What's In The Bag?

Is the data on that tag stitched to the feed bag effective for predicting the performance of the feed? While there are some limitations, the data are useful not only for evaluation, but also to help decide which feed to buy. Furthermore, the feed company must meet the guarantees on the feed tag or face fines.

In fact, testing of guaranteed feeds was designed to prevent fraud more than to help farmers decide which feed to buy. In 1857, the Connecticut State Agricultural Society decided to hire a chemist to analyze fertilizer because many farmers complained that the fertilizer companies were promising miraculous fertility, but they only delivered worthless mixtures. The Civil War interrupted the process, but the testing program and publication of the results led to improved fertilizers. After the war, the analysis of other products was initiated. Many state experiment stations were developed after the Civil War, and by 1899, at least 28 experiment stations were required to inspect seeds, fertilizers, feeds, and foods.1

As with fertilizers, many early mixed feeds were adulterated with worthless or low-quality ingredients. The Connecticut Agricultural Experiment Station (Bulletin 130) in January 1900 reported that the oat feeds that were claimed to provide protein to supplement corn and hay diets were not properly manufactured. According to the report, "The products contain less protein than good corn and as much woody fiber as good hay."

In 1904 Bulletin 145 of the Connecticut Agricultural Experiment Station reported the analyses of four horse feeds. Three of the four feeds met the manufacturer's guarantee, but the report concluded, "The prices of the ready-mixed horse feeds, ranging from $20 to $30 per ton, are quite out of proportion to their feeding value."

State or federal agencies now conduct feed analyses. They no longer comment on the economic value of feeds, but they continue to help prevent fraudulent practices. Furthermore, because of feed regulations, feed tags provide information that can help you select the right feed. There are many more feed options now than in the early 1900s; few horse owners purchased mixed feed in the late 1800s and early 1900s. Now, according to a report by the National Animal Health Monitoring System (NAHMS), 90% of horse owners buy some commercial feeds,2 and many feed companies are competing for the horse owner's business.

Animal Feed Regulation

Each state animal feed regulatory agency has a representative who's also a member of the Association of American Feed Control Officials (AAFCO). AAFCO has no regulatory authority on its own, but because its members are state and federal regulators, recommendations are usually adopted as-is by the states. AAFCO states: "The most important aspect of feed regulation is to provide protection for the consumer as well as the regulated industry."3

AAFCO regulations state:

Commercial feed, other than customer-formula feed, shall be labeled with:

  • Product name and brand name if any;
  • Purpose statement (the use intended);
  • Guaranteed analysis;
  • List of ingredients;
  • Directions for use and any warning or caution statements; and
  • Name/address of the manufacturer.

AAFCO requires the following nutrient guarantees:

Guaranteed Analysis for Equine Complete Feeds and Supplements (all animal classes of foal, mare, breeding, and maintenance):

  • Minimum percentage of crude protein;
  • Minimum percentage of crude fat;
  • Maximum percentage of crude protein;
  • Minimum and maximum percentages of calcium;
  • Minimum percentage of phosphorus;
  • Minimum amount of copper in parts per million (ppm, which is equal to one milligram per kilogram);
  • Minimum amount of selenium in ppm;
  • Minimum amount of zinc in ppm; and
  • Minimum amount of vitamin A, other than the precursors of vitamin A, in international units (IU) per pound (if added).

Guaranteed analysis for equine mineral feeds (all animal classes of foal, mare, breeding, and maintenance):

  • Minimum and maximum percentages of calcium;
  • Minimum percentage of phosphorus;
  • Minimum and maximum percentages of salt (if added);
  • Minimum amount of copper in ppm;
  • Minimum amount of selenium in ppm;
  • Minimum amount of zinc in ppm; and
  • Minimum amount of vitamin A, other than the precursors of vitamin A, in IU per pound.

Required Minerals

The horse needs at least 21 minerals in his diet, but only five have to be listed on the tag. These five are the ones usually most likely to be problematic.

Calcium and phosphorus are important because of their roles in bone formation. The ratio of calcium to phosphorus is important because excessive phosphorus can inhibit calcium utilization. Therefore, it is recommended that the total diet contain at least as much calcium as it does phosphorus. Of course, if the forage is a legume and contains a high amount of calcium, the concentrate can contain more phosphorus than calcium and the total diet will still provide adequate calcium.

Severe calcium deficiency resulting in "bighead disease," a condition in which calcium is withdrawn from the skull and replaced by fibrous connective tissue, was quite commonly reported in the late 1800s and early 1900s, but it is rare today. However, even a marginal deficiency of calcium can cause bone problems and lameness.

Copper is a requirement for the formation of bone, cartilage, and elastin (a protein that is similar to collagen and is the chief constituent of elastic fibers); a deficiency can result in osteochondrosis. Zinc is required for several enzyme systems and bone formation.

Selenium is required for normal muscle development--foals of mares fed low-
selenium diets develop white muscle disease (nutritional muscular dystrophy). The foals become weak, have difficulty nursing, and can die of inhalation pneumonia because they can't swallow properly.

The requirements for your animals depend on many factors such as function, age, climate, and activity level. The content of any nutrient that is listed on the tag can help you decide which feeds will be adequate for your situation.

Information on equine nutritional requirements can be found in the National Research Council (NRC) publication Nutrient Requirements of the Horse 4 and in many extension publications and books. If you have your forage tested for nutrients and can estimate intake, then you can determine what the animals are obtaining from the forage. You can then calculate how much of each nutrient is needed from the grain. Your feed dealer can provide information as to which type of feed is needed to supply the nutrients not provided by your forage.

What's on the Tag

The ingredients must be listed on the tag, but they do not have to be listed individually. Many companies use collective or generic names (see "Collective Feed Ingredient Terms" on page 90). The collective terms enable companies to make adjustments in feed ingredients as dictated by economics and/or availability. The process is called "least cost formulation." The ration still must meet its guaranteed nutrient content, but the tag does not need to be changed if the new ingredients are within the collective terms.

Collective terms used for horse feeds include roughage products, plant protein products, processed grain by-products, forage products, molasses products, and grain products. Some owners feel that ingredient variation allowed by the use of the least cost formulation might cause feed refusal if the diet is radically changed, and they prefer to buy rations that have a consistent formula. Rations with a consistent formula usually list feed ingredients individually.

Even when the ingredients are listed individually, however, there is no indication of quality. For example, light-weight oats might weigh only 28 pounds per bushel and contain a high level of fiber. Heavy-weight oats might weigh 38-40 pounds per bushel and contain a low fiber content.

Limitations of the Feed Tag

Energy content--One limitation of the feed tag is the lack of information on the energy concentration of the feed. Digestible energy (DE) is the system used by the NRC to describe the energy content of feeds and the energy requirements of horses. Digestible energy content of a feed is determined by feeding a carefully measured amount of feed at the same rate per day to a horse for several days and collecting feces. The calories in feed and feces are determined; total caloric intake minus caloric content of the feces is the digestible energy. The digestible energy content cannot be determined by a simple laboratory test; thus the regulatory agencies cannot verify any energy claims. Therefore, information about energy content is not required on the tag.

Crude fiber can be used as a general guide to the energy content--the higher the crude fiber content, the lower the energy. But all fibers are not equal. Some crude fiber (such as that in beet pulp, for example) provides more energy than the fiber in hay.

Fat content is also an indicator of energy content. Fat contains more than twice as many calories per pound than starch; therefore, replacing grain with fat increases the energy content of the diet.

Many companies will provide estimates of the energy content of the feed if requested. When comparing values from various companies, be certain they are expressed in the same method. For example, some companies use Mcal/kg and some use Mcal/lb. To convert Mcal/lb to Mcal/kg, multiply by 2.2.

Protein Value--The protein content on the tag is listed as crude protein, which is the same measurement used by the NRC to express requirements.

One limitation is that protein content does not indicate protein quality. Amino acids are the components of protein, and most mammals require at least 10 different amino acids in the diet; however, little research on equine amino acid requirements has been done. Some animals--such as ruminants--can derive amino acids from the bacterial activity in the rumen. The horse has a large bacterial population in the cecum and colon, but the amino acids produced by the bacteria located there are of limited use to the horse because they cannot be effectively absorbed.

Requirements have been suggested for the amino acids lysine and threonine, but only lysine requirements have been established by the NRC. These requirements are listed because lysine is the amino acid that is most likely to be inadequate in the equine diet. Recent work has come up with estimated requirements for threonine.

The amino acid contents of the protein source can vary greatly. For example, soybean meal is a much better source of lysine than cottonseed meal or linseed meal. According to the NRC, soybean meal might contain 44% protein and 2.87% lysine, whereas cottonseed might contain 41% protein but only 1.68% lysine. Feed companies can provide the content of lysine and threonine if requested.

So, although the feed tag provides very useful information that can prevent fraud and help you select and predict the effectiveness of the feed, there can be considerable differences between feeds even though they have similar tags.

Furthermore, there is little information that can be used to predict if horses will eat the feed for a prolonged period because the nutrient sources can be changed without changing the label, thus changing the palatability of the feed to a particular horse.

If the company that manufactures the feed believes in quality control, use of scientific knowledge, and integrity, the feed tag can be very useful to select the feeds best for your situation.


1 Kerr, N.A. The Legacy. Missouri Agricultural Experiment Station, University of Missouri-Columbia, 47, 1987.

2 Part III: Management and Health and Horses. National Animal Health Monitoring System (NAHMS). Equine Survey, 1998.

3 Official Publication Association of American Feed Control Officials Incorporated. Association of the American Feed Control Officials, 2002. www.aafco.org.

4 National Research Council. Nutrient Requirements of Horses, 5th Edition. NRC-NAS, Washington, DC, 1989. www.nap.edu/books/0309039894/html/.


Basics of Feeding Horses: Reading the Feed Tag. Nebraska Extension Service. www.ianr.unl.edu/pubs/horse/g1403.htm.

Reading Feed Tags. The Ohio State University. http://ohioline.osu.edu/b762/b762_14.html.

Feed Tag Information for Commercial Horse Feeds. Oklahoma State University. www.ansi.okstate.edu/exten/horses/F-3919.PDF.


The Association of American Feed Control Officials (AAFCO) uses the following collective terms to refer to collections of similar ingredients.

Roughage products can include one or more of the following:

  • Almond hulls, ground
  • Apple pectin pulp, dried
  • Apple pomace, dried
  • Bagasse
  • Barley hulls
  • Barley mill by-product
  • Beet pulp, dried
  • Buckwheat hulls
  • Citrus meal, dried
  • Citrus pulp, dried
  • Citrus seed meal
  • Corncob fractions
  • Cottonseed hulls
  • Flax straw by-products
  • Husks
  • Malt hulls
  • Oat hulls
  • Oat mill by-product
  • Oat mill by-product, clipped
  • Peanut hulls
  • Rice hulls
  • Rice mill by-product
  • Rye mill run
  • Soybean hulls
  • Soybean mill feed
  • Soybean mill run
  • Sunflower hulls
  • Straw, ground
  • Tomato pomace, dried

Processed grain by-products can include one or more of the following:

  • Brewers' dried grains
  • Buckwheat middlings
  • Condensed fermented corn
  • Condensed distillers' solubles
  • Corn bran
  • Corn flour
  • Corn germ meal
  • Corn gluten feed
  • Corn gluten meal
  • Corn grits
  • Distillers' dried grains
  • Distillers' dried grains/solubles
  • Distillers' dried solubles
  • Grain sorghum germ cake
  • Grain sorghum germ meal
  • Grain sorghum grits
  • Grain sorghum mill feed
  • Hominy feed
  • Malt sprouts
  • Oat groats
  • Oat meal, feeding
  • Pearl barley by-product
  • Peanut skins
  • Rice bran
  • Rice polishings
  • Rye middlings
  • Sorghum grain flour
  • Wheat bran
  • Wheat flour
  • Wheat germ meal
  • Wheat germ meal, defatted
  • Wheat middlings
  • Wheat mill run
  • Wheat red dog
  • Wheat shorts

Forage products can include one or more of the following:

  • Alfalfa meal, dehydrated
  • Alfalfa hay, ground
  • Alfalfa meal, sun-cured
  • Coastal Bermuda grass hay
  • Corn plant, dehydrated
  • Dehydrated silage
    (ensilage pellets)
  • Flax plant product
  • Ground grass
  • Lespedeza meal
  • Lespedeza stem meal
  • Soybean hay, ground

Grain products can include any of the normal forms such as whole, ground, cracked, screen-cracked, flaked, kibbled, toasted, or heat-processed:

  • Barley
  • Corn
  • Grain sorghum
  • Mixed feed oats
  • Oats
  • Rice
  • Rye
  • Triticale
  • Wheat

Molasses products can include one or more of the following:

  • Beet molasses
  • Beet molasses, dried product
  • Beet pulp, dried, molasses
  • Cane molasses
  • Citrus molasses
  • Condensed molasses
  • Condensed solubles
  • Fermentation solubles
  • Molasses, distillers
  • Molasses, distillers, dried
  • Molasses yeast condensed
  • Solubles
  • Starch molasses

Plant protein products can include one or more of the following:

  • Algae meal
  • Beans, dried
  • Canola meal
  • Coconut meal
  • Cottonseed cake
  • Cottonseed flakes
  • Cottonseed meal
  • Cottonseed meal, low gossypol
  • Cottonseed, whole
  • Linseed meal
  • Peanut meal
  • Peas
  • Rapeseed meal
  • Safflower meal
  • Soybean feed
  • Soybeans, ground
  • Soybean, heat-processed
  • Soybean meal
  • Soybean meal, kibbled
  • Soy flour
  • Soy grits
  • Soy protein concentrate
  • Sunflower meal, pressed, dehulled
  • Yeast, active dry
  • Yeast, brewers'
  • Yeast, primary dried
  • Yeast, culture
  • Yeast, dried
  • Yeast, torula dried

About the Author

Harold Hintz, PhD, MS

Harold Hintz, PhD, MS, retired from teaching animal nutrition at Cornell University in 2005 and is now a professor emeritus there. He is also a member of The Horse’s Editorial Advisory Board. His main research interest is equine nutrition, particularly mineral and energy metabolism. He has authored 190 peer-reviewed journal articles, 615 articles in non-refereed publications, and has authored or co-authored four books and contributed to 36 books.

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