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Corn DDGS is a high-value feed ingredient in swine diets: Part 1

By Jerry Shurson, University of Minnesota Department of Animal Science
© 2018 Feedstuffs. Reprinted with permission from Vol. 90, No. 05, May 7, 2018


Much has changed over the last 20 years in the choices of feed ingredients available and the way swine diets are formulated. One of the most significant changes is the use of corn-derived dried distillers grains with solubles (DDGS) in diets for all phases of pork production.

In 1998, when the U.S. ethanol industry was in its infancy, about 1.3 million metric tons of DDGS were produced, and only about 52,000 mt (4%) were fed to swine. Today, more than 37 mmt of DDGS are being produced, of which more than 5 mmt (14%) are being fed to swine domestically and another 13 mmt (35%) are being exported for use primarily in swine and poultry diets in Asia and Latin America.

This dramatic increase in DDGS use in swine diets has occurred for three reasons: an abundant supply in major U.S. pork production states, high nutritional and economic value relative to corn and soybean meal and extensive research demonstrating that DDGS can be successfully used at high dietary inclusion rates (up to 30%) in all phases of production to achieve optimal performance.

Energy

Regarding metabolizable energy (ME) and net energy (NE) for swine, corn DDGS and corn contain, on average, similar ME content (3,396 kcal versus 3,395 kcal/kg) and NE content (2,343 kcal versus 2,672 kcal/kg). As a result, DDGS prices are generally highly correlated with corn prices in the feed ingredient market.

However, the energy content varies considerably among sources, with ME content ranging from 2,959 kcal/ kg (Dahlen et al., 2011) to 4,336 kcal/kg (Pedersen et al., 2007) and NE content ranging from 2,012 kcal/kg (Kerr et al., 2015) to 2,915 kcal/kg (Wu et al., 2016a) on a dry matter basis.

One of the reasons for the high variability in energy content among DDGS sources is that the majority (more than 90%) of ethanol plants are extracting some of the corn oil prior to manufacturing DDGS. However, research studies have shown that the oil (crude fat) content of DDGS is a poor single predictor of ME and NE values for swine (Anderson et al., 2012; Kerr et al., 2013).

Therefore, to manage this variability and provide accurate ME and NE estimates of the DDGS source(s) being used, ME prediction equations based on chemical composition measures have been developed and validated (Urriola et al., 2014; Wu et al. 2016b) for use in swine diets.

In fact, some commercial companies use similar prediction equations to provide services to nutritionists and pork producers for comparing relative economic value and customized energy and nutrient loading values for feed formulation of various DDGS sources. These approaches minimize the risk of overestimating and underestimating energy, digestible amino acid levels and phosphorus content in DDGS as part of precision swine feeding programs.


Protein

Although the protein content of DDGS (27%) is more than three times greater than corn (8%), it is much less than for dehulled, solvent-extracted soybean meal (47%). This is one of the reasons why the DDGS price is less influenced by soybean meal prices than by corn prices. More importantly, the lysine content relative to the crude protein content in DDGS (2.97%) is about half the lysine:crude protein in soybean meal (6.20%).

Although the concentrations, balance and digestibility of amino acids in DDGS are inferior to those of soybean meal, DDGS can partially replace soybean meal in swine diets when adequate amounts of crystalline lysine, threonine and tryptophan are supplemented. Unfortunately, crude protein content is a poor predictor of indispensable amino acid content in DDGS (Olukosi and Adebiyi, 2013), and color (Minolta or Hunter L* and b*) is a poor predictor of amino acid digestibility among DDGS sources (Urriola et al., 2013).

However, like for energy, the amino acid content and digestibility vary substantially among DDGS sources (Olukosi and Adebiyi, 2013; Zeng et al., 2017), with the standardized ileal digestibility of lysine (coefficient of variation [CV] = 13.5%), tryptophan (CV = 12.5%), isoleucine (CV = 9.2%) and threonine (CV = 7.1%) being the most variable (Zeng et al., 2017).

Fortunately, prediction equations have been developed to accurately estimate the standardized ileal digestibility amino acid content of DDGS sources for swine (Zeng et al., 2017), which further support precision nutrition swine feeding programs when using DDGS.


Phosphorus

Another unique and economically valuable nutritional component of DDGS is its relatively high standardized total tract digestible (STTD) phosphorus content (0.47%) compared with corn (0.09%), soybean meal (0.34%) and other grain and grain byproduct sources (National Research Council, 2012). Phosphorus is the third most expensive nutritional component in swine diets after energy and amino acids.

As corn is fermented to produce ethanol and DDGS, the phosphorus content is not only concentrated, but much of it is also converted to a more digestible form. As a result, substantial amounts of expensive inorganic phosphate supplements can be partially replaced in swine diets when DDGS is added, which not only reduces diet cost but also reduces the amount of indigestible phosphorus being excreted in manure. However, the STTD phosphorus content also varies among DDGS sources, with digestibility coefficients ranging from 59% (Hanson et al., 2011) to 77% (Rojas et al., 2013).

The addition of phytase has minimal effects on improving phosphorus digestibility in DDGS for swine (Almeida and Stein, 2012; Rojas et al., 2013), and the crude fat content of DDGS has no effect on STTD of phosphorus among DDGS sources (She et al., 2015).

Prediction equations have been developed (Almeida and Stein, 2012) to estimate STTD of phosphorus in DDGS for swine, but unfortunately, they are not sufficiently accurate (R-square = 0.20) for commercial application. Therefore, the conservative estimate (National Research Council, 2012) of 65% STTD of phosphorus in DDGS should be applied to the total phosphorus content of the DDGS sources being used when formulating swine diets.


Economic value

Due to the high ME and NE and digestible phosphorus content and relatively high digestible amino acid content of DDGS compared with corn and soybean meal, the economic value of using DDGS in swine diets can be as much as $60- 100 per ton greater than the purchase price. Numerous studies have shown that adding high amounts of DDGS — up to 30% in phase 2 and 3 nursery, growing/finishing and lactation diets, and up to 50% in gestation diets — maintains performance comparable to feeding conventional corn/soybean meal diets (Stein and Shurson, 2009).

Significant feed cost reductions have been achieved when using these high DDGS inclusion rates to the point where many large pork producers are attempting to find ways to use even greater amounts (50-60%) in grower/finisher diets. However, to achieve optimal growth performance and carcass composition when feeding diets containing more than 30% DDGS, re-examining the threonine requirements and managing excess leucine relative to isoleucine and valine must be considered.

The high fiber content of DDGS may increase the threonine requirement because of increased mucin production in the gastrointestinal tract, which occurs when feeding high-fiber diets to pigs. Mucin contains significant amounts of threonine, which is lost and not used for growth. Corn protein in DDGS also contains high amounts of leucine relative to the pig’s requirement, and excess leucine reduces the utilization of two other branched-chain amino acids: valine and isoleucine. Therefore, feeding diets containing high amounts of DDGS may result in suboptimal growth performance if these conditions are not properly managed in diet formulation.

Research is underway to evaluate ways to overcome these challenges and further increase DDGS use in nursery and growing/finishing pig diets.


References

Almeida, F.N., and H.H. Stein. 2012. Effects of graded levels of microbial phytase on the standardized total tract digestibility of phosphorus in corn and corn coproducts fed to pigs. J. Anim. Sci. 90:1262-1269.

Anderson, P.V., B.J. Kerr, T.E. Weber, C.J. Ziemer and G.C. Shurson. 2012. Determination and prediction of digestible and metabolizable energy from chemical analysis of corn coproducts fed to finishing pigs. J. Anim. Sci. 90:1242-1254.

Dahlen, R.B.A., S.K. Baidoo, G.C. Shur- son, J.E. Anderson, C.R. Dahlen and L.J. Johnston. 2011. Assessment of energy content of low-solubles corn distillers dried grains and effects on growth performance, carcass characteristics and pork fat quality in growing-finishing pigs. J. Anim. Sci. 89:3140-3152.

Hanson, A.R., G. Xu, M. Li, M.H. Whitney and G.C. Shurson. 2011. Impact of dried distillers grains with solubles (DDGS) and diet formulation method on dry matter, calcium and phosphorus retention and excretion in nursery pigs. Anim. Feed Sci. Technol. 172:187-193.

Kerr, B.J., W.A. Dozier III and G.C. Shurson. 2013. Effects of reduced-oil corn distillers dried grains with solubles composition on digestible and metabolizable energy value and prediction in growing pigs. J. Anim. Sci. 91:3231-3243.

Kerr, B.J., N.K. Gabler and G.C. Shurson. 2015. Formulating diets containing corn distillers dried grains with solubles on a net energy basis: Effects on pig performance and energy and nutrient digestibility. Prof. Anim. Scientist 31:497-503.

National Research Council. 2012. Nutrient requirements of swine. 11th rev. ed. Natl. Acad. Press, Washington, D.C.

Olukosi, O.A., and A.O. Adebiyi. 2013. Chemical composition and prediction of amino acid content of maize- and wheat- distillers’ dried grains with solubles. Anim. Feed Sci. Technol. 185:182-189.

Pedersen, C., M.G. Boersma and H.H. Stein. 2007. Digestibility of energy and phosphorus in ten samples of distillers dried grains with solubles fed to growing pigs. J. Anim. Sci. 85:1168-1176.

Rojas, O.J., Y. Liu and H.H. Stein. 2013. Phosphorus digestibility and concentration of digestible and metabolizable energy in corn, corn coproducts and bakery meal fed to growing pigs. J. Anim. Sci. 91:5326-5335. She, U., Y. Su, L. Liu, C. Huang, J. Li, P. Li,

D. Li and X. Piao. 2015. Effects of microbial phytase on coefficient of standardized total tract digestibility of phosphorus in growing pigs fed corn and corn co-products, wheat and wheat co-products and oilseed meals. Anim. Feed Sci. Technol. 208:132-144.

Stein, H.H., and G.C. Shurson. 2009. The use and application of distillers dried grains with solubles in swine diets. J. Anim. Sci. 87:1292-1303.

Urriola, P.E., L.J. Johnston, H.H. Stein and G.C. Shurson. 2013. Prediction of the concentration of standardized ileal digestible amino acids in distillers dried grains with solubles. J. Anim. Sci. 91:4389-4396.

Urriola, P.E., M. Li, B.J. Kerr and G.C. Shurson. 2014. Evaluation of prediction equations to estimate gross, digestible and metabolizable energy content of maize dried distillers grains with solubles (DDGS) for swine based on variable chemical composition. Anim. Feed Sci. Technol. 198:196-202.

Wu, F., L.J. Johnston, P.E. Urriola, A.M. Hilbrands and G.C. Shurson. 2016a. Evaluation of NE predictions and the impact of feeding maize distillers dried grains with solubles (DDGS) with variable NE content on growth performance and carcass characteristics of growing-finishing pigs. Anim. Feed Sci. Technol. 215:105-116.

Wu, F., L.J. Johnston, P.E. Urriola, A.M. Hilbrands and G.C. Shurson. 2016b. Evaluation of ME predictions and the impact of feeding maize distillers dried grains with solubles with variable oil content on growth performance, carcass composition and pork fat quality of growing-finishing pigs. Anim. Feed Sci. Technol. 213:128-141.

Zeng, Z.K., G.C. Shurson and P.E. Urriola. 2017. Prediction of the concentration of standardized ileal digestible amino acids and safety margins among sources of distillers dried grains with solubles for growing pigs: A meta-analysis approach. Anim. Feed Sci. Technol. 231:150-159.

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