By-product Feeds for Horses: [Ingredients Guide]

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:

Variability

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.

Allergies

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]

While horses can have food sensitivities, equine food allergies are rare and difficult to diagnose. More research is needed to investigate the relevance of food sensitivities in equine feeding management. ^[8]

Common By-Product Feeds for Horses

Feed labels sometimes contain by-product ingredients with obvious names like “grain by-products.” But some horse owners may feed a formula containing by-products with less obvious names.

Here’s a review of some of the mostcommon by-product feeds in equine diets.

Beet Pulp

Beet pulp is a familiar feed room staple. This by-product is the fibrous material that remains after sugar beets are processed for sugar extraction. ^[9]

Nutritional Profile

Beet pulp is an excellent source of soluble fibre and energy. With relatively low protein content, it is often used as a feed additive for horses that need additional calories or supplemental roughage when forage supply/intake is low. ^[9]

Nutrition Composition of Dry Beet Pulp

Values are provided on a dry-matter basis. View the complete profile for dry beet pulp in the Feed Bank. ^[7]

Benefits

Beet pulp is the by-product of extracting sugars from sugar beets. This makes it relatively low in sugar and suitable for horses that need a low-starch diet. ^[9]

The following additional benefits make it a common feed for horses:

• Highly palatable: Suitable for horses with dental problems ^[10]
• Supports hindgut health: Readily fermentable to support beneficial microbes in the hindgut. It can be used to support hindgut function in horses prone to colic or gut dysbiosis, hard keepers and senior horses ^[11]
• High water-holding capacity: Supports hydration in performance horses, such as endurance horses ^[12]

Considerations

Beet pulp often contains added molasses, which is another product of sugar beets. This improves palatability, but also increases the sugar and potassium content of the beet pulp.

Although low levels of molassed beet pulp are likely not harmful, it is best to feed unmolassed beet pulp if possible. ^[7]

Due to the high calcium and low phosphorous content, ensure that you feed beet pulp as part of a balanced diet. The ideal ratio of calcium to phosphorus in the total diet is 2:1. Beet pulp has a calcium-to-phosphorus ratio of roughly 10:1. ^[7]

Growing foals and lactating mares are most sensitive to calcium and phosphorus imblanaces. Their diets should be carefully balanced to support bone development and milk production.

Dried beet pulp is available in shredded or pelleted form. Although it can be fed dry, it is generally recommended to soak beet pulp to reduce the risk of choke and colic. ^[10][13]

How Much to Feed

Beet pulp inclusion in the diet can be fairly high without ill effects. However, issues with palatability and mineral balance may arise at high intakes.

Research studies feeding beet pulp at over 55% of the dry matter content of the diet show a decrease in feed intake. However, when it accounts for approximately 45% of the dry matter content, there are no changes in feed intake. ^[13]

A 50% inclusion level is roughly 5 kg (11 lb) on a dry matter basis. However, typical levels seen in equine diets are closer to 1 – 2 kg (2 – 4 lb) per day. ^[14]

Grain By-products

Grain by-products are widely available as remnants of the production of cereal-based flour and oils for human consumption.

Flour manufacturing uses the endosperm of the grain, which represents 80% of the grain kernel. The remaining portions are the bran and the germ, as well as the outer hull.

Oil extraction removes the fat leaving behind the components of the grain that are high in protein and fibre.

Bran

Bran is the hard outer layer of cereal grains removed by milling. Wheat bran and rice bran are two commonly fed brans in the equine diet. ^[15]

Nutritional Profile

Wheat and rice bran are a concentrated source of additional calories for horses owing to their high-fat content. ^[7]

Bran is generally high in phosphorus and low in calcium. Therefore, commercial feeds that include rice or wheat bran will generally balance the phosphorus content with other ingredients or added calcium.

Nutrition Composition of Rice Bran

Values are provided on a dry-matter basis. View the complete profile for rice bran in the Feed Bank. ^[7]

Benefits

Wheat and rice bran are palatable concentrates that add calories to the diet. Horses with high energy needs or those that do not tolerate added oil may benefit from wheat or rice bran.

Bran is a more palatable source of phosphorus than supplements such as monosodium phosphate.

Considerations

Due to the high NSC content, it is important not to overfeed wheat or rice bran, particularly to easy keepers or horses with equine metabolic syndrome.

These by-products are best added when the diet composition is well described, such as when there is a forage analysis that includes calcium and phosphorus levels.

Typical Inclusion Levels

It is recommended to work with an equine nutritionist when adding wheat bran or rice bran as individual feeds. This will ensure that the diet is well-balanced with an appropriate supply of calcium, phosphorus, and non-structural carbohydrates.

Our equine nutritionists typically add 300 – 1,000 grams per day of wheat or rice bran depending on the forage composition, other feeds in the diet, and the individual horse’s needs.

Meals

The by-products produced after oil extraction from cereal grains are commonly referred to as meals. Popular examples include soybean meal or canola meal. Others include wheat meal, copra meal, and corn gluten meal.

Nutritional Profile

The nutritional profile of grain meals differs based on the grain source and processing method used to remove the oil. Oils can be removed from seeds by solvent extraction or extrusion. Solvent extraction is the most commonly used method. ^[16]

Soybean meal is a common protein source in equine diets and animal feed. ^[1] It is added to complete feeds and fed as a single ingredient to boost the protein content of the diet.

Nutrition Composition of Soybean Meal

Below is a typical nutritional profile of soybean meal following solvent extraction of oil. Values are provided on a dry-matter basis. ^[7]

Benefits

Although the nutritional profiles vary, meals are generally high in protein and low in fat. They are a great choice for horses that need extra protein without high-fat content.

Soybean meal is especially high in lysine, the most commonly limiting amino acid in equine diets. It also provides all other essential amino acids that the body can not make on its own.

Soybean meal is an excellent protein source for growing horses, and lactating and gestating mares.

Considerations

High-protein diets may be detrimental for some horses, particularly those with kidney disease or liver issues.

Feeding excess protein also contributes to the environmental footprint of horses by increasing nitrogen excretion.

Horses in stalls will also be exposed to higher ammonia in the air when overfed protein. This can contribute to respiratory issues such as heaves or asthma. ^[17]

Typical Inclusion Levels

When changing your horse’s diet, work with an equine nutritionist to ensure you provide a well-balanced ration.

Soybean meal, or other high-protein feeds, are typically added to the extent that additional protein is needed in the diet.

Hulls

Hulls are the outer casing that holds grain kernels or soybeans. These are high in fibre and can be fed on their own as a pelleted feed or as a component of a complete feed.

Some may associate hulls with inexpensive filler ingredients, but these by-product feeds can be useful additions to the equine diet.

Nutritional Profile

Various hulls are available as by-products of oil, flour, or meal production. Examples include soy hulls, oat hulls, almond hulls and sunflower hulls.

Hulls can be used as a feed ingredient, supplemental feed, or pelleting agent. Hulls are generally high in structural carbohydrates (fibre) and low in non-structural carbohydrates (sugar and starch).

Nutrition Composition of Oat Hulls

Below is a typical nutritional profile of oat hulls, with values provided on a dry-matter basis. ^[7]

Soybean hulls are typically higher in protein (~12% crude protein) and lower in NSC (~5%) than other hull products.

Benefits

These high-fibre by-products can be added to any equine diet. Structural carbohydrates support the beneficial microbes of the hindgut, and may improve gut issues such as dysbiosis or fecal water syndrome.

Hulls are low in protein and energy. They are suitable for the diets of maintenance horses, easy keepers, and those with metabolic disorders.

Unlike other grain by-products, hulls have a better calcium-to-phosphorus ratio (approximately 1:1.5) Their high water-holding capacity can also support hydration in performance horses. ^[12]

Considerations

High inclusion of hulls may not be suitable for horses with high energy or protein needs, such as performance horses, lactating and gestating mares or growing foals. ^[18]

Hulls are typically added in pelleted form for improved palatability.

Typical Inclusion Levels

The optimal feeding rate will depend on your horse’s needs, ingredient availability, and what else is in your horse’s diet.

In one study involving horses in moderate work, researchers replaced up to 40% of a commercial feed with soybean hulls without any ill effects. ^[19]

Similarly, a study in young mares showed no concerns when soybean meal was included at up to 28% of a complete feed (11% of the total diet). ^[20]

Wheat Middlings

Wheat middlings, also known as wheat mids, are a by-product of processing wheat to manufacture flour. Because of its natural binding properties, this ingredient often appears in pelleted formulas. ^[2]

Contrary to common belief, wheat middlings are not floor sweepings. Instead, this by-product contains the bran and germ of the cereal grain, which are rich sources of nutrients. ^[21]

Nutritional Profile

Benefits

Wheat midds are higher in protein and lower in starch than ground whole wheat. ^[2]

Considerations

As with cereal bran, the high-starch content must be considered when adding wheat midds to the equine diet. The calcium-to-phosphorus ratio also needs to be balanced by appropriate calcium sources. ^[7]

Typical Inclusion Levels

Wheat midds are rarely added as a single feed but are commonly included in complete feeds as one of the main ingredients.

Distillers Dried Grains

Distillers’ dried grains (also called brewer’s grains) are the by-product of grains used in distillery and ethanol production.

Cereal grains used in brewing include corn, wheat, and barley. After yeast fermentation and alcohol removal, the leftover dried grains are a high-protein, low-NSC energy source. ^[22]

Nutritional Profile

The nutritional profile of distiller’s grains can vary greatly between batches based on the relative proportions of grains and distilling methods used.

Nutrition Composition of DDG

The following nutritional profile is an average of roughly 5,000 distillers grains samples between 2004 – 2022. ^[23]

Benefits

DDG is a cost-effective feed additive where locally available. It is much higher in protein and lower in NSC than the original grains.

DDG has a similar energy content as oats but with lower starch and sugar. ^[24][25]

Considerations

The high variability between batches makes it difficult to formulate an accurate diet without a recent lab analysis. It is best fed as a component of a pelleted or complete feed, in which the batches of feed are frequently tested.

The lysine content of DDG (2% of crude protein) is lower than other protein sources, such as soybean meal (6% of crude protein). If DDG is included at more than 20% of dry matter intake, a supplemental lysine source may be required. ^[25]

The dried product is preferred because wet distiller’s grains may spoil easily depending on storage conditions. ^[25]

Typical Inclusion Levels

Research studies suggest DDG can be included at 10 – 20% of the dry matter intake for growing horses and 20 – 40% for older horses. ^[25]

Other By-Products for Horses

Citrus Pulp

Citrus pulp is a by-product that remains after extracting juice from oranges, lemons or limes. Depending on regional availability, this can be a cost-effective, low-protein fibre source for equine diets. ^[26]

Corn gluten feed and meal

Corn gluten feed and meal are produced from milling corn for syrup and starch. Gluten feed averages about 20% crude protein but offers relatively low lysine content. ^[27]

These corn by-products have variable energy levels, which can alter the digestible energy of the feed ration. ^[28]

Molasses

Like beet pulp, molasses is another by-product of the sugar industry. This sweet-tasting ingredient improves palatability and is safe to feed horses in small amounts. ^[4]

Whey

Whey is milk protein that is widely available because it is a by-product of cheese manufacturing.

Whey is a complete protein, providing all essential amino acids. It is commonly added to equine feeds as a palatable protein source.

Selecting Horse Feeds

Forage should provide the foundation of your horse’s diet. Before comparing horse feeds or considering by-products, ensure that you are feeding adequate amounts of appropriate, good-quality forage. ^[7][29]

Some horses may not need commercial feed, but vitamin and mineral supplementation is always necessary to fill the nutritional gaps in forages. ^[29]

You can evaluate your horse’s diet by calculating the nutrients provided by your horse’s feeding program and comparing it to the NRC’s Nutrient Requirements of Horses. ^[7]

If you want to learn more about the ingredients in your horse feed, submit your horse’s diet for analysis and set up a free consultation with one of our equine nutritionists.

Summary

• By-product feeds are common ingredients in equine diets that have been safely fed to horses for decades.
• Popular by-product ingredients contribute valuable nutrients to commercial horse feeds while keeping the formulas affordable for horse owners.
• Some by-products such as beet pulp and rice bran are commonly fed as added components of the diet.
• No matter what ingredients make up your horse feed, a balanced diet ensures that your horse gets the amino acids, vitamins, and minerals he needs.