A byproduct is by definition “a product made during the manufacture of something else.” So when we are referring to byproduct feeds, we are talking about feedstuffs fed to livestock that are secondary products produced after the primary product is made. Typically, these byproduct feeds are of less value than the primary product, and thus the producer of the product is less concerned about their quality.

Sometimes the primary product is used for human use and the byproduct is simply something they must get rid of. However, byproduct feeds can be high-quality and useful, especially in ruminant diets, and they can have a significant economic value over more traditional primary feeds. These feeds can be beneficial in balancing best-cost rations, but some important factors need to be considered.

1. Economics

The main reason to use a byproduct feed in place of a more traditional feedstuff is because of cost. Typically byproduct feeds are less expensive than a given traditional feed and supply some of the same nutrients or physical characteristics. Byproduct feed costs can vary throughout the year and are usually tied to the cost of traditional feeds (i.e., corn, soybean meal, forages, minerals, etc.) and their availability based on when they are produced.

Many computer programs are available that help producers and their nutritionists determine the value of a feedstuff based upon its nutrient value. These programs take into account the market cost of traditional feeds and, based upon the nutrient content of the byproduct feed, calculates an acceptable cost (or range) for any given byproduct feed. In addition, least-cost ration formulation programs can help to determine the value of a given byproduct feed based upon the specific ration being fed.

Be careful not to purchase a byproduct feed just because it is a “good deal.” Cows require specific nutrients and we must supply them with the feeds we use.


Another consideration with byproduct feeds is shrink. Byproduct feeds that are wet or have very small particle size are more prone to higher amounts of shrink. This increased risk for shrink should be considered when calculating costs.

2. Nutrient composition and variation

Because byproducts are secondary feedstuffs of some other process and because raw materials and processing methods can vary, nutrient levels of byproduct feeds can vary significantly. Sometimes byproduct feeds are coming from multiple sources, and variability tends to be higher. Producers and their nutritionists should inquire as to where the byproduct feed is coming from and its typical nutrient content.

Even with this information and even though “book” values exist for most byproduct feeds, they should be tested on a regular basis depending on the feed. Some byproducts are more consistent and a history of sampling will tell you how often you need to sample and analyze.

Work with your nutritionist to determine how often a byproduct feed should be sampled. Take into account not just analyzed values but also try to account for the variation that is typically higher in some byproduct feeds. Some additional analysis may need to be done because of the handling and manufacturing processes of these byproduct feeds (i.e., heat-damaged protein in distillers grains).

3. Limitations on amounts fed

All feeds (including byproduct feeds) have limitations as to how much can/should be fed. For byproduct feeds, suggested limits on amounts fed have been reported and can be found in many publications.

There are several reasons for limiting the amount of a particular byproduct feed in rations, including cost, palatability, moisture content of the feed and the total ration, protein balance, carbohydrate balance, fiber levels and fat concentrations.

Another consideration relates to environmental concerns. Many of these byproduct feeds can be high in phosphorus. Phosphorus is one particular nutrient being monitored and regulated for the land application of manure.

4. Storage

Storage and handling of byproduct feeds must be considered. Some byproduct feeds (wet feeds, bulky feeds, fine particle size feeds) may require special storage and handling. Storage sizes should be sized for the anticipated usage and byproduct feeds should be turned over frequently.

In most cases, byproduct feeds must be purchased in truckload quantities. Calculating usage amounts is important to ensure adequate turnover. Even with enough storage, buying large amounts of a particular byproduct feed at a good price, but not using it quickly enough only to have it spoil or cause excessive shrink, is not a good decision either.

5. Risks and additional tasks

Several risks and additional tasks are associated with using byproduct feeds. Feeds must be sourced, prices must be checked and compared, inventories must be managed and byproduct feeds should be sampled and analyzed on a regular basis.

Quality control can be a major issue with feeding byproduct feeds. Because commercial feed companies are responsible for the quality control of the feeds they make and sell, byproduct feeds don’t typically come with the same assurance. Sometimes sellers of byproduct feeds will actually provide disclaimers stating they are not responsible for the quality of the particular byproduct feed. You may decide not to buy from them again if you do have a problem, but that won’t remedy the situation.

Because they are secondary products that are not as closely monitored as the primary product, byproducts can be more prone to contaminants and quality problems. Aflatoxin can be present in feeds such as cottonseed, cottonseed meal and peanut meal. Other mycotoxins can be present in many feeds including corn byproducts (distillers grains, hominy, corn gluten feed) that can actually be concentrated by the processing. Wet feeds are also more prone to mycotoxins. Feeds that are a byproduct of some human products are likely to be less of a concern.

Byproduct feeds can be a useful and economical alternative to more traditional feeds in dairy diets. Ruminants have an innate ability to digest and utilize many different feedstuffs. However, considerations need to be made as to how the feeds will be fed, their nutrient content and variability, the limitations of how much can be fed, the extra time and risks involved and the quality of the feeds. As with all feed management decisions, work closely with your nutritionist to determine what byproduct feeds should be used in your operation. PD

References omitted due to space but are available upon request by sending an e-mail to editor@progressivedairy.com .

Jim Sullivan