With the ever-increasing availability of soybean and especially corn co-products, owners of beef cows, stockers and feedlots are exploring their options with numerous potentially new feedstuffs. Three products with the greatest availability are corn gluten feed (CGF), distiller's dried grains with solubles (DDGS) and soyhulls.
All three can be excellent feedstuffs for most classes of beef cattle, but as with any product, there are always negatives along with the positives. Let's examine the three products.
CGF & DDGS
Both CGF and DDGS are high in phosphorus (P). While higher levels of P don't cause toxicity problems or reduced performance, it can lead to formation of urinary calculi in feedlot steers. To reduce the risk, feedlot cattle need added calcium (Ca) to raise the Ca:P ratio to 2:1. In beef-cow rations, a Ca:P ratio of between 1 and 2:1 should be adequate.
With any beef animals eating these corn co-products, be sure no additional P is included in the mineral mix, which may necessitate a change in your mineral program. One positive of high P content in corn co-products is that P is one of the most expensive minerals in a typical beef mineral mix. Thus, your mineral mix is generally cheaper when one of these products is fed.
One drawback to high P feeds, however, is that feeding them may necessitate more land for proper manure disposal from a feedlot. P binds to the soil, and concentrations don't decrease as rapidly as nitrates. As P — rather than nitrates — becomes the primary determinant of land needs, this should be considered as an added cost.
Likely the largest concern with feeding CGF and DDGS is that both are high in sulfur. Thus, rations must be balanced with a maximum of 0.3-0.4% total sulfur on a dry matter basis. Cattle can adapt to higher sulfur content, but it's especially troublesome in the early feeding stages.
While polioencephalomalacia (one type of “brainer” disease) may occur with very high sulfur ratios, we can also see issues with feed intake and other nagging disease presentations with prolonged, high sulfur concentrations in feed. As these co-products drop in price, it will be tempting to substitute just a bit more in place of expensive corn, but the risk of cattle getting polioencephalomalacia is just too great.
Remember also that cattle can obtain sulfur from sources other than corn co-products. In fact, most feedstuffs contain some sulfur, with mineral mixes and some hays adding significantly to the total.
Another feedstuff we can't forget as a source of sulfur is drinking water. If you're just beginning to feed corn co-products, or if you have just drilled a new well, testing your water for sulfur should be an absolute. If your water has very high sulfate concentrations (sulfate is ⅓ sulfur), then you may not be able to utilize these products to as large an extent as others.
While soybean hulls don't contain excessively high levels of any mineral, they can produce health concerns. Soyhulls expand a great deal once in contact with moisture in the rumen. If cattle are allowed to consume soyhulls free choice, bloat or excessive rumen distention can occur. Limit soybean hulls in the diet to 1.5% of body weight, at which level bloat should be very unlikely.
Another concern of most byproduct and co-product feeds is variability of nutrient content. While product from a single ethanol plant tends to be quite consistent, product from different plants can vary greatly. Time of year also may greatly affect the nutrient content of CGF, as the amount of steep water added back to the corn gluten may vary with the commercial demand for sweetener.
Always ask for an analysis of any byproduct feed, particularly for minerals such as P and sulfur. In addition, be aware the bio-diesel production process primarily removes the fats from the grain, while ethanol production utilizes the starch. Thus, the resulting byproduct feeds from the two processes have dramatically different characteristics.
Once you have a feed analysis, work with a beef nutritionist, Extension beef specialist or your herd health veterinarian to help you formulate a cost-effective and safe ration for your beef business.
W. Mark Hilton, DVM, is a clinical associate professor of beef production medicine at Purdue University in West Lafayette, IN.