Corn Processing Co-products Manual
A REVIEW OF CURRENT RESEARCH ON DISTILLERS GRAINS AND CORN GLUTEN

A joint project of the Nebraska Corn Board and the University of Nebraska Lincoln Institute of Agriculture and Natural Resources Agricultural Research Division Cooperative Extension Division
Brought to you by Nebraska corn producers through their corn checkoff dollars expanding demand for Nebraska corn and value-added corn products.

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FEEDING DISTILLERS GRAINS TO DAIRY CATTLE

P.J. Kononoff and Brandy Janicek
Department of Animal Science
University of Nebraska-Lincoln
INTRODUCTION

The production of ethanol from corn grain has become an effective strategy to produce high quality and clean liquid transportation fuels. In fact, the growth of the U.S ethanol industry has provided an economic stimulus for U.S.-based agriculture.The feed industry plays an integral role in the ethanol production industry. For example, the primary product of the dry milling production process is ethanol; but approximately one-third of the total dry matter is recovered in the form of co-products. The supply of these co-products continues to grow at a rapid rate. As a result co-products are becoming an increasingly available feedstuff that are usually an extremely cost effective feed ingredient for lactating dairy cattle.

In the dry milling process, either corn or sorghum is cleaned, ground dry and the whole kernel is used in the fermentation process to produce ethanol and carbon dioxide. In this case there are basically two products of interest.The first product is the solid, unfermented grain portion called wet distillers grains (WDG) and second is the thin stillage fraction that contains water, small particles, yeast and all other soluble nutrients. If not sold as WDG, material may be further dried yielding dried distillers grains (DDG); and in some cases the thin stillage is added back to yield dried distillers plus solubles (DDGS). Table 1 lists the estimated nutrient content of corn distillers grains (CDG) and other common feeds.

NUTRIENT COMPOSITION OF DISTILLERS GRAINS

PROTEIN
Protein contained in the feed can be utilized by rumen microbes. However, the rumen undegradable protein (RUP) portion may by-pass the rumen and supply the small intestine with protein where it is digested and absorbed. On a dry matter basis, corn distillers grains contain approximately 30% crude protein, commonly ranging between 25 and 35%. Corn distillers grains are a good source of rumen undegradable protein (approximately 50%), with wet being slightly higher than dry.

Our growing understanding of protein nutrition and utilization has lead us to consider the use and supply of individual amino acids (AA) during ration balancing procedures. Limiting AA are defined as those amino acids that are in shortest supply (Socha et al., 2005).The NRC (2001) suggests methionine (MET) is most limiting in rations that depend upon soy or animal protein for major RUP supply. In rations that are formulated to contain high amounts of corn products, the supply of lysine (LYS) is believed to be more limiting (Liu, et al., 2000). In diets containing 20 % CDG, the supplementation of ruminally protected lysine and methionine results in an increase in milk protein percent and yield (Nickols et al., 1998), but this has not been observed in all studies (Liu et al., 2000).When balancing diets containing high levels of CDG, nutritionists should evaluate the proportion of predicted lysine and methinone in the metabolizable protein (MP) fraction. More specifically, nutritionists should strive for a lysine to methionine ratio (LYS:MET) of 3.0:1.0. Although in most situations, this bench-mark may be difficult to reach, nutritionists may improve the amino acid profile of the ration by increasing the inclusion rate of high-LYS protein supplements such as fish meal or soy-products.

ENERGY AND EFFECTIVE FIBER
Although field nutritionists often view CDG as a useful protein or nitrogen source, this feedstuff contains more than simply nitrogen. Feeding distillers grains in replacement of corn grain is useful in providing energy in the form of fermentable fiber. Because fiber is digested at a slower rate than other forms of energy such as starch, feeding CDG to ruminants may be useful in reducing the incidence of rumen acidosis (Klopfenstein et al., 2001). Distillers grains typically contain 34% neutral detergent fiber (NDF) and 13% fat on dry matter basis. Energy requirements for maintenance and milk production are expressed in net energy for lactation (NEL) units.The current NRC (2001) publication outlining the nutrient requirements for dairy cattle calculates an NEL value on the total diet. Even though the energetic contribution of individual feeds is a function of other feeds included in the diet, there is interest in knowing the baseline NEL value of individual feeds because most formulation programs require NEL as a nutrient input.The energy content of CDG, when replacing corn and soy bean meal, has recently been evaluated (Birkelo et al., 2004).This research suggests that the NEL value for wet CDG is 1.03 Mcal/lb and is 10-15% higher than the current NRC listing. This and other research supports the suggestion that CDG is an excellent ruminant feed and that the digestible fiber portion of this feedstuff is a valuable source of energy. Nutritionists should be reminded that the NEL -value of CDG may be variable and depend on several factors including the chemical composition and the digestibility of the feed itself (most notably NDF and fat), the level of intake and the nature of other ingredients fed to the animal.

Effective fiber is the portion of the diet that is believed to stimulate rumination, chewing activity and saliva secretion, all which is designed to help to maintain healthy rumen function and normal pH levels. Nutritionists are often concerned about rumen pH because when pH levels fall below 6.0, fiber digestion may be impeded and milk fat levels may become depressed (Russell and Wilson, 1996). It is believed that rumen pH is a function of lactic acid and VFA production and is buffered by saliva (Maekawa et al., 2002). Because of this finding, it is a common practice to feed diets of longer particle size, therefore a greater amount of effective fiber, so that saliva production is stimulated. In support of this hypothesis, Krause et al. (2002) noted that the intake of particles > 19.0-mm was negatively correlated with the amount of time rumen pH was below 5.8. However, it is also known that diets should not be excessively long or coarse as they are more difficult to mix and may induce cattle to sort out ration ingredients (Kononoff et al., 2003).When CDG are used to substitute forage in the TMR, chewing activity is believed to be reduced due to the finer particle size. Nutritionists should not necessarily use this logic to infer that feeding CDG will result in lower rumen pH. In fact it is likely that diets may be balanced so that the inclusion of CDG will not influence rumen pH.When evaluating a diet to determine a possible risk of subclinical acidosis, it is important to also consider levels of fiber and non-structural carbohydrates, along with their associated fermentability (Yang et al., 2001). Using the Penn State Particle Separator, at least 5-10% of the particles should be at least three quarters of an inch long and the diet should contain 26-30% NDF.

PHOSPHORUS AND SULFUR
The mineral content of feeds and the associated levels in livestock manure has received considerable attention. When including CDG into dairy diets producers should understand that although they contain many valuable nutrients, these feeds may also contain high levels of both phosphorus and sulfur. Although it is unlikely that these levels would contribute to the loss of any milk production or health problems, producers should be mindful of the importance of dealing with these minerals. Recently, the land application of dairy manure has risen to national attention and continues to face growing scrutiny because manure may accumulate minerals and has the potential to contaminate surface and groundwater.To avoid these problems, producers should ensure that their waste management plan attempts to avoid excessive accumulation of minerals and allows for maximum crop use of the nutrients contained in the manure.

WET VERSUS DRY ... PRACTICAL CONSIDERATIONS

As mentioned above, distillers grains may be available in either a wet or dry form and the nutrient content, when expressed on a dry matter basis, is similar for both. One possible major difference between CDG of these forms may be the fact that the RUP portion may be higher for CDG in the dry form (Firkins et al., 1984). Although it is generally believed that there is little difference in milk production when animals are fed either form, beef feedlot studies have demonstrated that rations containing wet distillers grains are consumed in lower amounts and result in greater feed efficiencies than those containing dried distillers grains (Ham et al., 1994). Unfortunately less research has investigated possible differences in milk performances. In one study in which lactating dairy cattle were fed diets containing 15% (DM basis) of either wet or dry CDG no differences were observed in milk production, composition, fiber digestibility, and efficiency of milk production (Al-Suwaiegh et al., 2002).

When deciding which form may fit best, producers should evaluate several factors including distance from plant of origin, the anticipated feeding rate, the on-farm storage facilities and handling equipment. Because a wet product may not be stored as long and is usually associated with high shipping charges, dried forms may be most feasible if a plant is not located near the farm. However, this also increases the price of the feedstuff. If the farm is located near a plant, wet forms may be cost effective, but producers should be mindful of the fact that the rate of spoiling is also dependent upon the feeding rate and environmental temperature. Generally speaking, wet loads should arrive at least weekly to ensure the pile is "fresh." There continues to be interest in ensiling feeds such as wet distillers grains as a method to eliminate oxygen exposure and ultimately reduce feed spoiling and loss. Additionally, a number of commercial direct application preservative products may be useful in extending shelf life of these feeds, but producers should be mindful of these added costs.

CONSIDERATIONS FOR FEEDING

NUTRIENT VARIATION
Recent investigations conducted at the University of Minnesota (Knott et al., 2004) has demonstrated that there may be a high degree of variation in the nutrient content of co-products, such as distillers grains, both within and across production plants. For example, these investigators demonstrated that the crude protein level in distillers grains may range from 25 - 35%, with variation also observed in fat (10-12%), NDF (8-10) and phosphorus (0.8-1%).These investigators note that one of the greatest sources of nutrient variation for DDGS depends on the amount of solubles that were added to the grains. Along with the concentration of CP, the availability of these nutrients may also vary. Hence researchers are beginning to direct their attention towards creating practical methods for controlling this variation. Research from The Ohio State University (Weiss, 2004) suggests that routine feed sampling is essential. Because it may be difficult and time consuming to sample and formulate rations based on lab results of individual loads, numerous load samples should be collected and analyzed over time.This will allow for estimation of the mean values and also the variation of these estimates. Consequently, it becomes possible to protect against underfeeding a nutrient such as protein by feeding an anticipated mean value of the feed.

FEEDING LEVELS AND PRODUCTION RESPONSES

It is impossible to recommend an optimal inclusion level of CDG, as it depends upon many factors including price and the nutrient content of all available feedstuffs.A number of investigators have evaluated the effects of increasing levels of distillers grains in replacing both forages and concentrates (Powers et al., 1995; Owen and Larson, 1991; Garcia et al., 2004; Kalscheur et al., 2004; Leonardi et al., 2005). Conservative estimates from these studies suggest that 15-20% of the ration DM may be included in a properly formulated ration for a lactating cow. Research also suggests that the addition of CDG to dairy diets usually results in an increase in DMI (Nichols et al., 1998; Powers et al., 1995; Owens and Larson, 1991); however this is not observed in all cases (Leonardi et al., 2005 and Schingoethe et al., 1999). Nevertheless, the increase in DMI is not surprising given that intake is influenced by feed particle size and digestive passage rate (Beauchemin et al., 2005) both of which have been demonstrated to increase in diets containing milling coproducts (Boddugari et al. 2001).

In published studies evaluating CDG as a protein supplement, milk production was observed to either be unaffected (Clark and Armmentano, 1993; Owen and Larson, 1991) or increased (Powers et al., 1995; Nichols et al., 1998). Because CDG may contain as much as 13% ether extract (an estimate of crude fat), the high level of fat is one factor believed that may affect milk fat synthesis and as a result limit the inclusion of CDG into dairy diets. This effect was not observed by Leonardi et al. (2005) who evaluated the effects of increasing levels (up to 15%) of CDG and the addition of corn oil to the control diet. These investigators observed an increase in milk and protein yield, thus demonstrating that CDG is a good energy source for dairy cows when the overall diet contained approximately 28% NDF and 5% fatty acids.

Practically, when CDG is introduced into the ration, the inclusion should proceed at a logical and measured pace. Producers should first discuss potential availability of these feedstuffs with their nutritionists. As mentioned, generally speaking the closer the farm is to a plant, the lower the cost will be. Proper evaluation of any ration change should allow the cows to consume the diets for at least three weeks so that cows and their rumen microbes can adapt to the change. Milling products are very palatable and after adaptation, dairy cattle may even increase dry matter intake. If intakes appear to increase, be sure that enough feed is mixed up each day to allow for approximately 5-10% refusal. Final evaluation of the change should include observations of intake, milk production and composition and ultimately consideration of income over feed costs.

SUMMARY AND CONCLUSIONS

Feed co-products from the dry-milling industry are quickly becoming common and cost effective ingredients in dairy diets. Current research suggests that it is possible to include CDG at 20% of the diet DM.When including CDG into dairy diets, nutritionists should ensure that the diet contains adequate levels of lysine, NDF, and effective fiber and they should be mindful of the high concentration of fat in this feedstuff. Future research should be directed towards understanding how diets may be formulated to contain greater than 20% of the diet DM without affecting milk production and composition.

REFERENCES

Al-Suwaiegh, S., K. C. Fanning, R. J. Grant, C.T. Milton, and T. J. Klopfenstein. 2002. Utilization of distillers grains from the fermentation of sorghum or corn in diets for finishing beef and lactating dairy cattle. J. Anim. Sci. 80:1105-1111.

Beauchemin, K.A. and W. Z.Yang, 2005. Effects of physically effective fiber on intake, chewing activity, and ruminal acidosis for dairy cows fed diets based on corn silage. J. Dairy Sci. 88: 2117-2129.

Boddugari, K. R.J. Grant, R. Stock, and M. Lewis. 2001. Maximal replacement of forage and concentrate with a new wet corn milling product for lactating dairy cows. J. Dairy Sci. 84: 873-884.

Brikelo, C.P., M.J. Brouk, and D.J. Schingoethe. 2004.The energy content of wet corn distillers grains for lactating dairy cows. J. Dairy Sci. 87: 1815-1819.

Clark, P.W., and L. E. Armentano. 1993. Effectiveness of neutral detergent fiber in whole cottonseed and dried distillers grains compared with alfalfa haylage. J. Dairy Sci. 76:2644-2650.

Firkins, J. L., L. L. Berger, and G. C. Fahey, Jr. 1985. Evaluation of wet and dry distillers grains and wet and dry corn gluten feeds for ruminants. J. Anim. Sci. 60:847-860.

Garcia, A.D., K.F. Kalscheur, A.R. Hippen, and D.J. Schingoethe. 2004. Replacment of alfalfa haylage with ensiled wet distillers grains and beet pulp in lactating dairy cow diets. J.Dairy Sci. 87 (Suppl 1): 465.

Ham, G.A., R. A. Stock,T. J. Klopfenstein, E. M. Larson, D. H. Shain, and R. P. Huffman. 1994.Wet corn distillers co-products compared with dried corn distillers grains with solubles as a source of protein and energy for ruminants. J. Anim Sci. 1994 72: 3246-3257.

Holt, S.M. and R.H. Pritchard. Composition and nutritive value of corn co-products from dry milling ethanol plants. Unpublished.

Kalscheur, K.L., A.L. Justin, A.L. Hippen, and D.J. Schingoethe. 2004. Increasing wet distillers grains in the diets of dairy cows on milk production and nutrient utilization. J. Dairy Sci. 87 (Supp. 1): 465-466.

Klopfenstein,T. J. 2001. Distillers grains for beef cattle. Pages 1 9 in Proc. National Corn Growers Association Ethanol Co- Products Workshop "DDGS: Issues to Opportunities," Nov. 7, 2001, Lincoln, NE.

Knott, J. and J. Shurson, and J. Goil. 2004. Effects of the nutrient variability of distillers solubles and grains within ethanol plants and the amount of distillers solubles blended with distillers grains on fat, protein, phosphorus content of DDGS. http://www.ddgs.umn.edu/research-quality.html. Accessed November 1, 2004.

Kononoff, P.J., A.J. Heinrichs, and H.A. Lehman. 2003.The effect of corn silage particle size on eating behavior, chewing activities, rumen fermentation in lactating dairy cows. J. Dairy Sci. 86: 3343 3353.Krause, K.M., D.K. Combs, and K.A. Beauchemin. 2002. Effects of forage particle size and grain ferment ability in midlactation cows. II. Ruminal pH and chewing activity. J. Dairy Sci. 85: 1947 - 1957.

Liu, C., D. J. Schingoethe, and G. A. Stegeman. 2000. Corn Distillers Grains versus a Blend of Protein Supplements with or without Ruminally Protected Amino Acids for Lactating Cows. J. Dairy Sci. 2000 83: 2075-2084.

Maekawa, M., K.A. Beauchemin, and D.A. Christensen. 2002. Effect of concentrate level and feeding management on chewing activities, saliva production, and ruminal pH of lactating dairy cows. J. Dairy Sci. 85: 1165 - 1175.

National Research Council (NRC). 2001. Nutrient Requirements of Dairy Cattle. 7th Revised Edition. Natl. Acad. Sci. (Washington DC).

Nichols, J. R., D. J. Schingoethe, H.A. Maiga, M. J. Brouk, and M. S. Piepenbrink. 1998. Evaluation of corn distillers grains and ruminally protected lysine and methionine for lactating dairy cows. J. Dairy Sci. 81:482 491.

Owen, F. G., and L. L. Larson. 1991. Corn distillers dried grains versus soybean meal in lactation diets. J. Dairy Sci. 74:972-979.

Powers,W. J., H. H.Van Horn, B. Harris, Jr., and C. J Wilcox. 1995. Effects of variable sources of distillers dried grains plus solubles or milk yield and composition. J. Dairy Sci. 78:388-396.

Russell, J.B. and D.B.Wilson. 1996.Why are ruminal cellulolytic bacteria unable to digest cellulose at low pH? J. Dairy Sci. 79: 1503-1509.

Schingoethe, D.J., M.J. Brouk, and C.P. Birkelo. 1999. Milk production and composition from cows fed wet corn distillers grains. J. Dairy Sci. 82: 574-580.

Socha, M.T., D. E. Putnam, B. D. Garthwaite, N. L.Whitehouse, N. A. Kierstead, C. G. Schwab, G.A. Ducharme, and J. C. Robert. 2005. Improving Intestinal Amino Acid Supply of Pre- and Postpartum Dairy Cows with Rumen-Protected Methionine and Lysine. J. Dairy Sci. 2005 88: 1113-1126.

Weiss,W.P. 2004. Randomness Rules: Living with variation in the nutrient composition of concentrate feeds. Proceedings of the Mid-South Ruminant Nutrition Conference, Arlington,TX. Pages 39-46.





For more information on feeding distillers grains to dairy cattle, contact: Dr. Paul Kononoff • University of Nebraska-Lincoln • Animal Science Department Room C220J • Lincoln, NE 68583-0908 • 402-472-6442

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Date published: January, 2005

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