Abstracts Health Sciences

Performance and carcass characteristics of finishing beef steers fed high-oil corn or normal corn plus added fat

by Hart Michael Derington

One hundred twenty Angus steers with an initial body weight (BW) of 288 kg were fed for 165 d to evaluate the effects of a steam-flaked high-oil corn-based diet (HOC) vs a steam-flaked normal corn plus added fat-based (CON) diet. The two diets were balanced to be isocaloric and isonitrogenous. Steers were assigned randomly by weight to one of the two treatments and housed five per pen, with 12 pens per treatment. Steers were fed once daily and weighed every 28 d throughout the study. Performance records including average daily gain (ADG), dry matter intake (DMI), and feed:gain ratio were recorded for each 28-d period. Following the 165-d feeding period, the steers were shipped to a commercial slaughter facility where carcass data were collected and recorded. Initial BW did not differ between treatments, whereas final BW tended (P < .08) to be greater for steers fed the CON diet. Steers fed CON had increased ADG during d 0 to 28 (P< .03), d 0 to 84 (P < .02), and for the overall 165-d feeding period (P < .04). Daily DMI did not differ (P > . 10) between treatments for any of the cumulative periods; however, steers fed HOC averaged approximately .23 kg/d more DMI for the entire 165-d feeding period. Feed:gain ratio was superior for steers fed CON for each of the cumulative periods (P < .01 to P < .03). Moreover, for the 165-d feeding period feed:gain ratio was improved 7.5% (P < .01) for steers fed CON. Hot carcass weight, dressing percent, fat thickness, kidney, pelvic, and heart fat (KPH), and yield grade did not differ between treatments. Steers fed HOC tended (P < .07) to have a smaller longissimus muscle area as well as a lower (7.4% decrease; P < .01) marbling score than steers fed CON. Percentage of carcasses grading USDA Choice did not differ between treatments. These data contradict previous experiments with HOC, which showed improvements in performance and carcass characteristics with HOC diets; however, previous experiments involved shorter feeding periods than in the present study.