Soybean Meal for Horses

Soybean meal can be a good source of protein for horses but cannot serve as a horse’s entire feed ration. An equine nutritionist offers alternatives and additions to soybean meal in horses’ diets.

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soybean meal
Soybean meal can be one component of a balanced ration for horses. | Getty images

Q: A new vet came to our barn recently to check our horses’ teeth and recommended a soy meal diet instead of grain. What is your input on soy meal as a staple for horses?

A:  Soybean meal is an excellent source of protein for horses due to its high-quality amino acid profile. Specifically, it is rich in the essential and “first limiting” amino acid lysine and other essential amino acids methionine and threonine. For this reason, many premium commercial horse feed formulas include it as an ingredient.

Soybean meal serves as a valuable staple in many horses’ diets and one component of an overall balanced ration. However, by itself soybean meal is not balanced and should not serve as a grain replacement. People tend to use the term “grain” differently; some use it to describe any type of commercial feed that comes out of a bag. Others use it to describe a true grain, such as straight oats or barley. Regardless of how your new veterinarian used the term, soybean meal is not a grain replacement because it is missing many key essential vitamins and minerals, is low in fiber, and it is not a good energy source. Depending on what your horse’s “grain” ration currently comprises, replacing it with straight soybean meal could lead to a nutrient deficiency, weight loss, or both.

It might be helpful to take a step back and ask your new vet to elaborate on this recommendation. Are they concerned about the horses’ weight and are recommending fewer calories? Are they concerned the current grain is missing amino acids? Is it based on something else? From there, you can determine what changes, if any, you need to make to your horse’s current ration.

If your horse is an easy keeper (maintains good body condition on a forage-only diet) and/or needs to lose weight, the veterinarian might be recommending you replace an energy-dense grain or fat-added commercial feed with soybean meal to reduce calories but still supply essential amino acids in the diet. If this is the case, a better strategy might be to feed a ration balancer, or a feed product with a low feeding rate (typically 1-2 pounds per day for a 1,000-pound horse) specifically designed to fill in the nutritional gaps of a forage-only diet. Ration balancers supply essential amino acids, vitamins, and minerals without adding unnecessary calories. Most ration balancers contain a significant amount of soybean meal, but they also contain added nutrients that will create a balanced diet when fed along with good-quality forage. A ration balancer is a better option than straight soybean meal because it will be more palatable for the horse and will contain added essential nutrients soybean meal lacks.

If your horse needs to build topline or lacks muscle, your vet might be recommending soybean meal to introduce better-quality protein into the diet. If this is the case, then soybean meal will certainly accomplish that goal, but you must feed additional ingredients to supply calories (if needed) and essential nutrients (always needed). This can be done much more effectively either by feeding a ration balancer paired with additional energy-dense ingredients or by feeding a high-quality concentrate feed that contains the essential amino acids, nutrients, and energy needed to help support your horse’s current life stage, body condition, and workload. This is especially critical for performance horses that need to build topline, because dietary protein is only one piece of the puzzle; it takes the right amount of high-quality protein along with adequate calories and essential vitamins and minerals paired with regular and correct exercise to properly build muscle over the topline. A premium commercial feed formulated for performance horses checks all the nutritional boxes, and there is no guesswork involved when trying to create a balanced ration if you follow the manufacture’s feeding directions based on your horse’s body weight and exercise level.

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Written by:

Kelly Vineyard, MS, PhD, is a senior nutritionist in equine technical solutions with Purina Animal Nutrition. She consults with veterinarians, professional riders, and horse owners across the United States and is directly involved with new product innovation, research, and technical support at Purina. Vineyard earned her BS in animal and dairy sciences from Auburn University and her MS and PhD in animal sciences from the University of Florida. Her doctorate research focused on the effects of omega-3 fatty acid supplementation on immune function in horses. Vineyard is a frequent lecturer on equine nutrition topics, with expertise in omega-3 fatty acids, immune function, and performance horse nutrition. She is an avid dressage rider and is proud to have earned her USDF bronze and silver medals on an off-track Thoroughbred.

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