USE IN FEEDLOT CATTLE
Interaction of corn processing and co-products feeding

Feeding corn milling co-products in feedlot diets reduces acidosis-related challenges. Both WCGF and WDGS have little to no starch remaining following the milling process. Therefore, feeding these co-products will dilute whatever starch is fed and influence rumen metabolism. Krehbiel et al. (1995) observed a decrease in subacute acidosis when WCGF was fed to metabolism steers. In many studies, feeding WCGF resulted in increased dry matter intake (DMI), which would be a common response to less subacute acidosis.

Because processing corn increases the rate of digestion by microbes, rumen acid production is increased and the risk of acidosis is increased (Stock and Britton, 1993). Feeding WCGF helps prevent the risk of acidosis with high-grain diets (Krehbiel et al., 1995). Numerous studies have been conducted at the University of Nebraska to determine if feeding values are markedly improved in diets containing WCGF when corn is more intensely processed. Scott et al. (2003) evaluated various corn processing techniques and observed improved feed conversions as processing intensity increased when feeding calves or yearlings (Table 8). Ranking of processing based on feed conversions (lowest to highest) was whole corn, DRC, HMC, and steam-flaked corn (SFC) when fed to finishing calves. Relative improvements in F:G for DRC, HMC and SFC compared to whole corn were 6.8, 11.1 and 12.5%, respectively.When fed to yearlings, response to processing was not as favorable as with calves. Feeding HMC did not significantly improve F:G compared to DRC. Macken et al. (2006) fed DRC, SFC, and HMC processed as either rolled (roller mill, RHMC) and ground (tub grinder, GHMC) to calves, with all diets containing 25% WCGF. Whole corn was not fed in this study, but performance was more significantly improved the more intensely the corn was processed. Net energy calculated from performance (NRC, 1996; Owens et al., 2002) was increased by 9.1, 11.0, and 14.9% for RHMC, GHMC, and SFC, respectively, compared to DRC.

HMC appears to have greater feeding value when diets contain WCGF than what was previously observed in diets not containing WCGF. Because HMC has greater ruminal starch digestibility than DRC or SFC (Cooper et al., 2002), cattle fed HMC have a greater potential for acidosis when HMC is fed alone. However, feeding HMC in combination with WCGF appears to increase efficiency of utilization of HMC, perhaps by reducing acidosis. For example, the feeding value of HMC in diets containing HMC as the only grain source is lower than that observed when fed in combination with other grains (Stock et al., 1991) or corn co-products. Previous reviews reported that HMC feeding resulted in 2% greater efficiency than DRC (Owens et al., 1997). However, based on work with HMC-based diets containing 20 to 35% WCGF, cattle are 5 to 10% more efficient than those fed WCGF and DRC. Our conclusion is that intense processing has tremendous value in diets containing WCGF. However, optimal corn processing in diets containing WDGS appears to be somewhat different than diets containing WCGF. Vander Pol et al. (2006) fed diets containing 30% WDGS with either whole, DRC, HMC, a 50:50 blend of HMC and DRC (DM basis), or SFC to finishing steers for 168 days. Cattle fed DRC, HMC, or a combination of HMC and DRC gained more and were more efficient than cattle fed whole corn (Table 9). Interestingly, cattle fed SFC did not gain as efficiently. Corrigan et al. (2007b) investigated feeding DRC, HMC, or SFC in diets containing 0, 15, 27.5 or 40% WDGS.They found greater performance response to WDGS inclusion in diets based on DRC and HMC (Figure 12). Optimal ADG, and F:G were seen with 40% WDGS in DRC based diets, 27.5% WDGS in HMC based diets, and 15% WDGS in SFC based diets. In addition, when diets contained 40% WDGS with DRC the cattle performed just as efficiently as cattle on the SFC diets.A greater performance response to WDGS inclusion in diets based on less intensely processed grain may render them an economically attractive alternative to diets based on more intensely processed grains. It is unclear why steam flaking did not improve performance when diets contained WDGS at inclusion levels similar to WCGF inclusion levels.

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