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Beautiful But Misunderstood: The story of byproducts and their value

I've been sitting on this topic for a while, but with the recent increase in feed prices, I thought now would be an appropriate time to sing the praises of these poorly understood horse feed ingredients! I anticipate a lot of people looking for alternatives to their pricey feed bags this year. This article breaks down the advantages and disadvantages of several types of by-products, so that you can be more informed. Besides the everyday by-products you all have in your feed room right now, we'll also explore hemp products, spent brewer's grains, lignin sulfonate, and grass screening pellets.


The word "By-Product" is terrifying, right? It conjures up images of cesspools, green "Teenage Mutant Ninja Turtles" slime and dangerous warning signs, but without by-products we would not have the horse feed industry that we know today. For our equestrian purposes, it's important to realize that we're narrowing the definition to mostly GRAIN by-products. Grain by-products include the complex fibers, protein-rich meals, or high-energy oils extracted from seeds such as corn, wheat, barley oats, rice, soybeans, and canola. Each seed type has its own unique profile of nutritional properties including fiber, non-structural carbohydrates, protein and fat that come from one of three structures in the seed; outer hull, middle bran, or inner endosperm/germ. If you study the wheat and rice diagrams below, you'll notice that all seeds have a protective outer shell (aka hull), several middle layers known as the bran, and two inner layers known as the endosperm and the germ (aka embryo). Grain by-products are co-produced in the extraction of one or more of these layers to create bread, sugar, beer, oil and other modern products we use everyday. To combat the negative cultural connotation, I prefer to use the word "Co-Products". These co-products are immensely valuable to horse diets, and I'd like to show you why!

Common Byproducts of Manufacturing Stuff for Humans that Ends Up in Horse Feeds

- Fiber Rich Co-Products: beet pulp, wheat middlings, soybean hulls, dried distillers grain solubles (DDGS) Excellent summary article about DDGS LINK HERE.

- High Fat Co-Products: rice bran, soybean, canola, camalina, and flaxseed oils

- Protein Rich Co-Products: soybean meal, canola meal, alfalfa meal


The ingredients above have served the equine feed and supplement industries well due to their a) consistency, b) safety, c) affordability, d) availability. e) palatability, and f) nutritional value. I can not overstate the importance of these factors. You would be loath to buy a bag of feed that your horse didn't like, that was nutritionally variable, unsafe, or double the cost of what you're paying now to feed skinny, old, growing or high performance horses. Without co-products we would not have senior feeds, growth formulas, most performance feeds, and we would certainly not have high fat-low carb horse feeds. One of the greatest values of co-products is the safety and efficacy of the calories contained within the leftover seed parts. Horses are very, very good at extracting energy from these fiber rich sources like beet pulp, rice bran and wheat middlings. These ingredients have replaced more sugar/starch rich whole grains such as corn, oats, and barley which have historically been used to keep farm and warhorses fit.

A VERY cool fact about most co-products is their low non-structural carbohydrate value (%)- see the Co-Products Comparison Chart below. The common thread of low NSC is due to the extraction of most sugar and starch for our own use in foods, oils, ethanol and so much more. Beet pulp is a great example of that. US Farmers grow sugar beets to then extract the sucrose (a natural plant form of sugar) from the rootball. The fiber that is left over from that sugar extraction is beet pulp. It starts out in the shredded form and then can be ground further and pressed into a pellet for homogeneity, low dust, and ease of use. Beet pulp was one of the first co-products of manufacturing to be used extensively in horse feeds back when we had no forage alternatives for old horses, horses with poor teeth, and skinny, picky eaters! Beet pulp must have seemed like a miracle food at the time when all we had was C.O.B. and is still used in most senior, performance and growth feed formulas today.

The term "by-products" often gets confused with the term "fillers". To learn more about "fillers", please read "Lions, Tigers, and Fillers...OH MY!" from OCEN, LLC.

Even more frightening, without common co-products, feed prices would be even higher. A client texted me yesterday to inform me that the senior feed I had recommended cost $38 per 50 pounds. I was shocked. Just a few weeks ago, this bag was probably closer to $30. It secured my fears that recent inflation would have a big impact on the equine feed industry. Prices at the feed store are very sensitive to fuel and ingredient prices due to very tight margins. Thank goodness for co-products in these horse feeds! If you look at the Digestible Energy column of the Co-Products Comparison Chart below, you'll see the relatively high calorie values. The presence of these co-product ingredients lowers the cost per calorie of horse feeds. Rice bran is a good example of this. If you purchase a 50# bag of rice bran from the feed store for $20, you're buying about 75 Megacalories. That means you're paying about $0.27 per Megacalorie- that's great! For comparison, a 50# bag of beet pulp at $18/bag will cost you $0.30 per Megacalorie, and an affordable, fully fortified performance feed will cost you $0.33 per Megacalorie.


Every single ingredient that you could ever feed your horse comes with its own inherent strengths and weaknesses that include a) consistency, b) safety, c) affordability, d) availability. e) palatability, and f) nutritional value (yes, this is the same list as above in advantages section). A good nutritionist will weigh these pro's and con's when formulating a product or diet plan. One disadvantage of co-products is their nutritional and visual variability. Because ingredients may arrive at a feed mill from all over the world, the batch color, smell, texture and nutritional guarantees will range. A good feed mill, with the help of a good nutritionist, will balance this variability with other ingredients and fortification when creating any performance, senior, growth or low carb feed. A disadvantage of buying co-products alone is that nutritional value will fluctuate more than we'd like. A good example of that is the fat content in rice bran which actually varies quite a bit between 15-25%. Color and texture may vary as well especially if you are purchasing soybean meal, canola meal, or dried distillers grain solubles in a bag or from a local farmer.

Another disadvantage of co-products is their relatively high phosphorus and low calcium values which must be corrected for in the rest of the diet. This inverted calcium to phosphorus ratio is naturally occurring in most seeds. It's not a huge threat to your horse's health if you're feeding small amounts of these ingredients, but you will want to counterbalance this ratio when feeding large amounts- especially for the young, growing horses and the old, geriatric horses.

The last caution to co-products that I'd like to mention is safety. All plants, from the potted plants in your home, the grasses in your lawn, and the hay you throw over the fence, comes with its own compliment of microorganisms and their by-products! I absolutely do not say this to scare you (it's part of being a plant), but the microorganism by-products I mention are also known as mycotoxins. Sometimes mycotoxins are concentrated in co-products, so it's something to be knowledgable about. It is hard to know which ingredients are the safest is horse feeds without regular testing, so the best line of defense is to buy from reputable sources that test, test, test! That means asking more questions from your local brewery, hemp manufacturer, or farmer before adding unregulated, untested co-products to your horse's diet.


Example #1

Hemp By-Products: A friend in Montana was approached about representing a local hemp manufacturer's by-products including a protein rich treat and a hemp seed oil marketed to horse owners. They also have a hemp hull product to complete the three major categories of by-products that come from seeds (to review they are complex fibers, protein-rich meals, and high calorie oils). I think what they are doing here is cute, and many people will likely be attracted to the novelty of hemp snacks, but let's be real here... giving your horse a few hemp cookies a day isn't going to make a meaningful difference in your horse's nutrition. As you all know by now, I get SUPER annoyed when supplement companies have a long list of claims that a couple handfuls or scoops of their product is going to be THE THING. Seriously...their marketing company went ALL out! Take a look at the claims made on their hemp seed oil! Because hemp seed oil is high calorie just like every single other oil on the face of the planet, it could be a great addition to any skinny horse's diet. Yet, when we look at $80 per gallon compared to the $25 per gallon of other oils, that overall value quickly diminishes. The omega-6 to omega-3 ration is 3.25 to 1, so we can't really call it a super valuable omega-3 source either. Read "The Perfect Oil for Horses- Fat Chance!" for clarity on this topic.

Hemp Protein Snacks (a.k.a. Seed Cake) (CP 31%, Fat 12%, ADF 41%, NDF 52, DE 1.33 Mcal/lb)

Hemp Hulls (CP 12%, ADF 61%, NDF 77%, DE 1.03 Mcal/lb)

Hemp Seed Oil: Link to IND Hemp Oilseeds and Fiber is HERE. (52% Omega-6 and 16% Omega-3).

*For a better comparison of oils and their omega-3 to 6 content, read "The Perfect Oil for Horses- Fat Chance" by OCEN, LLC.

Example #2

Spent Brewer's Grains: A friend recently asked me about adding the waste product of her local brewery to her horses' diets. Predictably, there are advantages and disadvantages that must be considered. As you can see from the Co-Products Comparison Chart, spent brewers grains have lovely protein and fiber values- 25.6 % crude protein and 50.7% crude fiber. The great variability of spent brewer's grains could be managed very carefully, but you would also need to consider the following...


- Must be close to the source to make transportation feasible.

- Need special equipment to transport it and an appropriate place to store it.

- Nutrient consistency which may cause variability in performance.

- Mycotoxins and molds from wet product.

For these reasons, I do not recommend it for performance horses. I have not seen it work long term for any horse farms.


Great protein and fiber sources for livestock close to the source where freshness is possible. Breweries and local farms can create a symbiotic relationship with spent brewer's grains.

Example #3

Lignin Sulfonate: The Feed Room Chemist did an excellent podcast recently about the co-product lignin sulfonate and its use in horse feeds. Dr. Nichols debunks an emerging myth that lignin sulfonate is dangerous to horses in any way. It's a co-product of pulping trees to make paper and a million other things and is useful to us. Take a listen by clicking the link above.

Example #4

Grass Seed Screenings: I was recently asked about the use of grass seed screening pellet as a forage alternative for horses. I saw this product often when I lived in the Willamette Valley for a spell. The Willamette Valley in Oregon is known as the "Grass Seed Capitol of The World" producing a significant percentage of all ryegrass, bentgrass, fescue, orchardgrass and even Kentucky Bluegrass seeds to be packaged and delivered around the country for lawns, turf, golf courses, and more. Grass seed screenings are the leftover from the cleaning of these seeds between field and packaging. I do not recommend them. The presence of mycotoxins is far too risky for regular use in horse feed diets. Notice how the purpose statement is limited to cattle and sheep? This is not an accident. Cattle and sheep can withstand the negative side effects of mycotoxins better than horses can. Stay away from grass seed screening pellets for horses.


What I want every equestrian to take away from this discussion of by-products or co-products, is that they play an integral role in creating valuable horse feed products. Every grain seed that has ever been utilized for human consumption has a set of co-products that include complex fibers, protein-rich meals, and high energy oils and often they can hold greater value than the whole seed by itself (i.e. low carb values). Whether or not they are appropriate for use in your horse's diet will depend on how you value a) consistency, b) safety, c) affordability, d) availability. e) palatability, and f) nutritional value (yes, this is the same list again). Like all equine nutrition, it's important to keep an open mind about these ingredients, but also think critically about how they fit into your horse's nutrition goals.

If you have a question about a by-product ingredient or would like to learn how to feed your horse better, then you can schedule a FREE 15 Minute Discovery Call with OCEN's nutritionist by clicking HERE.


Brewing by-products: Their use as animal feed. 2002. PubMed. Accessed on March 21, 2022 from,diets%20of%20ruminants%20and%20horses.

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