USE IN FEEDLOT CATTLE
Interaction of roughage and co-products feeding

Roughages are often included at low levels (<12% of diet DM) to control acidosis and maintain intake in feedlot cattle (Stock and Britton, 1993). Since coproducts reduce the occurrence of acidosis in feedlot cattle, then perhaps roughage levels may be reduced from conventional levels in diets containing co-products. Farran et al. (2004) fed either 0 or 35% WCGF with either 0, 3.75, or 7.5% alfalfa hay at each level (i.e. treatments were factorialized with WCGF level and hay level). There was a significant interaction between WCGF and alfalfa level for feed conversion; therefore, only simple effects are presented in Table 10.With 0% WCGF, increasing alfalfa level increased ADG and DMI with no effect on feed conversion.With 35% WCGF, increasing alfalfa hay increased ADG and DMI, but hindered (increased) feed conversion linearly. It appears that roughage can be decreased in DRC-based diets that contain 35% or more WCGF. The ADG was reduced for the 0% hay, 35% WCGF treatment, so a small amount of roughage is recommended even when WCGF is included. Similar results have been observed with SFCbased diets where alfalfa can be reduced to 2% with at least 25% WCGF (Sindt et al., 2001). Parsons et al. (2001) observed no change in feed conversion when roughage was decreased from 9 to 0% alfalfa in SFC diets with 40% Sweet Bran WCGF. However, in their study, DMI and ADG decreased linearly. Just as with data in conventional corn-based diets, optimum amount of roughage appears to be dependent on grain processing and level of WCGF.

Benton et al. (2007) fed alfalfa hay, corn silage, or corn stalks as the roughage source in 30% WDGS (DM basis) diets. Each of the sources was included at a conventional level and one-half that level (Table 11).The normal level was equal to 8% alfalfa hay and the low level was equal to 4% alfalfa hay. In general, normal roughage levels increased DMI,ADG, and profit. However, steers fed 3% corn stalks performed similarly to steers fed normal levels of roughage. When roughage was eliminated from the 30% WDGS diets, DMI, ADG, and profit were decreased compared with diets containing cornstalks or normal levels of alfalfa or corn silage.Therefore it is not beneficial to completely eliminate roughage sources from finishing diets containing 30% WDGS (DM basis).

Wet co-products allow the use of lower quality roughages because they contain considerable protein and because the moisture minimizes sorting of all ingredients, especially the lower quality roughages.The lower quality roughages have higher fiber contents so diets should be formulated on the basis of their fiber content. Small amounts of roughage, equal to 3 to 4% alfalfa hay, should be included in diets with wet co-products to ensure good levels of DMI and ADG.

For more information or to request additional copies of this manual, contact the Nebraska Corn Board at 1-800-632-6761 or e-mail k.brunkhorst@necorn.state.ne.us.

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For more information on the feeding of corn milling co-products to beef cattle
and information contained in this manual, contact:
Dr. Galen Erickson, University of Nebraska-Lincoln, Department of Animal Science Room C220, Lincoln, NE 68583-0908, 402-472-6402

Date published: August, 2007