Dried distiller’s grains in steam-flaked corn finishing diets with decreased roughage levels

Distiller's grains are the primary coproduct derived from fuel ethanol production. As the fuel ethanol industry expands into the High Plains, distiller's grains are becoming increasingly available as an alternative feed for livestock. Optimizing the use of distiller's grains in flaked grain rations is important to maintaining a competitive advantage among feedlot producers in this region. Because distiller's grains are relatively high in fiber, it is conceivable that the level of roughages in feedlot diets could be reduced when distiller's grains are fed to cattle. Roughages normally have low energy density; therefore, the cost per unit of energy from roughages usually is relatively high compared with cereal grains or grain coproducts. If the use of distiller's grains would allow roughage levels to be decreased in finishing diets without deleterious consequences for health or performance, this generally would be viewed as a positive attribute. Our objective was to evaluate performance of feedlot cattle fed diets with and without distiller's grains, and assess the effect of reducing the level of added roughage in diets containing distiller's grains.


Introduction
Distiller's grains are the primary coproduct derived from fuel ethanol production.As the fuel ethanol industry expands into the High Plains, distiller's grains are becoming increasingly available as an alternative feed for livestock.Optimizing the use of distiller's grains in flaked grain rations is important to maintaining a competitive advantage among feedlot producers in this region.Because distiller's grains are relatively high in fiber, it is conceivable that the level of roughages in feedlot diets could be reduced when distiller's grains are fed to cattle.Roughages normally have low energy density; therefore, the cost per unit of energy from roughages usually is relatively high compared with cereal grains or grain co-products.If the use of distiller's grains would allow roughage levels to be decreased in finishing diets without deleterious consequences for health or performance, this generally would be viewed as a positive attribute.Our objective was to evaluate performance of feedlot cattle fed diets with and without distiller's grains, and assess the effect of reducing the level of added roughage in diets containing distiller's grains.

Experimental Procedures
Crossbred-yearling heifers (n = 384) were used in a finishing experiment to compare three dietary treatments.Diets all contained steam-flaked corn as the principal energy source.Dietary treatments (dry basis) included a control with 0% dried distiller's grains with solubles (DDGS) and 15% corn silage, and two diets containing 25% DDGSone with 15% corn silage, and the other with only 5% corn silage.Heifers were fed in 24 pens with 15 to 16 cattle per pen and eight pens per treatment.Cattle were transitioned to finishing diets using a series of step-up rations.Final finishing diets were fed twice daily for a period of 85 days.The weight of each pen was measured at the start of the study and again immediately before transporting to a commercial abattoir in Emporia, KS.At harvest, incidence and severity of liver abscesses and hot carcass weight were recorded.After a 24-hour chill, USDA yield grade; USDA quality grade; marbling score; 12th-rib fat thickness; kidney, pelvic and heart fat; ribeye area; and incidence of dark cutting beef were recorded for each animal.

Results and Discussion
Cattle fed the diet containing 25% DDGS with 15% corn silage had feedlot performance equal to that of cattle fed the control diet without DDGS.Carcass attributes were mostly unchanged when distiller's grains were substituted for flaked corn, execpt that cattle fed 25% DDGS produced a greater percentage of yield grade 4 and yield grade 5 carcasses.These results are consistent with observations in previous experiments, in which cattle fed DDGS tended to deposit greater amounts of body fat.Feeding DDGS had no negative effect on quality grade.In fact, the percentage of carcasses that graded USDA Choice or better was numerically greater when cattle were fed diets with DDGS.No other notable effects on carcass characteristics were observed in this study.
Reducing levels of corn silage from 15% to 5% reduced feed intake by approximately 5% in cattle fed DDGS compared with cattle fed the control diet without DDGS.Gains were numerically lower and efficiencies were slightly improved by feeding the lower roughage level, though these differences were not statistically significant.Cattle fed the lowroughage diet maintained carcass attributes similar to those in other treatments.

Implications
When corn silage is used as the roughage source, dried distiller's grains are an effective replacement for steam-flaked corn.When dried distiller's grains are added to finishing diets, it might be feasible to decrease roughage levels with no deleterious effects on cattle performance or carcass quality.

Table 2 . Performance Characteristics for Heifers Fed Steam-flaked Corn-based Finishing Diets with Reduced Corn Silage Levels and 25% Corn Dry Distiller's Grains with solubles (DDGS)
Final live weight was computed by taking hot carcass weight divided by 63.5 dressing percentage. 2 Statistics were performed as gain:feed, reported as feed:gain.ab Means within a row without a common superscript letter differ (P<0.05).

Table 3 . Carcass Characteristics for Heifers Fed Steam-flaked Corn-based Finishing Diets with Reduced Corn Silage Levels and 25% Corn Dry Distiller's Grains with Solubles (DDGS)
Means within a row without a common superscript letter differ (P<0.05).cd Means within a row without a common superscript letter differ (P<0.10). ab