Effects of varying bulk densities of steam-flaked corn and dietary roughage concentration on in vitro fermentation, performance, carcass quality, and acid-base balance measurements in finishing steers

K. E. Hales, J. P. McMeniman, J. Leibovich, J. T. Vasconcelos, M. J. Quinn, M. L. May, N. Dilorenzo, D. R. Smith, M. L. Galyean

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17 Scopus citations

Abstract

Effects of varying bulk densities of steam-flaked corn (SFC) and level of inclusion of roughage in feedlot diets were evaluated in 3 experiments. In Exp. 1, a total of 128 beef steers were used in a 2 × 2 factorial arrangement to evaluate the effects of bulk density of SFC (335 or 386 g/L) and roughage concentration (6 or 10% ground alfalfa hay, DM basis) on performance and carcass characteristics. No interactions were observed between bulk density and roughage concentration for performance data. From d 0 to the end, cattle fed the 335 g/L SFC had greater overall G:F (P = 0.04) than those fed the 386 g/L SFC, with tendencies (P < 0.10) for improved G:F with the lighter flake weight evident at all 35-d intervals throughout the feeding period. Dry matter intake was less for cattle fed 6 vs. 10% roughage from d 0 to 35 (P = 0.03) and d 0 to 70 (P = 0.05), but not for the overall feeding period. Feeding 6 vs. 10% ground alfalfa as the roughage source tended (P = 0.09) to improve overall G:F. Treatment effects on carcass measurements were generally not significant (P > 0.20). In Exp. 2, the effects of bulk density of SFC (283, 335, or 386 g/L) and 6 or 10% ground alfalfa hay on IVDMD and in vitro pH were evaluated at 6, 12, 18, and 24 h of incubation. With a reduced-strength buffer in vitro fermentation system, pH increased (P < 0.01) with increasing bulk density at 6 and 12 h, and IVDMD decreased (P < 0.03) as bulk density increased. In contrast, in a normal-strength buffer system, there were no treatment differences (P > 0.23) for IVDMD. In Exp. 3, two diets that varied in bulk density of SFC and roughage concentration (335 g/L SFC with 6% alfalfa hay vs. 386 g/L SFC with 10% alfalfa hay) were compared for their effects on the pattern of feed intake and the acid-base balance in Holstein steers (12/treatment). No differences (P > 0.10) between treatments were noted for blood gases or urine pH; however, day effects (P < 0.02) were detected for blood pH, partial pressure of CO2, and urine pH, which generally decreased (P < 0.05) with an increasing time on feed. The 2 treatments had little effect on the pattern of feed intake within the sampling days, with the exception that the 386 g/L SFC with 10% alfalfa hay diet increased (P < 0.05) the percentage of total DMI consumed at 1 and 6 h after feeding on d 14. Within the ranges of bulk density and roughage level studied, 335 g/L SFC with 6% alfalfa hay yielded the optimal animal performance, with limited effects on in vitro fermentation and the acid-base balance.

Original languageEnglish
Pages (from-to)1135-1147
Number of pages13
JournalJournal of animal science
Volume88
Issue number3
DOIs
StatePublished - Mar 2010

Keywords

  • Acid-base balance
  • Bulk density
  • Feedlot cattle
  • In vitro dry matter disappearance
  • Roughage
  • Steam-flaked corn

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