Corn Gluten Feed for Beef Cattle19 April 2007
By W. Warren Gill, Professor Animal Science and published by University of Tennessee in Beef Cattle Time, Volume 25, Number 2, Spring 2007Corn gluten feed is a byproduct of the wet milling of corn to produce cornstarch, sweeteners, oil and other products. The growth of this industry in recent years has resulted in a relative abundance of a feed which deserves careful evaluation for use in beef rations.
Corn gluten feed (CGF) is typically a combination of corn bran, corn germ and steep liquor. It is available in either wet or dry forms. Dry CGF is available as meal or pellets. It is generally palatable and readily digested by cattle.
While corn gluten feed is derived from corn, the nutrient levels are generally higher than for corn since the ingredients remaining after processing have been concentrated. The crude protein content of CGF is somewhat variable, as would be expected, since the protein content of corn itself is variable. Crude protein values range from 16 to 23 percent, with the lower numbers most common in Tennessee.
The most-used term to describe the energy level in a diet is “TDN,” which stands for total digestible nutrients. The TDN value of CGF is generally around 80 to 83 percent. This is lower than corn (88% TDN), but the form of energy is different. Corn is high in starch while CGF is low in starch. Since starch decreases the activity of the rumen microbes which digest fiber, feedstuffs like CGF, which are moderately high in energy from digestible fiber, are a good “match” for high forage diets.
Corn gluten feed can be an economical source ofnutrients. The protein and energy provided by a hundred pounds of dry CGF (90 percent DM) is roughly equivalent to 75 pounds of corn grain plus 25 pounds of Soybean meal (48 percent CP). The best method to get a fair comparison between CGF and other feeds is to incorporate these in rations formulated on a “least cost” basis. Computer programs are available for this.
Storage facilities also need to be considered. Dry CGF can be stored in grain bins; however, wet feeds require storage in a trench, bunker, bag or wet commodity storage pit. Wet CGF should be used as quickly as possible and stored in a manner that reduces spoilage, especially during the summer. Mold will grow quickly when ambient temperatures reach or exceed 63 degrees F. This will result in about 6 inches of spoiled feed within four to six days. The application of propionic acid at .5 to 1 percent wt./wt. will reduce spoilage for up to 14 days.
Check the mineral content to avoid mineral imbalances due to high levels of phosphorus, potassium and sulfur. Of these, possibly the most serious problem is with sulfur, which routinely reaches 0.5 to 0.6 percent and sometimes higher, particularly in the wet product. This may limit the amount which can be used to about 0.5 percent of body weight (dry matter basis). Sulfur content is a particularly worrisome problem in Tennessee because the Tennessee Forage Mineral Survey has shown that sulfur levels typically run at levels high enough to cause problems with cow-calf and forage-based stocker operations. These problems include rough hair coats, depressed growth rate, compromised immune systems (they get sick more easily) and decreased breeding efficiency.
The high phosphorus but relatively low calcium content could result in a calcium to phosphorus imbalance, particularly if CGF is fed above the recommended level of 0.5 percent of body weight. These limitations have often led producers to blend CGF with other feedstuffs, like corn and soybean hulls.
Several reports of problems with “scorched” CGF pellets have raised some questions. If using pelleted CGF, break open a few pellets and check for discoloration or a “burned” smell. If these are evident, the pelleting pressure may have been too high.