Effects of feedlot bunk management and bulk density of steam-flaked corn on growth performance, carcass characteristics, and liver score of finishing beef steers fed high-concentrate diets without by-products or tylosin phosphate

Abstract

Our objective was to evaluate effects of bunk management strategy and bulk density of steam-flaked corn (SFC) on growth performance, carcass characteristics, and incidence and severity of liver abscesses in finishing beef steers fed diets without tylosin phosphate. Beef steers (n = 192; initial BW = 332 ± 8.1 kg) were used in a randomized complete block design comprised of 12 BW blocks and 12 pen replications per treatment. A 2 × 2 factorial arrangement of treatments was used: (1) slick-bunk management + 335 g/L SFC-based diets (SFC); (2) modified ad libitum bunk management + 335 g/L SFC; (3) slick-bunk management + 425 g/L SFC; (4) modified ad libitum bunk management + 425 g/L SFC. Bunk management strategy did not affect growth performance, carcass characteristics, or liver abscess score (P ≥ 0.10). The ADG of steers fed 425 g/L SFC was greater (P = 0.05) from d 35 to 105 than those fed 335 g/L SFC; however, overall ADG was not different (P = 0.36). The DMI of steers fed 425 g/L SFC was greater at each interim period (P ≤ 0.05) and overall (P ≤ 0.01) than those fed 335 g/L SFC. Gain-to-feed (G:F) of steers fed 425 g/L SFC tended (P = 0.10) to be lesser from d 0 to 35 but was not different overall (P = 0.12). Steers fed 425 g/L SFC tended to have greater backfat and calculated empty body fat percentage (P ≤ 0.07) than those fed 335 g/L SFC and greater calculated YG (P = 0.05). Steers fed 425 g/L SFC had 43.5% fewer (P = 0.04) liver abscesses than those fed 335 g/L SFC, but liver abscess severity did not differ (P ≥ 0.12). Bunk management did not affect growth performance, carcass characteristics, or development of liver abscesses. Steers fed 425 g/L SFC-based diets had greater DMI and 43.5% fewer liver abscesses than those fed 335 g/L SFC-based diets with similar overall G:F, but carcasses were fatter. Greater bulk density of SFC may be a useful management strategy and a viable antimicrobial alternative to decrease liver abscesses.