feedings a day. You should feed at least three meals a day if you really want to put weight on your horse,” Cubitt said.

Once the horse achieves the desired body condition, the added calories can be decreased to a maintenance level. “I can put in or take out oil or rice bran or beet pulp, and all it’s adding is extra calories. Then I can decrease that or take it away when the horse gets to an ideal weight,” Cubitt said.

However, if your horse turns out to be an easier keeper than you expected, you may need to change to a feed that provides more nutrients in fewer calories. Remember, if you go below the manufacturer’s recommendations, your horse won’t receive the vitamins and minerals he needs.

3. Add Calories In An Educated Manner

There are many different ways to add calories to a horse’s diet. But it’s important to consider which one will give you the most bang for the buck, or the most digestible energy (calories) per pound.

*Additional lbs/day is calculated on an 1100-pound horse and how much extra (over and above current feed) you would need to feed over a 60-day period to gain 1 condition score

The 2007 National Requirements for Horses suggested that it takes 40 to 45 pounds of gain to change a horses body condition score by 1 unit (based on an 1100 pound horse). Therefore a horse with a body condition score of 2 would need to gain around 120-135 pounds to increase its condition score to a 5. This would take around six months to achieve and would require a very energy dense feeding protocol.

Maintenance energy requirements for an average 1100lb horse are approximately 16.7 Mcal/d.

Beet pulp is one of the most popular and traditional things to add to a horse’s ration to gain weight. “Beet pulp is a good option because it’s a highly digestible fiber, but if I need to get some serious weight on a horse, I have to feed a lot of additional beet pulp to get there,” Cubitt said. Beet pulp only has 1.27 megacalories per pound. Rice bran has a slightly higher amount of digestible energy, at 1.5 megacalories per pound.

Cubitt’s top choice for adding calories is simple vegetable oil. “There are a lot of different ways to get to the same end point of an ideal weight. If you have all the time in the world, yes, feed beet pulp. It’s going to work, but it’s not going to work as quickly as feeding oil. Rice bran will put weight on a horse, but also at a slower rate. That doesn’t mean it’s wrong.

“My preference is for vegetable oil because it’s easier and adding less bulk. A lot of hard keepers are also really finicky eaters, which is why they’re thin. They’re too busy looking around to eat a huge meal. If you can’t get them to eat the volume of feed you’re already feeding, it’s going to be even harder to get them to eat a few more pounds of wet beet pulp,” she continued.

Oil provides 4.6 megacalories per pound, packing the biggest digestible energy punch of all the additives. Cubitt prefers vegetable oil or soybean oil.

“Whatever your fat source is, whether it’s a powdered fat source, an oil, or a fat concentrate supplement, you’ve just got to make sure things stay in balance,” said Emily Lamprecht, a scientist at the Cargill Innovation Lab. “Anytime you add something to an already balanced diet, it shifts the nutrient ratios, so be sure that when you’re adding, everything else is still in check.”

Corn oil is a well-known feed additive, but it has recently gotten bad press because it has low amounts of Omega 3 fatty acids and high amounts of Omega 6 fatty acids.

“Both Omega 3s and Omega 6s are important,” said Cubitt. “Omega 3s are anti-inflammatory. For a horse that’s heavily exercising and in somewhat of an inflamed state because of all that exercise, then we really would prefer to find a fat source that’s higher in Omega 3s than corn oil.”

“Soybean oil and canola oil are higher in Omega 3 fatty acids. Flaxseed oil is the highest plant form of omegas 3 fatty acids. But for sheer weight gain, it’s expensive,” Cubitt continued.

Cubitt advised adding 1 to 2 cups of oil to the horse’s daily diet and introducing the amount gradually over 10 to 15 days. “I don’t usually recommend any more than 2 cups of oil additionally on top of whatever they’re getting fed currently. At that point, palatability goes down,” she said.

There are powdered supplements on the market that add calories to the horse’s diet, but Cubitt suggested reading the fine print on their packaging. “You have to look at the fat content—if it’s 20 percent, then you’re better off going to the grocery store and buying vegetable oil, which is 99.9 percent fat. A lot of them are rice-bran based, and rice bran is only 20 percent fat. They will put weight on your horse, but they’re very expensive and usually the feeding rate is quite low, so they’ll work slowly,” she said.

There are powdered supplements made of hydrogenated vegetable oil with 99 percent fat, and they’re especially useful if a horse declines to eat oil in their feed.

4. Keep It Simple

When you’re desperate to put weight on your horse, it’s tempting to pile on every possible solution and complicate the diet too much. In reality, a simple strategy and a lot of patience will pay off in the end.

“Some people add a couple of pounds of beet pulp and a couple of pounds of rice brain and then they add a squirt of oil, and whoa, that’s a lot. I like to keep it simple, because naturally the horse is supposed to eat grass and not much else,” said Cubitt.

“We don’t use supplements [for weight gain]. The right grain and hay normally works well for our horses whether they’re at home or on the road,” agreed Keller.

Read Part 1: You Don’t Need A Ph.D. To Puzzle Out Protein