To many people, by-products have a negative connotation. Most think of by-products as “left overs”, “junk” or “fillers”. This is simply not true. Some of the most nutrient rich ingredients we have for horse feeds are made of the product that remains after a grain has been processed for another specific purpose. These ingredients can include things like brewer’s grain, corn gluten feed, oat groats, etc. Some of the most common members of this category that we see used in our horse feeds or even fed as a sole ingredient today are:
Wheat Midds are obtained from the milling of wheat, wheat bran, wheat shorts, wheat germ, wheat flour, etc. Midds are a good source of energy, protein and fiber for horses. Additionally, wheat midds help create a nice pellet that holds together well; midds 
can enhance the pellet quality and make a clean pellet with minimal dust and fines.
Rice bran is a by-product of the rice milling process. Rice bran is found between the outer hull and inner grain of rice and is used as a plant-based fat source (typical rice bran products contain 20% fat or more). Rice bran can be fed in a powder form, extruded into a nugget, or added to commercial rations and pelleted to increase overall fat content of the feed. Rice bran works well as an ingredient but must be balanced to make up for a high phosphorous and low calcium content. It also must be stabilized or it will turn rancid very quickly due to the high oil content.
Wheat Bran is a by-product of the flour industry. It is rich in dietary fiber and essential fatty acids; bran mash has been historically fed to horses both as a treat and for a laxative effect that was thought to prevent colic. We now know that too much wheat bran can cause problems such as enteroliths, and that laxative effect is actually a result of too much wheat bran irritating the gut lining of the horse. Similar to rice bran, wheat bran intakes must be managed to account for a very high phosphorous content.
These are just a few examples of some common grain by-products that are used in horse feed and can help create a healthy and nutritious diet. While not a “grain” by-product, even the ever-popular beet pulp is a by-product – it’s what’s left after sugar beets are processed! Before you dismiss a feed because it lists by-product as an ingredient, remember that these items, when balanced properly as a part of the overall formulation of the diet, can be an excellent source of many different nutrients.
I agree with you that rice bran & wheat bran are good choices but they are not what they mean when they say grain “by product” – actually brans are separated out and sold in health food stores at a big profit. If your label SAYS “bran” then great! But the by products for the most part are the hulls. Some labels are honest enough to list “soy hulls” or “wheat hulls”. The others hide behind “by products”. MEAT “by products” in dog food are really scary!
Hi Gerri,
Thank you for your comments and questions about the term grain by products. The ingredients that are included in that category are primarily co-products, in most cases from human food ingredient production or alcohol production of the grain industry. A great example is wheat midds. This is the portion of the wheat grain that remains after the starch component is removed for human flour use. You are correct that some of the bran does go into human products as well, but the huge amount of wheat that is processed into human flour products (think of all the bread, pasta, pastry etc.) generates more bran than can go into human food supply. Different flour mills split the ingredient stream into different fractions, depending on the type of wheat they are processing and the specific human food products that they are producing.
Hull products, such as soy hulls and almond hulls, are a highly digestible fiber source for horses that cannot be easily digested by humans. In fact, some of the human health food brans are not actually very highly digestible by humans, which is the reason they are being used as health foods to reduce calorie density in human diets.
One of the main reasons the collective term grain by-products is used is to make certain that we can deliver a consistent nutrient flow as ingredients change in nutrient composition without having to change tags every time there is a change in the nutrient composition of an ingredient. If you think of the wheat example, the flour mills have to produce very consistent human grade products from a somewhat inconsistent natural input, wheat. As a result, the co-products that are produced will vary more than the flour. We measure these changes in nutrient composition very carefully so that we can use the different ingredients to deliver a consistent nutrient flow to the animals. Your breakfast cereal has grain products listed in specific terms (and costs around $4-6,000 per ton, based on a 16 ounce box of cereal selling for $2-3+/box). The feed industry takes the grain products that do not go into that box and uses those products to deliver highly nutritious animal feeds, always keeping in mind that animals do not have an ingredient requirement, they have a nutrient requirement. In many cases, we actually have a better understanding of the nutrient requirements of animals than we have of humans. If you look at the progress we have made in the last 20 years on improving the length and quality of life for Senior horses, the focus on nutrients has been good for the animals.
Thank you ~ Roy J.