Roughage sources in beef cattle finishing diets.

In four feeding trials with beef steers, corn silage (CS), alfalfa hay (AH), and alfalfa silage (AS) were compared as roughage sources in dry-rolled (DRC); dry whole (DWC); ground, high-moisture (GHMC); and whole, high-moisture corn (WHMC) fattening diets. In processed corn diets (DRC and GHMC), steers fed CS had lower DMI (P less than .05) and feed:gain ratios (P less than .10) than steers fed AS as the roughage source. In a separate trial, greater gains (P less than .10) and lower feed:gain ratios (P less than .05) were found during the initial feeding period, which included the adaptation phase, for steers fed CS vs steers fed AH as the roughage source. Over the entire feeding period, lower (corn type x roughage source interaction, P less than .05) feed:gain ratios were found in GHMC diets when CS was fed as the roughage source; feed:gain ratios were similar in steers fed DRC diets containing either CS or AH. Over the entire feeding period, similar performance was found among steers fed the various roughage sources in DWC diets; however, with WHMC diets, steers fed AS as the roughage source had lower feed:gain ratios than did steers fed AH (P less than .05) or CS (P greater than .10). In the processed corn diets, high correlations were found between diet NDF digestibility and gain (r = .80), intake (r = .68), and feed:gain ratios (r = -.66); similar trends were found in WHMC diets but not in DWC diets. These results suggest that the ideal roughage source to complement finishing diets may depend on corn processing method and feeding period (adaptation vs finishing).