Influence of corn hybrid, kernel traits, location, and dry rolling or steam flaking on ruminal digestibility in beef cattle

Three trials were conducted to evaluate the effect of corn hybrid, kernel traits, growing location, and dry rolling or steam flaking on DM or starch digestibility or both. Trial 1 used 72 commercially available corn hybrids to evaluate the influence of hybrid on kernel characteristics and their effect on digestibility. Kernel characteristics evaluated were test weight, 1,000-kernel weight, and kernel hardness using the Stenvert hardness test. All analyses were conducted on dry, whole corn samples, and DM digestibility was determined for dry-rolled corn samples. Trial 2 used 12 hybrids to evaluate steam flaking or dry rolling on DM and starch digestibility. Flaking and flaking characterization were conducted at the Department of Grain Science and Industry at Kansas State University. Trial 3 used 132 commercially available corn hybrids grown in 3 separate locations to evaluate the effect of growing location, hybrid, and kernel characteristics on DM digestibility. Hybrids evaluated represented a wide range in relative maturity and, therefore, were separated into similar maturity groups for analysis. Results from trial 1 suggest that softer kernels are more digestible than harder kernels. A 27% difference in DM digestibility was found across hybrids when processed as dry-rolled corn. Results from trial 2 show that steam flaking improved DM digestibility (P < 0.01) from 5 to 29% and starch digestibility (P < 0.01) from 8 to 36% compared with dry rolling. Results from trial 3 suggest that DM digestibility is affected by corn hybrid (P < 0.05) but did not show consistent relationships with kernel characteristics. Our results also suggest that hybrid and growing location may interact, resulting in difficulty separating hybrid differences across locations. Overall, the results of these trials suggest that a softer kernel and a lighter-density flake improve digestibility and that hybrids vary in digestibility.