By-product ingredients are a fixture in equine diets, either as components of a complete feed or as concentrates added into the diet on their own.

Although the term “by-product” may carry a negative connotation, these feeds are often high-quality, cost-effective options to add energy, protein or fibre to your horse’s diet.

By-product feeds usually have a better nutritional profile for horses than their original source. For example, beet pulp is a great source of soluble fibre and contains much lower starch and sugar than whole sugar beets.

This article will discuss by-product ingredient sources, explore their value in the equine diet, and review key considerations when adding a by-product feed to your horse’s diet.

By-Products in the Equine Diet

By-products are secondary products created during the manufacturing of something else. Many by-products used in horse feed are secondary products created by processing grains and other plants for human consumption.

Commodities associated with by-products for horses include flour, cooking oils, sugar, syrup, and alcohol. [1] For example, wheat middlings are a by-product of wheat flour production. [2]

Are By-Products Safe for Horses?

Although not all by-products of human food processing are suitable for horses, many by-product ingredients have been used in equine diets for decades. [1]

By-products have been extensively studied as nutritional components of livestock feeds but have been studied less in horses. [3]

If you have concerns about specific ingredients in your horse’s feed, you should always consult with an equine nutritionist and your veterinarian.

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Using By-Product Feeds

By-products are useful to add to your horse’s diet when forages are not adequately meeting their needs. However, there are factors to consider when choosing by-product feeds, including:


Like forages, commodities such as corn, oats, barley, and sugar beets will have natural variations in their nutritional composition based on growing and harvest conditions.

The nutritional profile of the by-products can also vary based on the processing method. There can be significant variability in products from batch to batch.

This can be a concern if mineral concentrations vary enough to lead to an imbalanced diet.

Commercial feeds sourced from reputable companies undergo routine testing to ensure their products are within certain specifications. Only purchase feeds, by-product ingredients and supplements from reputable brands that provide a guaranteed analysis for their products.

Inclusion level

Not all by-products are suitable for all horses. For example, metabolic horses and easy keepers should avoid feeds with high non-structural carbohydrate content.

Limit the amount of high starch ingredients in your horse’s diet to reduce the risk of digestive issues, such as gastric ulcers and hindgut dysfunction. ‘Hot’ behaviour may also be attributed to high starch diets. [4][5]

You can get a rough idea of the relative inclusion of by-products in a complete feed by looking at the ingredient list. Most regulations require that feed tags list ingredients in descending order based on inclusion rates.

Storage & Handling

Some by-products are more prone to becoming moldy or going rancid. By-products with high moisture content, such as wet distiller’s grains, need to be stored in a cool, humidity-controlled environment to reduce the risk of mycotoxins impacting your horse’s health. [6]

By-products high in fat, such as rice bran, may become rancid due to lipid peroxidation. Stabilized products that are heat-treated to reduce lipase activity are preferred. This process makes the fat molecules more stable to reduce rancidity.


Some horse owners are concerned about feeds that contain soy, wheat, or corn products. These ingredients are usually safe for most horses so long as they are included in a balanced ration that meets the NRC Nutrient Requirements of horses. [7