| Abstrakt: |
Three trials were conducted to evaluate finishing diets containing 67% steam-flaked corn (SFC), steamed-whole corn (SWC) or whole corn (WC). In a feeding trial, steers fed SWC consumed more (P<.05) dry matter per day (7.6 kg) than those fed WC (7.0 kg) or SFC (6.7 kg). Average daily gain was greater (P<.05) for steers fed SFC (1.33 kg) and SWC (1.31 kg) than for those fed WC (1.25 kg), and feed efficiency was better (P<.05) for steers fed SFC (5.06 kg dry matter/kg gain) than for those fed WC (5.62) and SWC (5.79). Carcass characteristics were not different among the three groups. In a digestion trial, method of corn processing did not affect digestibility of dry matter and crude protein. Starch digestibility was greater (P<.05) for SFC (99.1%) than for SWC (93.8%) and WC (93.0%). There were no differences in nitrogen (N) intake or fecal N among the three diets; however, urinary N was less (P<.05) for SWC (19 g/d) than for SFC (27 g/d) and WC (32 g/d), and N retention was higher (P<.05) for the SWC diet. In vitro dry matter digestibility of the SFC diet was higher (P<.05) than for WC at 4 and 8 h of incubation and higher (P<.05) than the SWC diet at 8, 12 and 24 h of incubation. In vitro gas production after 6 h was greater (P<.05) for SFC than for SWC grain, which was greater (P<.05) than WC. Particulate passage rate of corn did not differ between SFC (5.1%/h) and SWC (4.9%/h), both of which were greater (P<.05) than WC (2.5%/h). Retention time increased (P<.05) for WC (66.1 h) compared with SWC (46.2 h) and SFC (40.8 h), but was not different between SFC and SWC. Steaming whole corn appears to affect rate of passage of undigested corn residues, which may account for increased dry matter consumption of SWC diets, but feed efficiency was not improved over WC diets. |
