This is an excellent question that is difficult to answer for sure because there is variation from operation to operation depending on distance from ethanol plants, other feed byproducts, size of operation, and price. As price increases in distillers grains, inclusion levels decrease.

There are multiple products available which include: DDGS dry distillers grains plus solubles, WDGS wet distillers grains plus solubles, and WCGF wet corn gluten feed.

You asked about DDG; however, relatively small amounts of DDG are used in Nebraska feedlots for multiple reasons. The majority of the time and almost all the plants in Nebraska produce these byproducts in the wet form (35 to 60% DM; i.e., 65 to 40% water). This is a great thing for Nebraska because wet feeds are less costly for the plants (they don't have to spend the money or energy to dry the feed from the wet form to make DDGS), and the wet feeds are actually a better feed for feedlot cattle. Feeding in the wet form creates some challenges, but these can be overcome.

There are two main approaches to using these byproducts. One method is to feed enough to just meet the protein needs of the cattle. The inclusion levels in this situation are usually 10 to 15% of the diet DM or less than 3 lb of DM per steer each day. If feedlots use the DDGS, then it is almost always used as a protein supplement only. However, this could change in the future if more is available at a lower price. We are currently conducting studies with DDGS because they may be a better fit for smaller operations and we are also studying its use in forage situations. The price is usually higher for DDGS because when it is dried, then it is usually marketed as a protein supplement and priced relative to soybean meal. This is commonly used by dairies as a protein supplement, but there are some research available on swine and poultry use at low concentrations in the diet.

The second method or approach to use of ethanol byproducts is to replace energy or corn. Inclusion levels as an energy replacement are usually 10 to 40% of the diet for WDGS. WCGF could also be used this way and it is common to see levels of 10 to 40% of this byproduct. In terms of lb, this would be feeding 4 to 8 lb per day of DM. Our data on use as an energy source are provided in a report available under "byproducts" on the http://beef.unl.edu website. This approach works well.

To answer your questions, average inclusion levels (my best guess today) is approximately 10% DDGS (if using at all, but perhaps 10% or less of the cattle), 15 to 25% inclusion for WDGS, and 20 to 30% inclusion for WCGF.

You ask an excellent question about concern dealing with this extra phosphorus. Because corn contains approximately 0.3% phosphorus, the feed byproducts contain between 0.8 and 1.0% P depending on how it is made, how much solubles are put back on, or whether you are talking about WCGF. In some situations (only DDG or WDG without solubles), you may see feeds as low as 0.4 to 0.5% P. Feedlots are being regulated to monitor how nutrients are spread in manure relative to amounts of N and P that are spread on land acres. In some situations, we have applied more P than the crop needs, which can create challenges with runoff from fields. This is not a challenge in the feedlot where runoff is already controlled, it is more of a challenge when manure is spread.

From a state-wide perspective, Nebraska is in a very good position. We export 40% of our corn, which means 40% of the P in corn leaves Nebraska. Our challenge is in local areas. As a feedlot industry, we have had this challenge before byproducts were available, and now with feeding more and more byproducts, this challenge is certainly greater. We have been working on this to determine what does it cost the producer to spread manure further. For example, if it cost the feedlot more to spread manure when byproducts are used compared to the advantage of using byproducts in terms of cattle profitability, then feedlots should not use them. Our data suggests it is still quite economical ($15 to 25 return per head finished) to use byproducts compared to increased cost of spreading manure further ($1 to 3 per finished animal). However, this assumes you can go further to the next field. So, we have challenges in local areas and cattlemen are quite concerned about how to manage this, but we are working on it. There is also some research projects underway at UNL to remove P from byproducts to decrease the level that would be fed when they are used as a feed.

Source: Extension.org